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Ecology Notes - ALL
Ecology (The University of Western Ontario)
Studocu is not sponsored or endorsed by any college or university
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Ecology Notes
Chapter 1
- Ecology: The study of interactions between organisms and their environment that
determine the distribution and abundance of organisms
• Ecology is a rigorous science, ecologists study
organisms and how they interact with each other
and with the environment, and ecologists study
how these interactions lead to the patterns of
distribution and abundance for each species
- Ecology is not the same as environmental science
- Environmental science is an interdisciplinary
science that includes ecology but also includes
sustainability, economics, etc and is focused on
finding solutions to environmental problems
- Ecology sits at the intersection of other sciences
- Organism: An individual animal, plant or single celled life source
- Population: All inhabitants of a particular place
- Community: A group of people living in the same place or having the same thing in
common
- Ecosystem: A biological community of interacting organisms and their physical
environment
- Biosphere: The regions of the surface and atmosphere of earth or another planet
occupying living things
- Landscape: An area that included patches of multiple ecosystems
- Biotic: Living components of a natural system
- Abiotic: The physical or chemical components of the environment (precipitation,
temp, pH, mineral nutrients, sand) not living
- Adaptation: A characteristic that improves an organisms ability to survive or
reproduce
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- Natural Selection: The process by which individuals
with particular characteristics tend to survive and
reproduce
- If the characteristic under selection is heritable the
offspring may have the same characteristic and the
frequency of that characteristic increases over time
- Example is antibiotic resistance
- Ecosystem Processes: Energy Flow
- Producers (=autotrophs or primary producers):
Produce their own food from an external source of
energy
- Consumers: Obtain food/energy by eating other
organisms
- One way flow of energy from the sun
- Snakes and owls gain energy by
eating lower level consumers
- Red arrow shows loss of energy in the
form of heat, waste product and
decomposition
- Ecosystem Processes: Nutrient Cycle
- Nutrients are recycled within the
ecosystem
- Some of the carbon in our bodies
could have been in a dinosaur 100
million years ago
- 1. Organisms and their
environment are interconnected
(ecological maxims (principals))
- There are eight maxims of ecology
- Even small changes in the
environment can effect one or
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more of the local organisms which can affect all other organisms
- seasonal changes in temperature (black line) and precipitation (blue bars) for a
hypothetical ecosystem
- Some organisms will not be able to thrive when the temperature drops below the
freezing point and may need to migrate or hibernate, this takes away a food source
for its consumer
- Anyone action can affect all others
- 2. Everything goes somewhere
- Waste materials do not disappear when they go down the drain or into the garbage
- The first law of thermodynamics (law of conservation of energy) applies to
everything
- Our waste effects the ecosystem
- 3. No population can increase in
size forever
- Eventually they are limited y
predators, resources or space
- Some cycle between high and low
- 4. Finite energy and resources lead to trade-offs
- Increased allocation of
energy to one function,
leads to a decreased
allocation to another
function
- Common trade off is
growth versus
reproduction
- Plant grows small with lots
of fruit or big with little fruit
- More nutrients needed for
big plant with lots of fruit
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- 5. Organisms evolve
- Evolution never stops: selection pressures never end
- (1) Two mice species interbred in Germany. One, the house mouse, is susceptible
to warfarin (a common rodent pesticide). The other is the wild Algerian mouse,
which is closely related to the house mouse. Most hybrid offspring are infertile.
However, some of these hybrids survived, thrived in the city and have immunity to
warfarin
- 2) In Florida, native green lizards were forced up to smaller branches in trees by an
invasive brown lizard. After 15 yrs (about 20 generations), the green lizards
evolved due to selection for changes that enable them to cling to slender branches
at the treetops
- 6. Communities and ecosystems change over time
- Ecosystems are not static, change is normal
- With global warming the accelerated rate of change is a problem but even before
that ecosystems were in flux
- After a fire or flood a new forest might be exactly like the old one or might be new
- 7. Organisms are affected at varying spatial scales
- The sea star, for example, is affected by its immediate environment, its neighbours,
changing conditions within its tidal pool and in the ocean bay…all the way up to
global factors
- 8. Organisms require
interactions
- You have already
seen that species
depend on each other
for energy and
nutrients. Many
species also depend
on others for habitat.
For example, the red
squirrel in this image
may nest in a pine tree.
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- Events in the natural world are interconnected
- Some of the connections are not immediately obvious
- A problem seen at one level (for example, amphibian decline) can be caused by a
multitude of factors, including abiotic and biotic factors
- Within 2 ponds, 14-45% of tadpoles/frogs had deformities
- The scientists discovered that the 4 ponds
with deformed frogs were also the only ponds
that had aquatic snails that carried a parasite
- Back in the lab they determined that the
parasites could cause limb deformities
- The scientists exposed tadpoles to one of four
parasite treatments (1, 16, 32 or 48 parasites
per tadpole; x-axis) then watched to see how
many of the developing frogs would have
deformed limbs
- The greater number of parasites the greater
percentage of frogs with deformities
- The scientists returned to six of the ponds; three were close to agricultural fields
and the water contained pesticides; three
other ponds had no detectable pesticides
- The frogs were placed in cages with differentsized mesh
- In the left column, the data indicate that no
deformities developed in the absence of
parasites. However, in the right column, the
data indicate that parasites are not the only
factor. In the absence of pesticides (top right
cell) only 4% of the frogs has deformities
- The pesticides apparently weakened the
frog’s immune system, making it more
susceptible to parasitic infection
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- Testing Ecological Hypotheses:
- a) Observational experiments
- Ecologists typically use one of three types of
experiments to test their hypotheses
- The first category of experimental design is
observational
- Do not involve experimental manipulation
(experimental treatments)
- Replication is an essential component
- The observations that (1) not all ponds had
deformed frogs, (2) ponds with deformed frogs
also had a parasite and (3) the proportion of
deformed frogs in an ‘infected’ pond varied, led to
the hypothesis that deformity is caused by a parasite.
- b) Controlled experiments
- Conditions are controlled such that
the hypothesis can be tested directly
- The experimental design for the lab
experiment that generated these
data included four experimental
treatments (along the x-axis), one of
which is the experimental control (0
parasites). Specifically, this is a
negative control because one would
not expect any deformities in frogs
given this experimental treatment
- If frogs in the control (0 parasite)
group developed deformities, the
hypothesis would not be supported
- If the percentage of frogs with deformities did not increase with the addition of
parasites, the hypothesis would not be supported
- Controlled experiments are not restricted to the laboratory
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- This field experiment was designed to
test the hypothesis that deformities were
caused by both parasites and pesticides
- Two sets of experimental treatments
were used: ponds with and without
pesticides, and cages that did or did not
allow parasites to enter
- Because there were two experimental
variables, there needed to be two
controls (no pesticide and no parasites).
There were three replicates for each type
of treatment
- Observational and controlled
experiments can be designed at a broad
range of scales
- Ability to replicate
experimental treatments is
easier in smaller scales (test
tubes vs a field)
- c) Modelling Experiments
- In this type of experiment,
scientists will start with a preexisting dataset, then they
design and apply a computer
model to predict (project)
alternative outcomes given
different experimental
conditions
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Chapter 2 & 3
- Climate is a fundamental component of the physical environment
- Weather: May vary from day to day
- Included humidity, precipitation, temp, wind, clouds
- Influences what you will wear
- Climate: Is based on long term patterns of temperature, precipitation and wind
- Seasonal trends
- Decades of averages of temp and precipitation
- Influences where we vacation or retire
A) Air currents
i) Temperature
- Daily and seasonal variation in climate are controlled by solar radiation
- Our planet is heated by the sun
- ½ of the solar energy hitting Earth is
absorbed by Earth’s surface and the solar
intensity is highest at the equator
- Seasonality arises from the axis of earths
rotation around the sun
- During the spring and fall equinox, the sun
crosses the plane of the equator, making
day and night about equal in length
across the globe. During the solstice,
the sun is at its highest (summer) or
lowest (winter) at noon.
ii) winds
- High pressure = cold air descending
- Low pressure = warm air rising
- Black arrows show average wind
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pattern in july
- Variables such as cloud cover and shifts in zones of high and low pressure will cause
daily (or weekly) changes in weather
- You are, however, expected to understand the concepts behind the patterns
iii) Precipitation
- Combination of surface wind patterns and atmospheric pressure
- Uplift: warm air rises
- Subsidence: Cool air falls
- Intense solar radiation at the equator forms Hadley cells, atmospheric currents on
either side of the equator
- The air movement starts with uplift. When the warm air reaches the upper edge of the
troposphere, it flows towards a pole
- Troposphere is 20km thick
- As the air cools it depends towards
earth (subsidence)
- Together, uplift and subsidence
generate cells of circulating air
- The polar cells are driven by
subsidence of cold air at the poles.
Ferrell cells are driven by the
movement of polar and Hadley cells,
and by the exchange of energy
between air masses
- Note how the patterns of precipitation
and air pressure correlate with zones
of uplift and subsidence
B) Ocean Currents
i) Upwelling
- Water in the ocean can move horizontally and vertically
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- If the prevailing winds blow parallel to a coast (as is common on the western coasts
of N and S America) the force of wind and the Coriolis effect of Earth’s rotation cause
surface waters to flow away from the coast (see left-side image)
- Deeper, colder water moves up from the bottom of the ocean to replace the displaced
waters
- This phenomenon, called upwelling, is essential for coastal marine life because
these currents bring nutrients from
decomposed material on the ocean
floor back up into the zone where
aquatic plants and other organisms live
- A gradient of water temperature that is
independent of air temperature forms
around zones of upwelling. You can
see (right-side image) a point of
upwelling off the coast of California,
where the cool deep waters have been
brought up to the ocean surface
ii) Global Pattern (the great
ocean conveyor belt)
- Ocean currents are responsible
for about 40% of the heat
exchange between the tropics and
the polar regions, which is why
they are sometimes called heat
pumps or conveyor belts
- Most of earth water is in the ocean,
a driving force for weather and
climate
- The earths surface is warm unevenly by the sun
- The ocean absolves and stores more heat than the atmosphere
- Moves heat slowly
- Winds drive currents in the ocean
- Multiple factors keep the ocean conveyor belt in motion
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- Below the surface deeper currents are driven by differences in density
- Nutrient rich waters go from bottom to top
- Replacement of cold water to warm water results in air temp swings and changes in
humidity
- Alters weather patterns by steering stops and rainfall to new locations \shifts in rain
fall affect plant growth
- Green and dry seasons
- When heat is exchanged between the ocean and the atmosphere it influences
climate
- Heat and moisture carried by the gulf stream north bring warmer temperatures and a
moderate climate to Europe
- Eddy is a circular movement of water off the main current and exchange heat and
nutrients
- Winds can make thunder storms turn into hurricanes
- Heat makes rapid storm intensification
- Extracting large amounts of heat from the ocean causes hurricanes to grow
- The ocean is a driving source for weather and climate
- Without the ocean our planet would be dead
- Ocean currents determine, weather, climate
- Ocean currents transport heat from equator to poles
- Ocean conveyor belt is important for our climate
- Exchange of water between our oceans
- Circulation system
- Also called Thermohaline Circulation (halin is salt content)
- Determine density of water
- Evaporation causes an increase in salinity and starts the gulf stream
- Different densities of oceans are responsible for movement
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- Warm water has a low density and rises while cold water is opposite
- Density increases with higher salt content
- At the equator the heat of the sun is strong causing a lot of evaporation
- Thats where the gulf stream starts (important for European climate)
- Many species use the gulf stream
- Warm air comes with the gulf stream (heat pump)
- Pacific garbage path
- Largest of 5 hot spots
- Polar regions have the greatest daily fluctuations in day length and seasonal
fluctuations in temperature
- In equatorial regions, the sun’s rays strike Earth’s surface at a more perpendicular
angle than they do toward the poles. This means that the same amount of energy is
spread over a(n) smaller area in equatorial regions than in polar regions
- Compared with land at the same latitude, ocean waters tend to be warmer in the
winter and colder in the summer because water has a higher heat capacity than land
has.
- Atmospheric and oceanic circulation patterns establish global patterns of
temperature and precipitation
- a) Global annual temperature
- Solar radiation
- Ocean currents
- Elevation
- Land vs water heat capacity
- This pattern of yearly average temperature arises
primarily from the tilt of the earth’s axis and resulting
solar radiation
- Polar regions experience winters without much sunlight.
Equatorial regions receive direct sunlight year round
- Also influenced by ocean currents (white arrow shows gulf stream)
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- Elevation also affects temp (high
mountains are cooler)
- b) Annual seasonal variation in
temperature
- The global pattern is heavily
influenced by the difference in
heat capacity between water and
land
- Water heats up slower than lands
and retains heat longer
- c) Global annual precipitation
- The global patterns of average precipitation are driven by atmospheric currents
(Hadley, Ferrel and Polar cells) Recall the difference between high pressure
(cooler, denser, holds less water) vs low pressure (warmer, holds more water) cells.
- Latitude will determine whether the precipitation falls mostly as rain or snow
- Africa would have precipitation patterns closest to what would be predicted based
on the positions of the Hadley circulation cells
- Regional Climates Are Influenced By…
- a) Mountains
- Temperature decreases as altitude increases
- As air moves up it cools
- Cooler air holds less water, water vapour
condos
- Causes clouds with rain or snow
- Windward slopes are moist, depending slopes
are dry because air is heating
- The leeward slopes of mountains have an
arid climate, this phenomenon is called a ‘rain
shadow’
- b) Oceans and other very large bodies of water
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- Oceans provide moisture to the air
- Clouds build up during the day due too higher air humidity
- Large water bodies and oceans also have less seasonal variation in temperature
due to the high heat capacity of water
- c) Vegetation
- Vegetation will cool the regional air mass
- Albedo is the amount of solar radiation that a surface reflects
- The colour of the
surface will affect
its albedo, with
lighter colours
reflecting more
heat energy
- The rough surface
of vegetation will
lose less sensible
heat due to more
turbulence and reduced wind
- Latent heat loss is the energy lost through evaporation and transpiration
(collectively called evapotranspiration). While water may evaporate more readily
from bare soil, transpiration of water from vegetation will dissipate considerable
heat
- Deforestation in the tropics should result in a(n) increase in the land’s ability to
reflect solar energy (Albedo) and decreased latent heat transfer
- Snow is white, and thus has a higher albedo than bare ground. If global warming
decreases snow cover, the resulting change in albedo is likely to enhance further
warming.
- Terrestrial Biomes Are Defined by Vegetation Type
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- Biome: A large scale biological community
that is shaped by its physical environment
- Seasonal variations in annul precipitation
and temperature patterns determine global
distributions of biomes
- Deserts and dry but not just warm
- Growth Form: Size and morphology (not
taxonomy
- Each growth form has a characteristic
leaf/needle type and typical climate
and environment
- Convergence: Evolution of a similar
train among distantly related species in
response to similar selection pressure
- Convergent evolution
- Bottom pic of plants
- Thick stem small leaves
- The biome distribution closes matches the precipitation and heat distribution
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- First one is potential second is actual biome distribution
- Agriculture and urbanization adds to human footprint and changes biomes
- When people build cities it displaces natural vegetation
- Rainforest: Plants fighting for light
- Different trees and vegetation block the light from completely reaching the bottom
of the forest
- Due to layering
- Emerging trees then canopy trees then
epiphytes(grow on branches of trees to
get light) then lianas (thick vines to get
more light) then the understory (very
large leaves to get more light) get light
- Biological zones on mountains:
- Mimic the biomes we might find as wego from tropics to polar region
- Latitude matches altitude
- In general, biomes in the temperate zone have been changed the most by human
activity
- Freshwater Biological Zones Vary With Water
Characteristics
- A) Lotic Ecosystems (stream orders)
- Lotic ecosystems are within flowing water such as
streams and rivers
- Classified bases on a system of stream ‘order’
- First order arise from glacier or snow melt, natural
springs and rainfall
- When two first order stems meet, they merge into a second order
- Two second order streams merge into a third and so on
- Abiotic factors in lotic environments:
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- Current velocity
- Substarte type
- Water temp
- Clarity (ligt)
- Chemistry (pH, O2,
salinity, nutrients)
- Streams have riffles (fast moving water over course particles), and pools (slow
moving water deeper, cooler and over a bed of fine sediment)
- Distance between riffles can be long or short
- Spatial zones of a stream:
- Lotic ecosystems have 4 zones
- Bottom is the hyporheic zone
- Interaction between groundwater and stream water, which is also called
surface water
- Water moves in and out of this zone
- Feels solid to touch
- Inhabited by certain microbes and some insects
- The benthic zone is what
you would consider to be
the bottom of the stream
- The surface on which you
could stand on
- Inhabited by many
species of invertebrates
(e.g., crustaceans, fly
larvae) and some algae
- The main channel is the body of water where you would find swimmers &
floaters (e.g., fish and algae)
- Plankton are not strong enough to swim against the water current
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- The riparian zone is the area around the stream that is periodically flooded,
especially during the spring thaw or during a heavy rainstorm
- b) Lentic Ecosystems
- Abiotic factors in lentic environments:
- Depth
- Water temp
- Clarity (light)
- Chemistry (pH, O2, salinity, nutrients)
- Within still water such as lakes and ponds
- Substrate type in streams is replaces with water depth
- Depth affects both light and water temp (deeper = less light that reaches the
bottom and the water is colder
- Spatial zones of a lake:
- 4 zones
- The benthic zone, just as in a lotic system, is the bottom of the lake where some
invertebrates and algae live
- The open water is called the pelagic zone,
which is where you would find plankton
and nekton
- The photic zone is a subset of the
pelagic zone, it is delineated by the depth
to which light can penetrate
- The littoral zone is where macrophytes
grow and is delineated by the shoreline
down to the lower edge of photic zone (i.e., photosynthesis can occur in the
littoral zone)
- Marine Biological Zones Vary With Light, Water Depth, and Substrate Type
- The spatial zones of the marine environment are very similar to those of lakes
- One difference is that the littoral zone is replaced by the nearshore zone
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- As in lakes, photosynthetic organisms
such as algae can thrive only in the
photic zone
- Nearshore (tidal) biological zones vary
with temperature and substrate type
- Tidal zone is under influence of the
tides
- Vary with temp and substrate type
- Dont memorize these
- Shallow ocean (sub-tidal) biological zones vary with depth and temperature
- The sub-tidal (shallow ocean) zone is
shallow enough for rooted plants but
remains submerged during low tide
- Coral reefs founds in warm shallow
ocean with lots of light
- Kelp beds in clear shallow temperate
oceans with many species of brown
algae
- Seagrass is not actually grass;
seagrass beds contain over 60
species of underwater flowering plants that can live with relative low light but
require warm temperatures
- Open Ocean
- Some of the marine animals seem not be limited by temperature in the open
ocean– they inhabit it all
- Zooplankton feed on phytoplankton as well as smaller zooplankton, Oceanic
nekton include whale, octopus and sea turtles
- The distribution of larger nekton species seems to be limited only by the availability
of food (zooplankton, phytoplankton, small fish)
- Migrate to more food
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- If something happens at any one spot on Earth it is sure to affect most, if not all,
large ocean animals
Chapter 4
1. Each species has a range of
environmental tolerances that
determines its potential geographical
distribution
- Tolerance: Polar bears tolerate arctic
conditions year round
- Organisms is adapted
- Avoidance: Arctic terns migrate to avoid
arctic winters
- Avoids harsh conditions
- Brown is summer
- Blue is fall
- A species potential geographic is
constrained by…
- a) The Physical Environment
- Availability of resources and energy
- b) Its Physiological Tolerance Limits
- Each species has its own limits for each factor
(temp, salinity, pH)
- … And Extreme Environmental Conditions
- Climate Envelope: Range of climate conditions
under which a species occurs
- Predicted distribution (precipitation, temp, etc)
- Dark green is predicted
- Black is actual (extreme unfrequent events like a
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frost killings flowers on the trees so no reproduction)(southern can be a drought)
- Distribution and abundance vary across environmental gradients
- Actual distribution is always smaller than
potential for every species
- A species actual geographical distribution is
constrained by
- a) Disturbance
- Frost or drought
- Forest fires, volcanoes, wind storms, climate
change
- b) Biological factors
- Red and purple pic
- Barnacle larva are free swimming,
might not be strong enough to get
too far (ability to disperse)
- Competition between 2 barnacle
species (red and blue). Red is
superior
- Individuals respond to environmental
variation through acclimatization
(acclimation for plants)
- New label on y axis
- Happens whens theres a change
in a variable (temp) for a period
of time
- Results in shift of tolerance curve
(i.e. if global warming increases
temp we get a shift
- For example 12 degrees in September is colder than 12 degrees in February
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- Acclimation differs from
adaptation because adaptation is
a genetic change, acclimation is
a short term physiological
change that is reversible
- Ecotypes: Locally-adapted
population within a species
- White stripe vs no white stripe
- Ecotypes have adaptations (i.e. fro camp)
- White stripe feeds on left plant solid green feeds
on right plant
- Ecotypes may eventually become new species
- Left jack rabbit is from the arctic because its
bigger and warmer
- Shorter limbs to protect from frost bite
- Acclimation and adaptation require investment of
energy and resources
- Increases survival and reproductive under the
specific environmental conditions… but possible
trade offs with other functions
- i.e. trade off of eyes on louder laying flat, both
eyes on one side
2. The temperature of an organisms is determined by exchanges of energy with
the external environment
- Survival depends on internal temperature
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- Most mammals have a narrow range of internal temps
- In humans internal body temperature typically ranges from 36.5 to 37.5 °C
- Hyperthermia when over 41 and
hypothermia under 35
- Many invertebrates and plants, can
tolerate much broader ranges of internal
temperatures
- Internal body temperature affect enzyme
activity and membrane function which
affect all physiological processes
- Graph shows enzyme activity to temp
- Most enzymes are active between 20-40 °C
- At the other extreme, arctic fish have some enzymes that are active at temperatures
as low as -5 °C
a) General stargazes for reducing temperature
- Reduce solar radiation by moving into the shade, increase convection by allowing
more wind to carry away heat energy, increase conduction by moving into a cooler
area (my basement is a great place to hang out on a hot summer day!), and utilize
the latent heat of vaporization by sweating or by placing a dampened cloth on the
body dog
- When the water evaporates, heat energy is used and the body cools
- Organisms can increase their body temperature by increasing solar radiation, or by
decreasing convection and conduction
b) Energy balance by plants
i)
Alter solar radiation
- Aquatic plants don’t usually need
to reduce their leaf temperature
because water absorbs and
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dissipates much of the solar heat energy
- Terrestrial plants can absorb heat energy and become warmer than the air temp
- Sunned leaved have less surface area the shaded leaves which will reduce the
absorption of solar heat energy
- Dense white hairs (pubescence) increase albedo (reflection of light energy) and help
to keep the leaf cool but causes less photosynthesis
- Plants have evolved many adaptations to maximize or minimize the absorption of
solar radiation
- Big leaves for forest floor
- Smaller leaves to absorb less sun
- Cactus spines (modified leaves) while stem
takes over photosynthesis to protect the stem
and increase albedo
- The skunk cabbage can (1) generate its own
heat through increased metabolism and (2)
decrease albedo by having purple flowers
- Enough heat to melt the snow around it and
attract pollinators
ii) Alter convention by changing the boundary layer
- Boundary layer is a thin layer of undisturbed
air that surround all objects, animate and
inanimate
- Convection of heat (curved blue arrows) from
an object can be reduced by increasing the
depth of the boundary layer
- Wearing a hat in winter increases the thickness of our boundary layer around our
head, reducing heat loss
- Smooth leaf = thinner boundary layer = more
energy lost by convection
- Hairy leaf = thicker boundary layer = less
energy lost by convection
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- Hairs on the leaf surface will increase the depth of the boundary layer. The longer and
denser the hairs, the thicker will be the boundary layer, and the more heat will be
retained by the leaf
- Divided leaves have thinner boundary layers
- The image on the left shows the area to perimeter ratio (black line) for an undivided
leaf with the same overall dimension of a divided leaf
- Air can flow between the lobes decreasing the boundary layer thickness and
increasing convective heat loss
- Some plants also have ‘windows’ which decrease the boundary
iii) Utilize latent heat of vaporization (via transpiration)
- Gas exchange in plants is done through stomata on the leaves
- Water inside the plant is mostly
liquid
- Inside the leaf, water is vaporized
(enters the gas phase) and exits
via the stomata
- When water vapour exits a
stomate, the process is called
transpiration
- Plants can dissipate heat energy
by transpiring and utilizing the latent heat of vaporization
- When the stomata are closed transpiration stops and the leaves are about 22 to 24
degrees when the stomata are open transpiration resumes and the plant is cooler
c) Energy balance by animals
- Animals can be divided into two categories based on regulation of their body
temperature
- Endotherms rely on internal metabolic
generation of heat. All birds and
mammals as well as a few insects, fish
and plants are endotherms
- Ectotherms regulate their body
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temperature by exchanging energy with the environment. The majority of animal
species are ectotherms (fish and reptiles, insects and amphibians)
i)
Alter solar radiation
- Mobile animals can adjust their behaviour to help regulate body temperate
- Move in and out of the shade to cool and heat
- If it gets too cold animals migrate, hibernate or burrow
- Endotherms cannot tolerate freezing; a few ectotherms can freeze
- Most ectotherms that can freeze are invertebrates (i.e. frog that freezes)
ii) Alter convection and conduction
- Seasonal shedding
- Many mammals have thicker fur coats during winter and shed the excess fur in the
spring
- Change the thickness of the boundary layer and affects convective heat loss
- When humans are cold, the hairs on their arms and legs rises slightly; this small
increase in boundary layer thickness will slightly reduce convection of heat from the
skin
- Behaviour can also affect heat loss
- Tucking in limbs to further reduce convective heat loss
- Spreading limbs to increase convective heat loss or swimming to increase heat
conduction
iii) Utilize latent heat of vaporization (via perspiration/panting)
- The evaporation of sweat or saliva from animals releases heat energy due to the
latent heat of vaporization
- Birds release heat by performing a gular flutter, which involves passing air rapidly in
and out of the mouth without inflating the lungs
- Sweating is restricted to mammals but not all can sweat all over their bodies
- Cats can sweat only through their paws
- How elephants keep cool:
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- Through skin
- Skin is too big for its body
- Heat energy is lost through the skin the the more skin the better
- Wrinkles give it greater area for heat to escape
- Cool down in muddy water
- Mud in fold hold moisture in the skin when they leave the pool and gradually
evaporates to cool the elephant
- Ears radiate a lot of heat
- When its hot blood vessels open and allow blood to cool in paper thin skin in ears
- Flap the ears
- All the blood in an elephant can be pumped through the ears in 20 mins
- How penguins stay warm
- Stick together in huddles when its windy and take turns standing in the middle
- Reduces heat loss by half
- Dense feathers overlapping and waterproof
- Can control feathers individually
- When the temp drops its lifts the feather up to trap insulating air next to the body
- Feet are small and lined with fat and stand on heels to keep touch with ice to a
minimum
- As blood circulates the body absorbs
some heat before reaching feet
- On a warm day, a dog pants and some of
the water on its tongue evaporates. This
evaporation has a cooling effect that is
caused by latent heat transfer
3. The water balance of an organism is
important
- Most organisms will die if they become dehydrated with a few exceptions
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- The club moss can lose 80-90% of its water without dying
- May look dehydrated but next time water becomes available, the club moss
rehydrated, regains chlorophyll and resumes physiological activities
- Another notable exception are tardigrades (water bears)
- Small (~1mm) invertebrates can lose about 80% of their water and survive
- Toughest creatures on earth
- Tolerate many abiotic stress
- 6 environmental conditions they can tolerate:
- Lack of water (curls into ball and slows metabolic for up to decades)
- Survive super heat(150 degrees celsius)
- Super cold (-272.8 degrees celsius)
- Survive pressures (100 mega pascals)(can survive 600 mega pascals)
- Can survive the cold vacuums of space
- They are extremophiles
- Ridge to Vally water conservation system:
- Water conservation must begin at the ridges from the top
rather than letting the water flow all the way down the hill
- Make trenches
- Replenishes ground water as well
a) Water conservation by plants
- Plants must open their stomata (left-side image) to obtain
carbon dioxide for photosynthesis; however, whenever the
stomata are open, water vapour will escape to the
atmosphere
- Therefor plants need to budget for water loss
- In arid regions, plants need to be especially well adapted to conserve water \
- Thicker boundary layer lowers water loss (hairs on the leaf)
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- Another adaptation is to have a thick waxy cuticle covering the leaf
- Water can also evaporation from epidermal cells when the air is very dry. The waxy
cuticle prevents this from happening
b) Water conservation by animals
- Organisms living in drier regions have ticker skin or skin coverings like a turtle shell or
scorpion exoskeleton
- It increases the resistance to evaporative water loss, which is measured in S/cm
- Nocturnal Activity
- Behaviour can also be adapted to minimize water loss in arid environments
- Active at night where the air temperature is cooler and theres no sun
- Physiological Adaptations
- e.g Kangaroo rat
- Metabolically convert carbs and fat to
water (co2)
- Thick skin few sweat glans
- Produce very concentrated urine
- Kangaroo rat to generate internal water
through metabolic activity
- In contrast, the only source of water for the
lab rat is through drinking and eating
- Kangaroo rat has nocturnal activity
Chapter 5
1. Organisms obtain energy from sunlight, inorganic chemical compounds or
consumption of organic compounds
- Energy is required for reproduction, growth and maintenance
- The black arrows in this figure illustrate
the biological trade-off among these
three processes
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- If there is not enough energy for physiological maintenance, then the organism will
start to decline, stop growing and not reproduce. If there is some energy remaining
after the needs of maintenance are met, then there is a trade-off between growth and
reproduction
- In female mammals puberty will be delayed in individuals that have not taken in
enough energy
- In contrast, some plants in this situation will stop growing and divert their energy into
reproduction
- Cant move so they every energy to make new offspring in new location
a) Autotrophs obtain energy from solar radiation or from inorganic chemicals and
convert it to chemical energy (organic molecules)
- Two categories: autotrophs and heterotrophs
- Autotrophs can fix carbon dioxide to build energy-rich molecules such as sugar
- i.e. Photosynthesis
- Can be aquatic or terrestrial
- Many bacteria can fix carbon dioxide using energy from inorganic chemicals; this type
of autotroph is also called a chemotroph
- The lettuce sea slug is a very unusual autotroph
- Most sea slugs are herbivores but some are carnivores
- The lettuce sea slug uses photosynthesis
- Feeds on algae and retains functional chloroplasts in its digestive system for
several moths
- Solar radiation can penetrate through to the gut where photosynthesis takes place
b) Heterotrophs obtain energy by consuming organic compounds made by other
organisms
- Cant fix their own carbon
- Need to eat
- Herbivores are divided into five categories, which should be familiar to you
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- Herbivores can be further classified into frugivores (fruit-eaters), granivores (seed
eaters), nectivores (nectar feeders), and folivores (leaf eaters) from google
- They typically consume terrestrial plants, aquatic plants or algae
ii) Predators
- Capture and kill their food
iii) Omnivores
- Eat both plants and animals, whatever is more easily obtained
- Common combination is to eat fruit, nuts, insects, small arthropods, fungi, and
smaller animals
iii) Detritivores
- Eat detritus (organic material derived from dead organisms in various stages of
decomposition)
- Mold, fungus, sea slugs, bacteria, sea star, millipede and earthworm
v) Parasites
- Consume living organisms but don’t necessarily kill them
- Parasitic plants (holoparasites): unusual heterotrophs
- Parasitic plants usually start out photosynthetic and then lose the ability after they
establish a connection with a host
- The corpse flower, which feeds from tree roots in Mayalsia and Indonesia
- Hemiparasitic plants
- Obtain water and nutrients from a host plant but can also photosynthesize after
they connect to the host
- Mistletoe
- Lichen: Symbiosis between greening or cyanobacteria (autotrophs) and a fungus
(heterotroph)
- Made up of green algae or cyanobacteria and a fungus
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- Green algae and cyanobacteria are photosynthetic
autotrophs but fungi are heterotroph
- Best of both worlds
2. Radiant and chemical energy captured by
autotrophs is converted into stored energy in carbon-carbon bonds
- 3 stages to know
- Rubisco fixes CO2
- Chemical energy comes from ATP
and NADPH (Fixing CO2
consumes energy)
- The product are molecules with CC bonds like sugar (carbon is
purple)
- All autotrophs use this to turn CO2
into carbon based molecules (cycle)
a) Photosynthesis
- Chemical energy is stored in C-C
bonds or organic compounds
- 3 types of photosynthesis
i)
C3 Plants
- Occurs in the mesophyll cells
- The carbon dioxide fixed in the Calvin cycle is fixed first into a molecule with 3
carbons
- The problem with C3 is that rubisco can react with
CO2 and O2
- Calvin cycle fixes CO2 to make sugars
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- Photoresperation uses the same enzyme but consumes sugars and generates CO2
- Becomes a problem when temp increases
- As temp increases photosynthesis increases but Photo desperation is higher than
photosynthesis so plants consume more energy than they generate
ii) C4 Plants
- Circulatory tissue (xylem and phloem) are
surrounded by sheath cells
- CO2 joins with C3 to form C4
- More efficient at higher temperatures
- In the mesophyll CO2 is fixed while the Calvin
cycle occurs in the sheath cell
- More CO2 in the bundle sheath cell the O2
- Therefor rubisco reacts with CO2 and the Calvin
cycle proceeds and the plants produce sugars
- Photoresperation is reduced by keeping rubisco
away from oxygen
- C4 photosynthesis seems to be an adaptation to high
temperatures
- It has evolved independently in 19 plant families,
mostly grasses
- Because C4 fix CO2 in the mesophyll cell and dont under go the calvin cycle until the
carbon reaches the bundle cheats cell C4 plants can photosynthesize when the
stomata is closed
- Good in hot environments then water loss is
reduced with closed stomata
iii) Crassulacean acid metabolism (CAM)
- Second strategy for high temps
- Temporal separation between CO2 fixation and
photosynthesis
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- Happens in mesophyll but and night when stomata is open the plant can take in CO2
and fix it into a C4 and this is stored in the vacuole
- At night looses less water
- CAM plant have closed stomata in the day and shuffle C4 to Calvin cycle for photo
synthesis
- High CO2 in the day suppress photoresperation
- Cam plants are found in arid and saline environments
- Pineapple, cactus
- Also some epiphytes and aquatic plants and ice plants
b) Chemosynthesis
- Oxidation of inorganic generate electrons
- These electrons and ATP and NADPH and
CO2 generate organic molecules
- Oxidation of these chemicals on the right
generate drive for the fixation of carbon
through the calvin cycle
3. Heterotrophs have adaptations for acquiring and
assimilating emerge from a variety of organic sources
- For example glycolysis (breakdown of carbs)
- The breakdown of glucose consumes two units of chemical
energy (2 x ATP). However, further breakdown generates six
units of chemical energy (2 x NADH and 4 x ATP
- Heterotrophs eat to obtain energy
- Catabolic breakdown of organic molecules in food (such as
carbohydrates, lipids and proteins) provides the organism with
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energy.
- Enzymes break large carbohydrates into smaller molecules including glucose
a) Basic Food Chemistry
- Water in food does not provide energy
- Dry matter consists of organic
and inorganic component
- The inorganic components of
dry matter do not provide
substantive energy but they are
a source of enzyme co facts
(zinc and copper)
- In this flow chart, micromolecules include mineral ions
(e.g., Fe3+, PO43- and NH4+)
and macromolecules are larger
mineral complexes
- Energy is derived from the organic components when they are digested/broken down
- Different types of organic matter contain varying amounts of energy
b) Strategies for obtaining and digesting food
i)Archaea, Bacteria, Fungi
- Digestive enzymes are released into the
environment to break down organic
matter into smaller, soluble molecules
that can be transported across the
organism’s cell membrane
- The original organic matter could include
dead plants or animals as well as
pesticides and oils
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- Example oil spill eating bacteria
- Mechanical methods cant get all the oil
- Waiting for microorganisms to remove it themselves take to long
- What if the bacteria could eat faster?
- Enhance natural biodegradation by giving microbes everything necessary to eat
the oil faster
- Breaking the oil to smaller droplets
- Help them grow faster by growing them in the lab
- Supply them with phosphorus and nitrogen and delivery nutrients directly to the
bacteria
ii) Herbivores
- Plant Material is high in fibre an easy to
find but low in energy
- Herbivores spend relatively little energy to
find and obtain their food
- Plants contain a lot of fibre but little energy
- Herbivores need to consume a lot of food
(small portions all day long) grazing
- They have longer (and sometimes more
complex) digestive tracts
- Takes longer to digest and breakdown plant material so more energy is extracted
before waste is excreted
- Ruminants have a four chambered stomach in which food is broken down prior to
entering the intestine
- Food enters the rumen, where bacteria help to break down the food
- The product of this preliminary digestion is called cud
- Cud moves from the rumen back up the esophagus and into the reticulum
- From here, the ruminant can regurgitate the cud and use its teeth to break down
the food into smaller particles
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- Chewed cud travels through two
other stomach chambers before
entering the intestine. Digestive
acids in these chambers help to
break down the food further. The
symbiotic relationship between
bacteria and ruminants was the
first digestive symbiosis that was
discovered. We now know that all
animals have symbiotic bacteria in
their digestive systems
- Coprophagy: Eating ones own or
anthers feces
- Get more nutrients
- Termites rely on microbes in their digestive tract to break down the wood on which
they feed
- Termites will eat the feces of their colony-mates to replenish their gut microbiome
- Rabbits also do it
- Rabbits produce two types of feces: hard pellets and soft cecotropes. They eat
their own cecotropes
- The material passes through the digestive tract a second time, which maximizes
the extraction of nutrients from their food
iii) Predators
- Prey are hard to catch bit high in energy
- Grazers, predators eat infrequently but, depending on the species, the range of
feeding frequency ranges from eating very few minutes to eating every few months
b) Other adaptations for obtaining and digesting food
- Can be morphological (include the modified mouthparts of insects that are
specialized for chewing, sucking, piercing, etc and beak shape) , physiological or
behavioural
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- Evolution of ecotypes may arise due to on-going specialization of morphological
adaptions to obtain food
- The upper and lower crossed beaks form a space (called a groove) that helps them
to pry open the scales of conifer cones, making it easier to extract the nutritious
seed that is inside
- Researchers found five adaptive peaks for
the Crossbills
- An adaptive peak occurs when the
organism’s fitness is highest
- Fitness it highest when the shape of the
bill ‘matches’ the shape of the cone
- Birds feeding on Western hemlock have
the highest fitness (measured as survival
on this graph) if their bill depth is about
8.4 cm and their groove width is about 1.98 mm
- Physiological adaptions can include
changes in digestive activity
- Pine warblers typically eat insects
during the breeding season, when they
live in the temperate and boreal forests
of North America,They migrate to
Central and South America in the
winter, where they typically eat fruit
and nectar
- The physiology of the digestive system
shifted depending on the food source
- When birds were fed fat-rich seeds, the rate of food passing through the gut slowed
down (middle graph, red bar; it took longer for the food to pass through), allowing for
efficient extraction of fat. In contrast, when the birds were fed low-fat fruit, the
pancreas produced less lipase (right-side graph, green bar)
iii) Behavioural adaptation (tool use)
- Shells and sticks
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- Rocks to open seeds
- Ravens drop nuts infant of cars
- Cockatoos fill mouths with leaves to help twist open nuts
Chapter 6
- Species were thought of being immutable with no change
- God created them
- Stayed the same for all time including humans
- In 1813 George Cuvier discovered the notion of extinction by looking at mammoths
- Thought at first they were elephants
- Teeth morphology in the fossils were different
- Was able to say species disappeared
- Charles Darwin and Alfred Wallace discovered the concept of evolution
- Were ecologist at first
- The boat Beagle
- Key Concept 1: What is evolution
- Evolution is descent with modification
- Evolution is allele fréquence change
- Populations evolve individuale do not
- Evolution is at the population level, individuals do not evolve
- Horses were first explored
- Animals were originally small
- Size of a dog
- Lived in a forest and was a browser
- Today horses are grazers in open fields (demands a larger animal to escape more
predators)
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- Feet grew
- Close ancestor is a
Tapper
- Had toes
- As courses evolved
the toes fused
because its better to
run
- From bottom: 50 MYA, 35, 15,
8 and 1
- The horse didn't go from small
to big as if there was progress
in evolution along a linear track
- When evolution happens (change in gene frequencies) it happens
along the whole route
- The real evolution is a branching tree
- Each green line is the origin of a species and the end is the extinction of that
species
- In the myosin we got large grass lands so it was the pressure for evolution
- No continuous line yet
- Scientist looked at fossils of a stickleback fish in a single lake
- 10 million year old fossils
- 250 year intervals
- Layered fossilized fish
- Clear example of having a heavy armour that slowly
disappears
- Lost armour from ocean to lake
- Species do change! (with time)
- When you have a change in allele frequencies it represents evolution
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- Deep time: things change gradually and things were around for millions of years
previous to us
- How fast to alleles change?
- Horses had 50 million years
- Fish had 10 million years
- Genetic variation you can look at coat colour (horses)
- Multiple colours suggests (phenotype) has underlying genetic representation
- Was colour heritable?
- Doesn't seem like theres much selection in horses because theres many colours
- Mice have a mix in coat colour
- Light colour and dark colour with some in-between
- Colour in mice are selected for or against
- Mice are good prey for many animals
- In dark rock habitats (lava rocks) mice are more likely to have darker fur (pocket
mice)
- Lava rock is not continuous in the whole habitat so light and dark in different parts
same with the mice
- Strong selection must occur on variation that exists with arises from mutation
- Jaguars can be dark or light
- Same with most other animals
- Same gene in these mammals are responsible for fur colour
- Evolution acts on frequencies variation in the allele that comes by mutation and can
come rapidly (can see it in our life time)
- Key Concept 2: What are the mechanisms of evolution or what causes the allele
frequencies in a population to change over time
- Mutation
- Natural selection
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- Genetic drift
- Gene flow
- Just like coat colour, teeth
morphology is also important in
animals
- Shows what kind of diet they
have
- Teeth variation in all animals
- Individuals in populations differ in
their phenotypes
- Mutations are the raw material for
creating variation in a population
- Arise from error in cell division,
exposure to chemical, mechanical damage or high energy radiation from the sun
- Mutations are rare
- Elephants have have incisors that are modified to the tusks (big tooth growing out)
- Used for digging
- Tusks make the animal venerable for poaching
- Buried in the jaw so animals need to be killed
- There exists mutations for the tooth that make them smaller because of poaching
- Tusklessness
- Recombination and independent assortment of chromosomes during meiosis
also produce different genotypes within a population
- Offspring have combinations of alleles that differ from parents
- Recombination produces new combos of alleles
- Doesn't add variation in the population, mutations need to do that
- Mutation provides the raw material on which evolution is based, while recombination
and independent assortment rearrange the raw material into new combinations
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- Natural selection is the driving force in evolution
- Birds beaks are comparable to teeth
- We can see variation
- 3 Types of natural selection:
- Directional: Individuals at one phenotypic extreme
(e.g large size) are favoured
- Stabilizing: Individuals with an intermediate
phenotype are favoured
- Disruptive: Individuals at both photopic entries
are favoured
- Directional selection was one of the first
observations of natural selection in a wild
population
- Shift in beak size
- Larger seeds survived in a drought so only
bigger billed birds could eat
- Stabilizing in plants
- Smaller galls have stronger selection so
woodpeckers dont eat it
- Disruptive has variation in both
- Polymorphism for large and small bills
- Big to open seeds small to handle small
seeds
- Genetic Drift: Occurs when chance events
determine which alleles are passes to the next
generation
- It is significant only for small populations
- By chance some alleles will be fixed
(permanent) in some populations or some
will disappear or be lost
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- Random event that change the allele frequency in a population which means
evolution
- Gene Flow: Alleles move between populations via movement of individuals or
gametes
- Populations become more similar
- New alleles can be
introduced into a population
- Those white things you
blow on and they fly away
- Animals that are moving
- Plants when they send
there seeds/gametes out
- Marine organisms can move in the plankton
- Insecticide resistance
- Gene/allele for resistance starts in one population and can move to others
- Growth in frequency to a high level you need to apply selection pressure to see it
(insecticide)
- Many female elephants lack tusks
- Tusk-less males are rare because they fight with them and need them to survive
- Tusks are harvested for the ivory trade
- Which process is least likely to be the direct cause of appreciable change in allele
frequencies over short periods of time? Mutation
- Which process changes allele frequencies by chance alone? Genetic drift
- Key Concept 3: Natural selection is the mechanisms of adaptive evolution
- What is adaptive evolution?
- Adaptations results from natural selection
- Adaptive evolution can occur rapidly
- Adaptations are not perfect
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- Large massive beak on a finch
- Hunt hard shells
- We call these predators durophagous predators (hunt hard things) (Hyenas hunt
bones)
- Dark coat on jaguar is a good adaptation to sneak in shadow
- Adaptations are traits that allow increase fitness in an individual in a population
- Reproduce to be more successful
- Natural selection is not a random process
- Natural selection favours individuals in a population with certain alleles
- Selects for traits tat confer advantages
- Alleles increase in frequency over time
- Animals that specialize on hard shell prey will have selection for more force on a claw
- The prey is being selected by the crabs to have thicker shells
- Thin lips on shells with no crabs thick lips on pressure from crabs
- Horns and antlers
- Male use it in combat to gain reproductive access to females
- Bighorn sheep populations have been reduced 90% by hunting, habitat loss and
introduction to domestic cattle
- Hunting is now restricted in North America; permits to take a large “trophy ram” cost
over $100000
- Horn size is heritable and decreasing with hunting pressure
- Adaptations are not perfect
- Natural selection does not result in a perfect match between organisms and their
environments
- Environments are constantly changing, and there are constraints on evolution:
- Lack of genetic variation
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- When you have a strong selective pressure and theres no mutation theres no
evolution
- Evolutionary history
- Wales need to come up for air, evolve from a land mammal
- Constraint because they need to come up and get air even tho prays deep below
- Ecological trade-offs
- Strong claw but very slow on crabs
- Adaptive evolution is driven by ecological interactions, organisms interacting
with one another and their environment
- Natural selection and evolution is the basis for understanding ecology
- Key Take Home Message:
- Ecology is about populations that make
up communities formed into ecosystems
all interacting with each other
- Evolution represents change in allele
frequency of a population of any species
- Adaptive evolution can occur rapidly
- Long legged lizards run faster
- Cant hold onto leaves long
- Short legged lizards can go on thinner
branches (firm grasp)
- Bigger fatter lizards have hairs on toes to
hold themselves up on leaves
- Key Concept 4: Long-term patterns of evolution are shaped by large scale
processes:
- Speciation
- Represents the splitting of 1 species into 2+
- Adaptive radiation
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- Extinction
- Mass extinction
- Rock pocket mice
- Strong selection by the predatory owl for
camouflage
- If there was a river to laminate gene flow
between the dark and light population so
no mice could move for many
generations then we start to see
speciation potentially
- You can still have genetic change in a single parental line but genetic differences is
the chance in red and purple and yellow and purple
- Barrier needs to remain in place
- Wolves and dogs
- Connected reproductively even though their separation occurs a really long time
ago
- Ecological seperation
- Still gene flow
- Reproductive barrier can be ecological or geographic or physical
- River
- Mountains
- Continental drift
- Repeated speciation events increases the number of species in a group (adaptive
radiation)(multiple speciation events in a group)(different beaks)
- But some species are also lost to
extinction
- An evolutionary tree is a branching
diagram that represents the evolutionary
history of a group
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- Evolutionary tree or bush
- Involve multiple speciation events and
extinction events
- Monophyletic: Single common ancestor
- Any point on the tree where it
diverges is a hypothetical common
ancestor
- Horizontal lines are evolutionary
lineages
- Can still have changes in allele
frequency but no branching
speciation
- Top point is the pinniped common
ancestor where it diverges (red
circle)
- Evolution is observed patterns of
change
- Bacteria and arches
- Multicellular life (red algae)
- Animal life
- Big evolutionary patterns in terms of change
- The rise of one group was often associated with the decline of another
- 265 million years ago, reptiles replaces amphibians as the dominant terrestrial
vertebrates
- 66 million years ago the reptiles were replaced by mammals
- 5 mass extinction events with a drop in species diversity
- The fossil record documents 5 mass extension events; large portions of earths
species went extinct in a relatively short time (a few million years or less)
- Each was followed by adaptive radiation: increased diversity of the surviving
groups
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- The last was the best
- Extinction rates on the graph
- 3-5 families going extinct before mass extinction
- Extinction leads to speciation
- Low extinction rate in Cenozoic
- Dominated by mammals instead of dinosaurs
- 65-66 Million years ago
- Key Concept 5: Ecological interactions and evolution exert a profound
influence on one another
- Evolution can alter ecological interactions
- If a predator evolves a new way to capture prey, the prey may go extinct, decline or
migrate or evolve new ways to come with more efficient predators
- Similar changes can occur among species that compete for resources
- Evolutionary changes over long time scales can have a profound effect on ecological
interactions
- Example; The adaptive radiation of terrestrial plants altered all aspects of life on
land, from soil stability to sources of food available to other organisms to untruent
cycling
- Land plants first colonizing earth
- Because evolution can occur over short time
periods it suggests that reciprocal feedback
between ecological and evolutionary factors
can also occur over short periods of time
- Feedback effects can operate at multiple
levels in an ecosystem
- Hybrid species between 2 sunflowers that are
fertile
- Capable of colonizing different environments
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- Then the environment selected for species more suited for the environment
- Not sure if daughter can breed with its parent species
- Cant understand ecology without understanding evolution
- Populations evolve in time
- Evolutionary change influences populations and populations will influence
evolutionary change
- Suppose that, following the experiments by Dodd, Drosophila pseudoobscura are
raised on one of two diets (starch or maltose) for many generations. Once they have
adapted to the new food sources, individual females from the starch treatment are given
a choice between a male adapted to starch (a starch male), or a male adapted to
maltose (a maltose male). When 50 females have chosen a mate, the experiment is
repeated with females adapted to maltose. The results are in the table. Which
conclusion is best supported by the data? Partial reproductive barriers evolved in
both directions of the cross
Chapter 7
- Life history is in fact an adaptation
- Based on timing and decisions on when these
things (having babies) is happening
- Key Concept 1: Life history patterns vary
among species and within species
- We take 40-70 years
- Fruit flies take 50 days
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- Cicada takes 17 years in the ground to
become an adult (winged) for 4-6 weeks
- Plants also vary
- Tree longer than a dandelion
- Tree does not start reproducing until its 15
years old but can live for over 200-500 years
- Variation in all organisms when it comes to life
history strategies
- Allocation: The relative amounts of energy
or resources that an organisms devotes to
different functions
- Survival can be juvenile survival and adult
survival
- Reproduction can be age of maturity and
reproductive life span
- Frogs life history is divided between an aquatic
state and a terrestrial one
- Resulting in several evolutionary decisions
- Our genomes continue into the population
when we reproduce
- Life history events are heritable and show variation around species and within
- Duration of tadpole
- Timing of metamorphosis
- Different frogs have different genetic and environmental differences
- Tadpoles eat algae
- Wanna leave the pong before it dries up and predators come so tadpole stage is
short
- From gills to lungs
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- Camouflaged tadpoles can stay longer in the
pond
- Variation is life history among species
- Survival is low in an aquatic environment
- Sometimes the tadpole stage is skipped
- Environment is always shifting which adds
strong selection pressure or you need to
commend to the selective pressures
- Phenotypic plasticity may result in a
continuous range of sizes or discrete types called morphs
- Phenotypes comes from a single
genotype
- Single genotype with environmental
input results in many different
phenotypes
- Spade foot toad is an example of
both
- Lives in desert environments
- If a pond remains a pong before it dries up the tadpole will grow to a bigger size,
if the pond starts to dry then the tadpole is cued in and shift into development
and turn into a frog earlier at a smaller size
- Phenotypic plasticity is timing of metamorphoses
- Tadpoles are the same genotype
- Adult phenotypes differ in size from
accelerated
- Spade foot has another morph type, omnivore
and carnivore which goes faster and larger
- Can be cannibalistic on other tadpoles
- Corals are colonial animals
- Made up of small polyps on the tentacles
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- one individual is a polyp
- Asexual at first
- Then they decide is its gonna be male female
- Takes place is the ocean
- Key Concept 2: There are trade-offs between
life history traits
- Allocate limited energy or resources to one
function at the expense of another
- Trade offs between number and size of off
spring, Trade offs between organisms parental
care (birds) and without (lizards)
- Trade offs between reproduction and survival
- After growth energy is toward reproduction
- In male flies as body size increases the life span expected increases
- Males with mated females have a greater life expectancy than males with virgin
females
- Wont try as hard with a non virgin
- Spend more energy with a virgin
- With pine trees they can either grow bigger or reproduce more with more pine cones
- Maturity in 10-15 years
- Larger trees are better than smaller so we
should cut down big trees!
- At reproduction goes off spring quality
- Many?
- Few?
- Palm trees can make 30 seeds
- Heavy
- Dandelion seeds are light
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- After off spring quality is parental investment
- High?
- Low?
- Parental Care: Invest time and energy to
feed and protect offspring
- Some frogs leave their tadpoles some
who skip tadpole stage guard their eggs
- Clownish protect and clean nest
- Some plant seeds develop on the plant
while the parent feeds and rovides it with
water (mangrove)
- Key Concept 3: Organisms face different
selection pressures at different cycle stages
- What are the benefits and costs associated
with small size in early life cycle stages
- How do adaptations at specific stages in a
complex life cycle may benefit the species
- Coral can be in the planktonic or nonplanktonic/
benthic stage
- Benthic have protective skeleton
- Planktonic stage can sometime be skipped and go straight to baby small crabs
- Benefit to having a larval stage (complex life
history) Each bar is duration of a species
- The longer the bar the longer the species
existed
- Nonplanktonic is shorter than when you have
the larval stage
- Key Concept 4: Reproductive patterns can
be classified along several continua
- As animals become larger they tend to have
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fewer offspring but their life span is
longer
- Short life spans need more off spring in
a shorter period of time
- Iteroparous and Samelparous
- Pacific salmon spend majority of their life
out at sea and they return to birth place
in a stream and mate and die
- r/K Selection Theory:
- r- selected (live fast die young):
- Short life spans, rapid development, early mutation, low parental investment,
high reproductive rates
- Most insects, small vertebrates such as mice, weedy plant species
- K- selection: Populations that are at or near K, the carrying capacity for a
population
- An advantage in crowded conditions
- Long lived, developed slowly, late maturation
- Want offspring to be competitive in their environments
- Invest heavily in each offspring, low reproduction rates
Chapter 8
- Many animals live in groups
- Behaviour ecology explains behaviour in evolution and ecology
- Advantage of living in a group is that you can take down dangerous prey
- Most eating and killing in a lion pride are females
- Males seemingly dont do much
- Protect
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- Sex
- Kills the cubs
- If we understand some unusual behaviour we can get a long with some fierce
animals
- Behavioural Ecology: The study of the evolutionary basis of animal behaviour
- Behavioural decisions, and executing these decisions have costs and benefits
- Foraging, mating and living in groups
- Key Concept 1: Evolution is the basis for adaptive behaviour
- How does natural selection lead to adaptive behaviours
- How does the environment interact with genetic to influence behaviour
- How do alleles change to bring about adaptive evolution
- Proximate Causes (immediate) - Or how the behaviours occur
- Evolution has selected for dogs that can raise eye brows and give eye contact (eye
contact)
- Dogs that give puppy eyes get more adopted
- Ultimate Causes - Why the behaviour occurs; The evolutionary and historical
reasons
- Behavioural ecologists mostly focus on ultimate causes
- Long run experiment starting in 1959
selecting for a behaviour (tameability)
- Domesticated dogs have extra muscles to
raise eye brows and wolves dont
- How were dogs domesticated?
- Natural selection shaped animal behaviours
- Heritable variation
- Behaviour is determined by genes
- Cockroaches learned to hate the taste of
glucose because it was in the killing bait
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- Mutations that affect the taste receptor neuron
- Insecticide selected avoided glucose and corn syrup
- Both ate fructose (profitability eqn)
- We can study complex behaviour in mice and
rats
- The Hoekstra lab
- Burrowing behaviour
- Selected for more elaborate burrows
- Escape tunnel thats closed off
- Oldfield mouse is related to the deer mouse
- Deer mice just have a short entry tunnel
- Both tunnels are genetically determines
- Deer mice and Oldfield mice produce fertile
hybrids
- End up with all the nests (F1 generation)
have the complex escape tunnel
- F2 generation with a backcross is half half (mate
with offspring so 3/4 Oldfield mice)
- Although few studies have identities the genes,
many behaviours are known to be heritable and
most are influenced by other genes (behaviour<—
>genotype)
- Key Concept 2: Animals make behavioural
choices that enhance their energy and reduce risk of becoming prey
- Cost benefit analysis
- Animals will maximize profitability
- Visual
- Mathematical
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- Conceptual
- Prey are not homogeneously spread
- How do you maximize your profitability?
- Swallowing is handling time
- The further the bird moves the more
energy used
- Energy levels off
- At a certain point realizes the gain isn't
worth the effort
- As your foraging your always investing
energy
- Even before you obtain energy you are
paying for what
- Blue - Red - Gold
- Starts after total energy obtained
- Starts at 0
- After plate on gold it goes back down
- Animal should stop forging at the gold
maximum point (perfectly in tune)
- Animals will enhance or at least try to
- Trade offs make it more messy
- Predators
- Environment
- Physiology
- Optimal Foraging Theory: Animals will maximize the amount of energy gained per
unit of feeding time and minimize the risks involved
- With predators out the bird feeds less
- Optimal foraging theory does not apply as well to animals that eat mobile prey
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- The assumption that energy is in short
supply, and that this dictates foraging
behaviour may not always hold
- Resources other than energy can be
more important such as nitrogen or
sodium content fo food
- Key Concept 3: Mating behaviours
reflect the costs and benefits of
parental investment and mate defence
- Why do males often look different from
females
- Male competition for mating
- Females will choose males to breed
with
- Longer tales the more nests
- Control was gluing extra tail feather
(control 2)
- Blue footed boobie dances
- If you live in a flock or group your survival rate
goes up
- Predator cant pick out just one person
- Series of events
- Lions are always following zebras so zebras stay
together
- More time searching for food with larger flocks
- More mouths to feed \More time flying with
larger flocks
- Lions kill their cubs and reduce the number of people in their pride
- In genetics
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- Textbook
Chapter 9
1. Populations are dynamic; they
vary over space and time
- Distribution is the geographic area
where individuals of a species are
present
- Abundance is the number of
individuals of a species found in a
given area (how many are found there)
- Members of a population interact
- Competition for resources for example
- A population of bird living in southern Australia is a
different population from the bird living in easter
Europe
- Not so clear if the population in Australia is the
same or different from the one in New Zealand
- All depends on the extent to which individuals interact
- Year round individuals are distinct populations because they
dont move
- Therefore the time at which you census your populations and
look at these interactions can matter
- Summer populations can be different from winter populations
- Population size and population density are also important
- Look at the monarch
- Population size is how many million butterflies (41 million fewer in 2017)
- Population density is the size/unit area
- Density hasn't change very much
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- What is an individual
- Individuals need to interact to define the population
- Some plants like aspen trees are Clonal (clones)
- Many trees are clones representing a single individual
- Genet: Single genetic individual
- Entire aspen grove is one genetic individual
- Ramet: Physiologically independent members of a
genet
- Compete for resources
- In the pic 1 genet gave rise to 6 ramets
- Clones can rise in 3 ways
- Budding
- Duckweed daughter plants bud off from
mother plant
- Apomixis (plant) or Parthenogenesis (animals)
- Development of a seed/embryo from an
unfertilized ovule/egg
- Horizontal spread
- Above or below ground stem
- Population abundances can be estimated using 3 techniques
- I) Area-based counts
- Use quadrants or sample plots with many replicates (2 sided
square)
- Works best for: immobile (sessile) organisms or species with a
fairy even distribution in a small defined area
- II) Distance methods
- Line transects
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- Draw the transect on a map of an area
- Walk along the trances, record the perpendicular distances to individuals of the
species of interest that you can see (hear)
- A number of formulae are available to estimate abundance in the area sampled
(these formal are not testable in the class)
- Suitable for late organisms (trees) or mobile
ones (birds)
- III) Mark-recapture species
- Use a formula to estimate population size
- Catch a number of the species, mark them,
release them, wait, catch another batch and
count to see how may were recaptured then
use formula to estimate
- Can be repeated multiple times to get a better
estimate
- MEMORIZE FORMULA
- N=(M1xM2)/R
- Use of equation assumes:
- No change in population size between capture
dates
- No births, deaths or immigration
- Each individual has an equal chance of being caught
- Traps need to be placed to catch a random sample of the population
- Marking does not effect survival or behaviour (neither trap happy or trap shy)
- Mark does not make population more visible to predators or no tasty bait
- Marks are not lost between capture dates (but they do not have to be permanent)
- Recaptured individuals provide information about the dispersal or migration of the
individual. For example, a bird marked at the Long Point Bird Observatory might be
found in the Yukon during the summer and in Cuba during the winter
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2. Distributions and abundances of species vary across their geographical range
- a) Dispersal links populations
- Very rare for all embers of one species to like in a single population
- Populations are connected through dispersal
- Migration: The mass movement of individuals from one region to another, typically
seasonal i.e. the arctic tern travels from Canadian arctic to the southern tip of Chilli
each fall and returns in the spring
- Dispersal: The movement of individuals away from one another, usually across
generations i.e. the stripped skink kits will stay with their mom for a year the
disperse and establish their own area
- b) Dispersion: Spatial arrangement of individuals within a population
- Dispersal is not the same as dispersion which describes the relative locations of
individuals within a population
- Regular (uniform) happens
when individuals are
equidistant from another (
- Random is when some
individuals are closer together
and others are at varying
distances from each other
- Clumped is when individuals are found very close to each other ‘
- Determining the dispersion pattern of a population depends on the choice of scale
(area covered) during population
census
- The larger the area the more
likely they will appear clumped
- There can be patches within
patches within patches until a
regular dispersion is seen
- Scale matters
- The patch within a patch is seen
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in species that have narrow
tolerances (particular habitat
for example)
- Many species have patchy
distributions of populations
- Patch with a general region
- Habitat fragmentation has
created a metapopulation: A
group of geographically isolated
populations linked by dispersal
- Population distributions vary over time
- The collection of fragmented populations is
the metapopulation
- Population fragmentation could result in
reproductive isolation but dispersal
maintains populations across patches
- If dispersal does not link the patches local
ecotypes may evolve
- Computer models are used to predict current or future distributions of species
- Faster
- Document abiotic and
biotic factors in each cell
in a grid
- Then knowing the
physiological limits
(favourite food type sand
preferred nesting) a
computer model can
predict distribution
- Know what the species
need to survive then can predict areas where they live
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- Circles are ones where the species has never been seen
3. Habitat, history and dispersal limit distribution
a) Habitat
- i) abiotic environment
- Each species has unique abiotic factors it can tolerate and if a habitat is not
suitable the species will not thrive
- If the abiotic resources are available but patchy the distribution will also be patchy
- ii) Biotic Environment: Competition
- Competition fo water and nutrients may lead to uniform distribution
- iii) Biotic Environment: Behaviour
- Behaviour could result in clumped dispersion if individuals prefer to live in groups
- Meerkat living in colonies
- Behaviour have also result in regular dispersion
- Birds fight for territories leading to regular distribution of territories
- Some birds may be forced to breed in territories with poorer resources
b) Evolutionary & Geological History
- Dispersal limitation reduces an organisms ability to get a suitable habitat that is far
away
- Therefor the distribution of some species is determines more by when and where
they evolved than where suitable habitats can be found
- For example, polar bears evolved from brown bears and they are found exclusively in
the arctic
- Polar bears need sea ice to catch their food which is only found in the Antarctica but
only found in northern Canada because of global warming
c) Dispersal
- i) Dispersal Mechanisms: Animal
- Many modes of dispersal
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- Animals may more more
actively or passively
- Active includes: Walking,
swimming, flying, etc
- Passive includes: Drifting in
water or air currents (spiders
ballooning, EN web then move
in the wind via electrostatic
forces)
- Phoresy: One organism carried by another (non-parasitic)
- Also active dispersal
- Hitchhiking a ride
- Suckerfish on a sea turtle
- Might be evolutionary precursor to some parasitic relationships
- ii) Dispersal Mechanisms: Plant
- Adhesion, ingestion, flotation, wind and projection
- All plants disperse passively
- Adhesion: Seeds can be sticky or have hooks that attach to fur of passing animals
- Ingestion: Plants can
entice herbivores to
console fruit and the
seeds are dispersed in
the poop, often far
- Wind: Some plants
produce seeds with their
own parachute that
catches wind currents
(dandelion)
- Floatation: Plans near shore have seeds that float in water
4. In metapopulations, sets of specially isolated populations are linked by
dispersal
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- Metapopulation: A group of interacting populations of the same species
- Separated by space
- Examples near prairie potholes (shallow holes of water)
- When summer comes connections between potholes
decreases and smaller ones dry up
- By the end of summer animals that live in potholes can become distributed as a
metapopulation with one population per pothole
- Theres also bald eagle metapopulations in Ontario (yellow)
- Easier for flying animals to maintain dispersal amount sub population
within a metapopulation
- Created as cities and agriculture displaced the natural habitat and as
pesticides reduced reproduction and survival
- Extinction risk is related to the size of the fragments; they must be
large enough to support at least one breeding pair and their young
and the fragments must be close enough to each other to avoid
inbreeding within the region
- Habitat fragmentation can cause unstable metapopulations
- Getting smaller and farther apart
- Characteristics of a metapopulation:
- Source populations E>I
- Sink populations I>E
- Repeated extinctions and recolonizations
- Isolated by distance
- Rescue effect
- Populations that provide a source of new individuals (offspring that can survive) are
one in which emigration (E) is greater that immigration (I)
- Populations that los more individuals are sinks
- Smaller and further populations are more likely to be sinks (more local extinction)
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- A healthy meat population will have plenty of source populations for re colonization
of sinks
- Natural to have extinction and recolonization of smaller isolated patches within a
metapopulation
- Isolated by distance refers to the necessity of dispersal for recolonization and the
reduced ability of individuals to disperse over a longer distance
Chapter 10
1. Populations are dynamic; they cary over
space and time
a) Abundance changes over space and time
- Study on beetles that feed on golden rod
- Montezuma is always smaller than hector
- Changes over time best seen in last 2
- Some year population density is low some
years theres an outbreak
- Population size changes in response to 4 biological
processes
- Formula
- Birth, death, immigration and emigration (each can change independently)
b) Four patterns of growth
Exponential growth
i)
- Requirements: Favourable conditions and able resources
- Can accrue after a population crash due to disturbance
(density independent event) (ie.e. a fire)
- This is because it keeps a seed bank (many seeds sitting in
the soil)
- Also can happen after dispersal to a new geographic area (jump dispersal)
- Grow in new region the move and then grow and so on
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ii) Logistic growth
- Initial rapid growth
- Growth rate (r) slows due to density dependent factors
- Population size reached an EQMB (B=D, I=E) due to limited
resources (food and space)
- Starts with high r then slowly decreases
- Naturally populations rarely have this smooth s, usually a
little more rocky
- No lag because its not just a few sheep its a heard so
population started large + no predators
- Equilibrium population size fluctuates because the
carrying capacity (K) is not constant
- Oscillates around the K
iii) Population fluctuations
- Population size changes erratically
- Can be small (normal) or large (outbreak/
crash)
- Often due to density-independent factors
- Blue line is actual number
- Red is a running average
- Outbreaks = times of population explosion
- Crashes = times of rapid population
reduction
- Both density independent (lost of food or predators)
- Outbreaks can be devastating in an ecosystem (pine beetle kills the trees)
- Density-dependent factors (disease, hormones, aggression)
- White-nose bat syndrome
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- Inhibited reproduction and depressed immune system in mice when populations
get dense
- Cannibalism in viviparous fish when population density gets higher
iv) Population cycles
- Alternating high and low abundance
- Due to density-dependant factors
- Lemmings and stoats
- Predator and prey
- NRC organization that slows the
spread of an out break
- Early intervention: identify
hotspots and intervene early
so males can mate with
female
- Use of pheromones to put in traps and disrupt mating
2. Delayed density dependence can cause population cycles
- Time lag in response to good conditions
- Delayed density dependance is believed to be the most important factor that causes
population cycles
- Delayed density dependence results in a population temporarily exceeding its
carrying capacity due to a lag in response to growth promoting conditions
- For example, if there is an abundance is squirrels in the summer, owls will be well fed
but they dont reproduce until February or march of the next year
- Well fed owls will produce more off spring therefore the number of owl babies in the
spring reflects the abundance of squirrels last year, then the more owls there are the
fewer swirls will survive so the owl population will decline
- Top graph shows the population size for a species that has almost no time lag
between having ample resources and increasing its reproduction rate. Once the
population hits K (carrying capacity) it will be stable
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- The middle
graph shows the
population size
for a species
with a lag that is
short than its
reproductive
cycle. Eventually
the population
will stabilize
around its
carrying capacity
- The bottom one
shows the
regular, cycling population size for a species that experiences delayed density
dependance
3. The risk of extinction increases greatly in small populations
- The dodo bird for example only thrived on one island
- a) Fluctuations in population size
increase the risk of extinction
- Green population grew and around
40-50 years it looked stable and
overcame having a small population
size
- The red population is intermediate with
a slow start and recovered from having
a small population
- The black population never recovered
- Simulated data
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- b) Small populations are at greater risk of extinction
- We can see that small populations are just at greater risk in birds
- When the number of breeding pairs is low the risk of extinction is high
- High number of breeding pairs has a lower risk of extinction
- c) Genetic factors can put small populations at risk of extinction
- i) Genetic Drift: Chance events influence which alleles are passed to the next
generation
- If you have a population with 2 alleles (white and yellow flowers), if elephants
trampled some and killed all the yellow then yellow allele would be less apparent
- If population was small this could whip out the yellow allele
- Large populations have more variation so extinction may not occur
- ii) Inbreeding
- In small population there are fewer mates so inbreeding is likely
- Dog breeds have been inbred to favour specific traits
- Puppies have many problems to decrease survival
- d) Demographic factors
- i) Demographic Stochasticity: Chance events affecting reproduction and survival of
individuals
- Chance events crushing eggs
- Will small populations loosing eggs could cause extinction
- ii) Allee Effect: Population grown rate drops
at very low population densities
- The fewer individuals the less chance there
is to find a mate
- Fewer fish in a school means less of a
warning system to prey
- e) Environmental factors
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- i) Environmental Stochasticity: Unpredictable changes in the environment can
effect year to year changes in birth or death rate of the entire population
- Late frost and the flowers are killed before they seed
- Late frost prevents the entire population from breeding in that year
- Will less individuals can lest to extinction
- ii) Natural Catastrophes
- Freezing rain, tornados, fire, hurricane
Chapter 11
1. Populations can grow exponentially but not indefinitely
- The human population has grown very rapidly over the past few centuries
- Sustained are of
growth since the
industrial
revolution (higher
than any other
species
- No population can
increase in size
forever
- What is the human
carrying capacity
- Capacity is limited
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a) Geometric Growth
- The pattern of initial population growth
depends on the reproductive pattern of a
species
- Those species with synchronous
reproduction undergo
geometric growth (cicadas
and annual plants that
germinate, mature, reproduce
and die in a single season)
- Number of individuals during
each breeding season
- Synchronous reproduction
has evolved to align breeding
to maximize reproductive
success
- For example, raising the
young when prey are most available
- Memorize equation growth rate
- Essentially, the population size in a given year is the population size in the previous
year multiplied by the geometric growth rate
- Lambda is rarely constant over time
- Growth rate in nature is rarely
constant due to changing abiotic and
biotic conditions Table shows
changes in growth rate for 5 years
- To examine the effects if varying
geometric growth rates on a
population you can create a series of
tables
b) Exponential Growth
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- For organisms with continuous reproduction, individuals can reproduce at any time of
year so reproduction is not synchronous
- This pattern leads to exponential growth of the population
- Memorize the equation
- The change in population size over
time is equal to the number of
individuals time the exponential
growth rate (r)
- Bottom graph is the log to make it
exponential
- Rearranging the dN/dt we can get
an equation that contains a log
- Memorize
- Important to realize that this new equation can be used to calculate r for a population
using info that is the corresponding table
- R is rarely constant over time
- As with geometric growth rate, the exponential growth
rate is rarely constant over time
c) The end to exponential growth
- Eventually limited by resources (food),
space, disease, predation, etc.
- Exponential growth cannot increase forever
- Darwin realized that populations had limits
on their growth and performed a ‘thought
experiment’ using elephants as an example
- realized that the number of adults in a
population (even a growing population) was
smaller than one would predict if large
number of offspring survived
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- Elephants have low reproductive rates, one of the slowest reproducers on earth
- Has potential to reach high limits but doesn't
- Direct evidence that exponential growth cannot continue forever
2. Population size can be limited by density-independent and density-dependent
factors
- Each point on the graph represents a single population , the line is the average
growth rate
- Density independent factors
do not affect the populations
growth rate at ant population
density (left)
- Density dependent facts
cause the population growth
rate to decrease as the
population density increases
a) Density-independent factors affect population size
- Density independent do affect population
size/density but the change is usually
temporary
- Density independent factors do not
regulate population size
- Freezing rain, tornado, heat/drought,
waves, fire decrease
- Influx of nutrients, mild windier and
adequate water increase
- Weather can have density independent effects
- For many species the population varies with ambient weather conditions
- Predicted number with weather
- Climate change can have density-dependent effects
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- Birth and death rates can rise or fall as environmental conditions get better or worse
- Increase death in trees can be due to climate change
b) Density-Dependent factors regulate population size
- Density dependent factors include
essential resources (food, space,
water, mates) as well as diseases
- When resources are ample and
diseases are low the population will
increase in size
- Density dependent factors regulate
population size by inducing
changes in reproduction, death and
dispersal
- Many organisms alter their rates of dispersal
in response to local conditions
- Female aphids were put in high and low
population densities, females from each
population produced winged offspring but the
proportion was 30% higher from females in
the denser populations so they could
disperse to a new location
- This came because of the density of the local
population, density of predators, abundance
of food and abundance of mates
- Lambda and r vary with population density
- Increasing population density will result in decreasing
values for both of these growth rates
- Another way to examine density-dependent effects on
population size is show in the bottom figure
- When the planting density is low all the individuals
survive but as it increases not all survive
- Once the carrying capacity is reached density
dependent changes in population growth will result in a
fairly stable population size with fluctuations in plant
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density varying slightly with resources available
3. The logistic growth equation incorporates
limits to growth and shows how a population
may stabilize at the varying capacity
- S shaped curve
- Population starts small and theres a lag in
increase, as exponential growth increases so
does population and density dependent factors
start to slow down the intrinsic growth rate
- Causes the curve to take an S shape
- At K the population stops growing (what the
environment can hold at that time)
- Why does this S shape occur?
- Purple letters
- Same as exponential growth equation (overlap at
small population size
- At really large size the change = 0
4. Life table can be used to model population growth
- Data seen in the figure is for the human population
- The blue curve is the world population
- Light blue is an estimate
- Red is the annual growth rate of human
- When in the dar blue the r increased
- After dark blue it decreased
- Humans didn't stop reproducing the rate just decreased
- By 2100 the human population is gonna be close to its carrying capacity
- Follows logistic growth curve
- Age Structure: Proportion fo individuals in each age class
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- Juvenile (pre-reproductive)
- Adult (reproductive)
- Adult(post reproductive for some species
- Can also include eggs for bugs
- We can use age structure to predict population growth
(pyramids)
- Shape tells us something about the predictive
population growth
- Sharp on the left we would predict very rapid
growth
- High proportion go young people
- Less sharp on the right is still growth just slower
- Uniform would be no growth
- Upside down would be decline
- Demography: The study of the vital statistics of population and how they change over time
- Demographics include:
- Fecundity(Fx): Average number of offspring produced
by female aged x
- Survival Rate(Sx): Chance that individual aged x will
live to age x+1
- Can be years or minutes
- Survivorship(Lx): Proportion of individuals that
survive from birth to age x
- Nx: Number alive at age x
- Cohort: Group of individuals born during the same time period (same breeding season)
- Cohort Life Table: Follow a cohort from birth until
the last one has dies
- Done for non mobile organisms or stay in one
region year round
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- Static Life Table: Collect demographic information from individuals of different ages
- Used when starting age is easy
- When speeches are mobile or long lived
- Life raves are organized by age or life cycle stage
- Age for humans life cycle for things like bugs
- Example has age divided in 3 month periods
- 2 Would be 6 months later
- at 8 they all died
- Fx is how many offspring are produced
- In the static life table it looks at females in the
US
- Static cuz its long
- Humans like static life tables for stuff like
insurance because it shows how many years
you have left to live
- We can also look at proportions of individuals
within a population
- More people are going to uni!
- Education is increasing
- Survivorship curves come from life tables
- Plot of survivorship on the Y axis and
years on the X
- US dating is the green line up top
- Females have strong survival in the US
- Some countries are a lot lower
- Children die
- Gambia is low
- Illustrate a cohort affect
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- November and June have a higher
survival rate
- Has to do with nutrition (farming)
- K selected put a lot of energy in survival
of their offspring
- R selected dont put much energy in their
off spring at all (female spider laying
thousands of eggs)
- Post plants are type 3
- Type 2 is a constant chance
(predators, disease, resources)
- Curve can cary amount cohorts,
amount populations or between sexes
Chapter 12
- Hare populations increased and decreased regularly
- When hares were abundant, the Ojibwa had enough food to spend time trapping but..
- When hares were scarce tribal member concentrated on gathering food
- What causes hare rate to change?
- Food supply can be limiting at peak hare densities
- However some declining hare populations do not lack food
- The experimental addition of high quality food does not prevent population from declining
- Many hares are killed by predators
- Lynx and coyotes kill more hares at peak
- Predators does not explain why birth rates drop too
- Species interactions
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- Predation
- Parasitism
- Competition
- Mutualism and commensalism
- Eating grass is predation (being a herbivore)
(beaver eating a tree)
- Interactions between predators and preys are
trophic interaction (food level interactions)
- Most carnivores have broad diets
- Herbivores have relatively narrow diets
- 8.74 million eukaryote species on earth (not including bacteria or viruses)
- Huge amount of interactions
- Carnivory: Both predator and prey are animals
- Herbivory: Predator is animal and prey are plants or algae
- Parasitism: Predator (a parasite) lives symbolically on or in the prey (its host) and consumes
certain tissues
- Can live on surface or inside you
- Not all organisms fit neatly into these categories
- Some carnivores such as wolves also eat
berries
- Animals and plants need a wide range of nutrients
- May forge outside their typical categories
- Medicinal purposes to consume other things
- Wasp can inject eggs into a prey and the egg will develop there and eat the prey alive
Key Concept 1: Most carnivores have broad diets, where a majority of herbivores have
narrow diets
- There are exceptions for this rule
- Over all carnivores are generalist and herbivores are specialists
- Carnivores like the killer whale hunt a variety of prey
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- Optimal foraging and dietary preferences depend on:
- Encounter Rate: If low predators (carnivores) should be generalists
- Handling Time: If prey are easy to find but
hanging time is long… immobile but less
nutritious plants then predators (herbivores)
should be specialists
- Herbivores need to be specialists to overcome
the defence mechanisms of plants
- When they do overcome the defence the
results are devastating to the plants
- Leaf miners adults put its egg inside the leaves
and then inside the larva burrow around
consuming the plant material
- They specialize
- Majority of lead minors focus on few special of plants to attack
- Large herbivores specialize on particular parts of the plant
- Leaves are targeted because they are often abundant and the most nutrias part (except
seed)
- Animals have a high nitrogen content
- Then seeds
- Then leaves
- Most carnivores are generalists
- Dont hunt anything that comes across still have their certain prey
- Want to increase there profitability
- Minimize search and handling time
- Search image (knowing where prey hangs out) helps
- Sharks are piscivores (feeding on fish)
- Look for fish in shallow water
- Often carnivores concentrate on whatever prey is most abundant
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- Guppie example on right
- Respond to densities of prey
- Worm falls to bottom fish has to go down and grab the
worm
- Fruit flies lay on top of the water and fish peck the off the
surface
- 0 worms = 100% flies
- Green is 1 to 1
- S shape is between worm and flies
- 20 percentage prey are worms but 10% in diet
- More worms means switch to worms in diet when we expect more flies
- Graph is really saying carnivores are generalists but specialize on some preys to minimize
handling and search times to make food more profitable
- Hunting worms at a higher rate than they are present because they are being more
efficient because they learned to hunt better
Key Concept 2: Predation results in a wide range of capture and avoidance mechanisms
- Three hunting strategies
- 1. Many carnivores forage by moving about in search of prey (wolves, shark, hawks)
- Track prey
- 2. Others remain in one place and attack prey that come within striking distance (eels,
snakes)
- Strikes prey until they relax and they can swallow it alive
- Camouflage
- 3. Others set traps such as a spider web or carnivorous plants
- Size itself is an adaptation
- As is speed and armour
- Size is an ecological variation and changes with life history
- Can help prey escape predators
- Big sea lions can eat small sharks
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- How fast should you run?
- Some animals can run faster to escape prey
- But you need to minimize your efforts (run as fast as you need to escape your predator)
- Dont waste energy
- Evolutionary the prong head deer might have had more predators in the past so they are
really fast now
- Armour can be like the blow fish that blows up and extends its spines
- Porcupine move quills into the prey
- Its better not to be seen (camouflage)
- Animals can loose limbs or claws (automatization)
- Prey escape with their life
- You can also be poisonous
- You wanna be seen and send out a warning signal
- Aposematic colouration such as in monarch butterflies can be toxic from milkweeds
- You can make colouration to pretend that you are evil
- Worms take on the colour of
poisonous snakes
- Octopus take on colour of
snakes and imitate its
behaviour with its arms to
scare of predators
- Bees also have aposematic
colouration
- Other animals can mimic the
warning colours
- Batesian mimic and mullerian mimics
- Different colour signals been different things
- If they will sting or not
- Hoverfly mocks it
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- Also aposematic newts
- Aposematic means to warn
- Can be costly
- Newt takes on TTX neurotoxin,
send out bright yellow colouration
on tail to warn
- Snakes can still eat these newts
- Some snakes can detoxify the TTX
but slows down the snakes (the
cost they have to pay)
- Trade offs in defence
- All adaptations come with trade offs
- In snails for example the more
protective shells the slower you move (heavy)
- Short handling time (small shells easy to break) have a lot faster avoidance times (move
faster)
Key Concept 3: Predator populations can cycle with their
prey populations
- Lynx hair populations have cycles that are linked to one and
other
- Huffaker constructed a lab experiment
- Bulbs and oranges
- Oranges are food items for prey mites
- Also introduced a predator mite feeding on herbage mite
- Expected inspection (predator would kill all prey)
- Only got 1 cycle (increase in predator and prey and follow the same path)
- Wanted to create cycles with no extinction
- So he spaced out the oranges
- Got more cycles but eventually there was extinction
- Predator mites crawl and prey can parachute
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- Modified experiment
- Put vaseline down to prevent the free movement
across the orange space
- Increased disposal capabilities of prey mites that can
parachute
- Some prey can disperse to other oranges
- Then populations increased because they colonized
another orange
- Saw cycles between predators and prey (blue is
predator on bottom axis)
- Some populations are free of predator so the prey can increase and return the cycle
- Natural populations have similar dynamics as huffaker was studying
- Mussels can be driven to local extinction by sea stars
- Larvae disperse to new habitats
- Mussel has complex life history
- Larvae live in plantain and habitat will be recolonized
- Many factors can prevent predators from driving prey to extinction
- Habitat complexity and limited dispersal (as in Huffakers mites)
- Prey switching in predators
- Spatial refuges (where predators cannot hunt effectively)
- Evolutionary changes in prey populations
Key Concept 4: Predation can affect prey distribution and abundance in some cases
causing a shift from one community type to another
- Counting spiders on right
- Refers to extinct spider species %
- If lizards are absent there is less extinction
- Introduced lizards where there is no lizards
- What you find is a high rate of extinction (lizard has a big impact)
- When lizards are there naturally it does have an impact on species
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- Keystone Predators
- Muscles and starfish
- Some predators are a lot more important than others
- Starfish have an impact on the community as a whole
- There is a dynamic going around with predators and prey
- Geese eat grass but poop which the grass can use to grow
- Not so destructive as we thought
- When geese are low in abundance they add to the growth of the soil
- When the geese take over then it can be destructive
- Density of predator has an effect of the environment
- When we remove predators we see real changes in ecosystems
- We dont know what shift will happen will polar bears go extinct for example
Chapter 13
- Case study: Enslaver parasites
- Cricket drowns itself and worm leaves its body
- Larva feed on tissue
- Must return to water when fully grown
- Next generation is released to the water and must be injected by host to survive
- Observations show that when crickets infected with hair worms are near water, they are
much more likely to enter the water than uninfected crickets
- When rescued they would jump back in
- Enslaved by a fungus
- Shortly before they fie from infection yellow dung flies infected by the fungus move to the
downside of a tall plant and perch on the underside of a leaf
- This position increases the chance that fungal spores release and land on healthy dung
flues
- Macro parasite latches onto the outside
- Parasite doesn't have to kill the host
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- Host and symbiont (parasite)
- Cleaning stations in a coral reef can clean off the parasites
- Symbiont is different from symbiosis
- Symbiont live in close relationships and can for parasitic relationship
- Symbiosis 2 organisms can be closely associated but aren't living off each other (clownfish
lives in sea anemone
Key Concept 1: Parasites typically feed on only one or a few host species but host
species have multiple parasitic species
- Trees have a lot of parasites
- Multiple parasites within all groups
- We have micro parasites and macro parasites
- Headline are macro
- Headline specialize on a region in your body
- Head and body
- Different claws
- Thin hair is less likely for lice
- Crab and pubic lice are in the pubes
- They are macro (can see with the eye) and ecto parasites
(live outside)
- Trichophyton is a genus from Kingdom Fungi
- Tinea
- Athletes foot and jock itch
- Micro and ecto parasitic
- Sushi should be frozen at -40 to kill the worms
- Endoparasites live inside their host
- Scolex is the tape worm
- Suckers and hooks to attach to intestinal wall
- Hooks attach the lower intestine and hangs so the animal can continue to grow
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- Nematodes are a round worm
- Large
- Males are shorter with curly tale
- Female is larger and can produce millions fo eggs in
their life times
- These parasites allocate their energy
- Growth
- Survival
- Reproduction
- Penetrate us and minimize the energy needed for
survival (more protected within us)
- Microparasites: Microscopic such as bacteria
- Macroparasites: Large species such as arthropods
and worms
Key Concept 2: Hosts have mechanisms for defending themselves against parasites and
parasites have mechanisms for overcoming host defences
- The above sentence is co evolution
- Changes in gene frequency in the host and then the parasite counteracts with its own
changes is gene frequency
- Animals and plants have either a skin or epidermis
- Parasites need to penetrate or stick to this
- Chimps infected with nematodes seek out and eat a plant that contains chemicals that kill or
paralyze the nematodes
- Animals can eat leaves with hooks to help flush out the parasites
- We need to protect ourselves
- Immune system
- Biochemical
- Methods in plants to attack their pathogens
- Symbionts
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- Trillions of bacteria in our bodies that protect us from parasites
- Theobroma cacao (cacao tree)
- Pests include insects, viruses, mistletoe and fungi
- Spray with fungicide to kill fungus but also kills the midge fly responsible for fertilizing the
flower
- Some beneficial fungus protect it from bad fungus
- Protection by a bacterial symbiotic can be
against other parasites like fungus
- Symbiont present the organism does
better
- Anopheles is a bug that can bite us and
pass on parasites
- Not a parasite itself
- Passes Plasmodium falciparum which is
responsible for malaria
- Occurs in tropic area
- When a mosquito bites us it send a
cocktail into us to allow blood flow
- Also send in the parasite
- Sporosite is a dispersal stage of the
parasite
- Only takes 1 to get malaria
- Before it gets into the female mosquito as a
sporosite there are developing eggs that
came from the gametophyte of the parasite
(have sex)
- Have sex and the oocyte grows up develops
to a sporosite that travels to the salivary
gland of the mosquito
- Eukaryotic
- Sporosite go toward our liver
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- They also need a cocktail to get into our liver
- Once they get into a single liver cell they amplify themselves
(asexual) into merozoite
- Merozoite is more chubby and then leave liver cells to enter our
blood
- Merozoite's go back and now specialize to attack
our blood cells
- Set up camp in our blood cells
- Produces more merozoites asexually
- Grows exponentially
- What you see is a trophozoite which is the
feeding and growth stage
- Takes and consumes energy fo our blood cells
- Immune system wants to destroy it but the parasite
change the surface of our blood cells and group
together and hold on
- If you have malaria, once your blood vessels start to
die you get fever and chills
- Your body wants to kill these cells in the spleen
before infection takes place again
- Some of these merozoites become
gametocytes and go to the capillary beds at the
surface of our bodies and then the mosquito
can suck it back up and form more
- The anopheles lives longer as an individual and
has a wider spectrum of biting us so that could be
why the parasite infects them to infect us
- The tapeworm has a scolex and proglottis
- Each proglottis is like a colony, has there own
male and female parts that can have sex and be
fertilize and develop eggs and get larger as it goes
towards the tail
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- Become full of eggs
- Each single proglottis leaves in the poop goes into the soil and can potentially get
consumed by other organisms
- Good hygiene is a good way to protect ourselves
- What do we do about biting bug
- Kill the vector (mosquito)
- Change the sex ratio?
- Males dont drink blood so introduce more males
- Change our behaviour?
- Set up mosquito nets
- Bug spray
- Parasites can change the behaviour of their hosts to their advantage
Key Concept 3: Host and parasite populations can evolve
together, each in response to selection pressure imposed
by the other
- Evolution of ectoparasites coevolve with their host
- Example is lice
- We share the hair and skin lice with the chimps
- The nematode species we get is just to us
- European rabbit first introduced into Australia in 1788
- In 1950 ecologists estimated 600 million rabbits across the continent
- Destroyed natural landscape
- We hunt them too
- We poison and fence and trap them but other really helped
- Someone had the idea to take a virus and give it to the rabbit
- Kills the habit rapidly dropped from 600 to 100 million
- Coevolution: Rabbits more resistant, virus less lethal
- With time it became less virulent
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- Has to do with the mosquitos which transmit the virus
- If the rabbits die to fast mosquitos can suck up the virus
- Less virulent (live longer w the virus) become selected over time
Key Concept 4: Hosts and parasites can have important effects on each others
population
- Parasites can influence host population cycles
- Parasitic nematode can infect birds
- Adult (male or female) is the definitive host
- Infects digestive system
- Offspring of parasite (eggs) are laid and excreted in the poop
- Parasites can reduce their hosts geographic range
- Virus brought into rabbits to kill them off in Australia
- Invasive pathogens such as the chestnut blight is a parasitic fungus
- Hundred of years ago the chestnut tree dominated north America
- The fungus came from Asia and wiped out most of the chestnut tree population
- Parasites can increase their geographic range
- With changes in abiotic conditions such as our present climate emergency
- More humid and hot
- Increase in warming means some parasites are spreading faster such as skin sores from
leishmaniasis
- 2 million new cases each year
- Sand flies transfer the disease to our blood system
- Also have secondary hosts (resivouir hosts) such as rodents that hold the parasite if we
got rid of all the flies
- Movement of the vector and resivouir changes with climate change (increase)
- Lowering the density of susceptible individuals can control the spread of disease
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Key Concept 5: Parasites can alter the outcomes of
species interaction thereby causing communities
to change
- Corophium Volutator is a species of amphipod
crustacean
- Tiny
- Can occur in 100000/m^2
- Make tunnels and now many organisms can
survive within these holes
- Ecosystem engineers
- Coral symbiodinium are engineers
- Beavers are engineers
- Parasite (flatworm) infects and densities drop
- The flatworms make erosion and the island disappear
- Amphipod makes holes, flatworm lives in them and ruins environment which can cause
extinction of other species
- The starfish is a keystone predator the preys on mussels
- With the keystone species removed from the community we see a shift in alternative stable
states
- Wasting disease
Chapter 14
- Competition between species is interspecific competition
- Competition within a species is intraspecific competition
- We mostly focus on inter
- Species 1 is competing with all other species fighting for resource 1
and 2
- Called the realized niche
- If a species had its way it would not compete and spread out and get
both resources
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- Fundamental niche
- Fight for abiotic resources such as water, light, space
- Biotic resources such as food and mates
- Food can be intra or inter specific
Key Concept 1: Competition can be direct or indirect, vary in its intensity and occur
between similar or dissimilar species
- A) Species may compete directly or indirectly
- B) Competition can vary in intensity
- C) Competition is often asymmetrical
- D) Competition can occur between closely or
distantly related species
- Tide pools are good studying techniques
- Different species of sea anemones, green and
red species
- A) Species compete indirectly
- Larva they eat is in limited supply in a tide pool
- Anemones wanna eat it
- Exploit the food resource at a greater rate than the real ones
- A) Species compete directly
- Now imagine rocks in the tide pool
- Anemones can get up on the rocks to be in a better position
- Anemones fight for a better place on the rock to reach their food
- Interference competition
- Have stinging cells that can sting (pneumaticists)
- Jelly fish have the same pneumaticists that can sting us
- Inference competition in plants
- Competition for nutrients in the soil is exploitive competition
- Competing for light
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- B) Competition can vary in intensity
- Low food available more competition
- More food available less competition
- C) Competition is often asymmetrical
- One species is harmed more than the other and one species might drive the other to
extinction
- Higher population of 1
- Experiments with 2 diatom species by
Tilman in 1981
- Looked at diatoms which are single
celled organisms that have a glass
skeleton that requires silica
- Silica is a limited resource
- The green is the silicon content and
drops right away
- Organisms consumes it the produce its
skeleton
- When 2 species are put together the
silica disappears and one species
outcompetes the other and the other goes extinct
- D) Competition can occur between closely or distantly
related species
- Ants and rodents compete for seeds
- In direct competition with each other
- Eat similar size seeds
- In the same area and abundant each one gets less
seeds
- Can be distantly related but share the same
resource
- If your in competition theres a lot of organisms occupying there realized niche rather than
there fundamental niche
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Key Concept 2: Competing species are more likely to
coexist when they use resources in different ways
- In the 1930s G.F Gause did competition experiment
with Paramecium
- P. caudatum
- P. bursaria
- Grows them and measures the density in aquarium
- Initial exponential growth then levels off at carrying
capacity
- When put together things change
- Compete but dont drive each other to extinction
- One carrying capacity is larger than the other but
both dropped compared to when they were alone
- Take and add a new paramecium P. aurelia
- Also grows exponentially when alone at first
- Raise 2 together P. aurelia survives while other dies
- Lower density but eliminated the other species
- In the first example there was 2 species coexisting
- In the other one species drives the other to extinction
- When the coexist one species eats bacteria while the smaller one eats yeast cells, so the
specialize on a different food source
- The other example they both specialize on the same food so one drives the other to
extinction
- This is competitive exclusion principal
- One carrying capacity drops while the other goes extinct
- Given time can we actually change the relationship where one goes extinct?
- Character Displacement: Competition causes the phenotypes of computing species to
evolve to become different over time facilitating resource partitioning
- Different over time
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- Go back to Darwins finches
- Competitive coexistence by character displacement
- Many island
- Galapagos islands as a natural experiment in evolutionary ecology
- Looked at yellow and blue finch and character displacement hypothesis
- If yellow and blue finish landed on an island with identical beaks we would expect one
possibly driving the other to extinction because they are so similar in beak size but one
might be faster (this is a prediction)(this happens with time and NO evolutionary change,
one goes extinct)
- Carrying capacity goes down for both 100%
- With time and evolutionary change the beaks will
change so that they can hunt different types of
seeds and they aren't competing head to head
(shift in allele frequency)
- When the 2 separate THAT is character
displacement
- On the bottom of graph is size of prey (seed)
- Species 1 is red 2 is blue
- Peak is the mean
- After being together for some time the means
change, one is larger one is smaller
- Could directional selection explain the observation of change
beaks?
- Could disruptive?
- Observe more island? would this support the idea of
character displacement?
- Living on there own vs together
- When alone they are the same
- When together ones larger and ones smaller
- Looking at stickle back fish the same character displacement
existed
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Key Concept 3: The outcome of competition can be altered by the physical environment,
disturbance and predation
- In a series of classical experiment Joseph Connell
(1961)
- Realized niche is driven by competition and abiotic
factors
- Looking at steep slopes on rocky shores full of
organisms (barnacles, starfish, mussels,…)
- Might be under water for half the time
- Tide comes up and barnacles go under water
- Legs come out and lick around (filter feed)
- Benthic animal that filter feeds on organisms
- If you look closely at the rocks, one species occupies
each zone
- Realized they aren't only benthic
- Complex life history
- Benthic stage is the adult stage
- Gives rise to pelagic (planktonic) turn into Cyprid like a tadpole
- Cyprid finds a spot on the rock and swims out
- Barnacle has the largest penis
- When the cyprid finds a rock, its all over the rock
places everywhere
- Start to grow up and little competition for food
- Compete for space eventually (adults are so
packed)
- In the lower part of the tide Semibalanus pushes
out Chthamalus
- Chthamalus is better at withstanding desiccation
so you can find it higher on the shore
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- Take advantage of disturbances (fugitive species)
- Time is important
- If species that are that competitive take advantage
of disturbances
- If a log drifted in and crashes into the rocks killing
species theres now time and with speed to
species can go in and grow
- Competitions in chipmunks and plants too
Chapter 15
- Mutualism and commensalism
- Animals have a way of dealing with their parasites
- Cleaning stations
- Mutualistic relationship where little fish clean large fish mouths
- Benefit of the client has to be higher than the benefit of eating the fish
- Little fish aren't really a big meal
- Cleaner fish get a lot of benefit
- In the forest theres also a similar relationship
- Even on our skin theres communities
- Mites in the pores
- 1. In positive interactions neither species is harmed, and the benefits are greater than the
costs for at least one species
- 2. Each partner in a mutualistic interaction acts in ways that serve its own ecological and
evolutionary interests
- 3. Positive interactions affect the abundances and distributions of populations as as well as
the structure of ecological communities
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Key Concept 1: In positive interactions neither species is harmed, and the benefits are
greater than the costs for at least one species
- Mutualism: Mutually beneficial interaction between individuals of two species (+/+
relationship)
- Commensalism: Individuals of one species benefit; individual of the other species does not
but they are not harmed (+/0)
- Symbiosis: Two species live in close physical contact with each other
- Symbiosis can include parasitism (+/-) commensalism and mutualism
A) Mutualism and commensalism are very common and found everywhere
- Millions of species form +/0 relationships with organisms that provide habitat
- Oceans and forests
- Kelp forests harbour a lot of species
- Birds eat bugs off elephants
- Fish stick to sharks and eat its scraps
- Barnacles on whales
- Commensalism can be turned to mutualism
- Mutualism is like birds getting good from a flower and pollinating it
- Habitat mutualism share habitats
- Ectomycorrhizae fungus is plants extend roots in exchange for CO2
- Herbivores depend on bacteria and protists that live in their gut to help metabolize cellulose
- Eating wood or lots of plants
B) Positive interactions can be obligate or facultative and loosely structured
- Obligate mutualism
- In an obligate partnership each cannot survive without the other and both have evolved
unique features that benefit the other species
- The fungal garden of a leak cutter ant
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C) Positive interactions can cease to be beneficial under some circumstances
- Millions of species form +/0 relationships with organisms that provide habitat
- We can have a shift in these relationships
- Too many sea urchins living in a kelp forest will eat and destroy it
- Urchin barrands
- +/- relationship
- Mite in our pores die we can get red blisters in our face
- Barnacles and lice on whales that slow it down or eat its flesh
- Small flower forget-me-not
- Crowns with cattail
- Flowers are smaller when grown without the cattail because theres less air in the soil
- Especially when its cold
Key Concept 2: Each partner in a mutualistic interaction acts in ways that serve its own
ecological and evolutionary interests
- Mutualists are in it for themselves
- Mutual benificial interactions between individuals of two species is +/+
- Bugs feed off plant and squeeze out honey dew
- Ants protect aphids against predators in return for sap
- If no predators around ants are still there
- Plant roots know who's benefiting them and can decide who to give more plant sugar
- Are there cheaters?
- Yaka plants pollinators are yaka moths
- Can carry huge ball of pollen
- Deposits eggs in the flower and the pollen at the same time
- Larva eats the plant seeds as a reward
- Plant can recognize if theres too many eggs then can kill the flower off killing moth babies
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Key Concept 3: Positive interactions affect the abundances and disturbances of
populations as well as the surface off ecological communities
- Very ecologically important
- Huge part of fish depend on coral reefs
- Cleaner relationships if you take the cleaner away there are more parasites really fast
- Over a period of a year the number of species of fish went down as well as the number of
fish within a species
- Tropical water is like deserts
- Clear blue means less algae which means less energy
- Corals provide energy
- Each poollup is a relationship
- Symbiodinium: An endosymbiotic dinoflagellate which is an intercellular symbiont
- The coral provides the alga with a home, nutrients (nitrogen and phosphorus) and access
to sunlight
- The alpha provides the coral with carbs produced by photosynthesis
- Indirect assistance with deposition of their calcium carbonate skeletons
- Coral reefs harbour an immense biodiversity
- Global distribution of corals is correlated with temperature
- Climate change is killing it
- We are conducting an experiment driving our cars, buying stuff, heating and cooling our
homes adding carbon to the atmosphere killing coral reefs
- Corals require a stable temperature with a narrow range to live
- Corals go white because symbiodinium die
- Increasing temperatures and UV radiation is uncoupling the mutualistic relation
- Possible that the symbiodinium produce Superoxide O2 and stresses the coral until the
coral expels them all
- Small change in global temperature can have rapid and dramatic impacts on ecosystems
- Storms also kill it
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Chapter 16
- 1. Communities are groups of interacting species that occur together at the same time and
place
- The term ‘community’ can be used in many contexts
- People often refer to themselves as belonging to a rural community or an urban community
- You also belong to the university community
- In ecology, the term ‘community’ is similarly flexible, but an ecological community always
contains multiple species that interact with one another
a) Defining The Boundaries of a Community
- An ecological community can be associated with a physical entity such as a river, lake,
desert, mountain or hot spring
- It might also be a biological entity such as a forest, coral reef or meadow
b) Defining The Members of a Community — All or a Subset?
- i) Taxonomic Affinity
- In theory, a community includes all the species within its boundaries
- In practice, it is impossible to know the complete list of species within most communities
- Not only are many species within a community microscopic (e.g., bacteria) but many have
yet to be discovered and identified
- Most often, ecologists study a subset of species within the larger community
- There are three common types of subsets, the first being taxonomic
- For example, an ecologist might study a butterfly community or a bird community
- ii) Guild: Group of Species That Use Similar Resources
- The second type of subset is a guild: a group of species that use similar resources
- Animal guilds tend to be grouped based on their diet, such as insectivores, frugivores (fruit
eaters), nectivores, etc.
- Plant guilds tend to be grouped based on their growth form such as forbs, succulents,
conifers, etc.
- i.e. Can be grouped by animals that feed on nectar or pollen or plants with a similar growth
form
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- iii) Functional Group: Their ‘Role’ in the Community
- The third type of subset is a functional group
- Members of the same functional group perform the same role (or function) within the
community, such the decomposers or the nitrogen-fixers
- Functional groups may also be defined in terms of energy flow within the community
c) Categorizing Members of a Community
- i) Trophic Levels
- The relationships among species in terms of energy flow are typically depicted in a trophic
pyramid
- The producers (also known as primary producers) fix solar or chemical energy into carbonbased molecules
- This energy is the pool of energy available to the producers as well as other members of
the community
- The shape of the pyramid reflects two things: the relative biomass of individuals within the
community and the relative energy contained within each trophic level
- The first trophic level (the producers) form
the base of the pyramid
- The next trophic level contains the primary
consumers, which are the animals that eat
the producers (the herbivores)
- The next trophic level contains the
secondary consumers: the predators that
eat the herbivores
- The tertiary consumers eat the secondary
consumers, and the quaternary consumers
eat the tertiary consumers
- Each of the secondary through quaternary consumers are carnivores; the pyramid places
them in a hierarchy based on the type of prey that they eat
- There are rarely more than four trophic levels in a community
- This is because there is rarely enough energy to support higher levels
- To understand this, look at the values for the energy pyramid (on left side of the trophic
pyramid)
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- At each level, 90% of the energy intake is used by the organisms for metabolism, growth,
reproduction or is radiated as heat
- This leaves only 10% of the energy within a trophic level that can be transferred to
consumers at the next trophic level
- Dividing species into trophic levels is helpful but some types of species are difficult to
categorize in this way
- Omnivores eat organisms form any other trophic level, which makes them simultaneously
primary secondary, tertiary and/or quaternary consumers
- Corals are both secondary consumers (they eat zooplankton) and producers (they contain
algae)
- Some organisms occupy different trophic levels at different lifecycle stages; the young may
be herbivores and the adults may be carnivores(frogs)
- Decomposers feed on dead organisms from all trophic
levels
- ii) Food Web
- One way to overcome the problem of species types
that don’t fit nicely into a single trophic level is to
construct a food web
- A food web incorporates information about trophic level
and allows one to show variations in the flow of energy
- In this example, the flow of energy is shown by the blue
arrows
- A food web shows individual species (e.g., producer1,
herbivore2, etc.) as well as who eats whom
- In this case, the omnivore C1 (secondary consumer1) is shown to consume both plants
(producer1) and animals (herbivore1)
- As you might imagine, the food web within a community can become very complex
- However, it nicely illustrates how one can include different life stages (larvae, tadpole
versus adult) within the web, as well as species that eat each other depending on relative
sizes of the individuals
- For example, large dragonfly larvae can eat small salamander larvae and vice versa
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- iii) Interaction Web
- Both trophic pyramids and food webs
contain information about energy flow
but neither includes information about
other types of species’ interactions
within a community
- An interaction web incorporates
information about both trophic and nontrophic interactions
- In this example, the trophic interactions
are indicated by blue arrows, and the
non-trophic interactions are indicated by
red arrows
- Bolus is baby bird vomit (albatross)
- Casting = vomiting up a bolus
- Babies wanna be as light as they can
- Birds vomit squids and squid beaks
- Plastic is also found
- Humans are generalists feeding on a bunch of species
- Omnivorous
2. Species Diversity and Species Composition Are Important Descriptors of Community
Structure
- a) Quantifying species diversity
- Species Richness: The total number of species in the community
- Species Evenness: Takes into account the relative abundance of each species in the
community (higher evens means more equal
representation among species)
- Dominated by one species means low evenness
- Species Diversity: A measure that combines the
number of species and their relative abundance in
the community
- Both richness and evenness
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- Shannon Index is used to calculate
diversity within a community
- Dont have to memorize
- Negative
- ln Is the natural log
- Biodiversity: The diversity of important
biological entities that span multiple scales
- Alleles
- Genes
- Species
- Communities
- Not the same as diversity
- Applies to an entire
ecosystem with many
communities will diversity is
one community
- Assessing species evens —
Rank abundance curve
- Within a community
- Decreasing relative
abundance
- 1 means most abundant
- Abundance number 2 is the next abundant and so on
- The steamer the line the lower the evenness the latter the higher the evenness
- Richness is how wide (abundance rank)
- Estimating Species Diversity
- Species area curve/species
accumulation curve
- As more are counted the curve flattens
off
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- Species Composition
- Two communities could have the same species richness (s) and the same species
diversity (H) but the actual special and types of communities could be very different
- For example tropical island vs human digestive tract
3. Communities Can be Characterized
by Complex Networks of Direct and
Indirect interactions That Vary in
Strength and Direction
- Direct is solid blue
- Indirect is dashed
- If a is a parasite and B is a herbivore that is direct
- Indirect is if plant is C
- Parasite has direct on herbivores and herbivore is direct on plant so the more parasites,
the less herbivores so more plants
a) Indirect Species Interactions Can Have Large Effects
- i) Trophic Cascade: The rate of consumption at one trophic level results in a change in
species abundance at a lower trophic level
- Sea-otters eat urchins so if more sea otters eat urchins then more kelp is alive because
urchins eat kelp
- ii) Trophic Facilitation: a consumer is indirectly helped by a positive interaction between its
prey and another species
- Aphids feed of shrub so more shrubs there are the more aphids there will be (+ direct
interaction)
- Presence of the Rush benefits the shrub and the presence of the shrub and no effect on
the rush
- Because of the + interaction the more rushes mean more shrubs mean more aphids so +
indirect interaction
- Rush and shrub are competitors fro space and nutrients but the rush provides shade to
decrease salinization of substrate
- Rush provides oxygen to the substrate
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- iii) Competitive Networks:
Competitive interactions smoking
multiple (at least 3) species in which
every species has a negative effect on
every other species
- Networks aren't linear compared to
hierarchy's
- Similar to rock paper scissors
- No one competitor always wins
- Having more competitors reduces the ability of any one competitor to dominate the
community
b) Species interactions vary in strength and direction
- Interaction Strength: The effect one species has on the abundance of other species
- Remove the interaction species and observe effects of target species (move rush observe
aphid)
- Estimate the interaction strength (large/strong vs small weak) and direction (positive,
negative or neutral) for 2 scenarios
- Rush is the interaction and target species is the aphid
- Fewer aphids (strong - )
- Aphid is the interaction and rush is the target
- Weak because interaction is 0 (neutral interaction)
- Keystone Species: Large effects despite low abundance
- Foundation Species: Large effects due to large size or high abundance
- Redundant Species: Small or negligible effects on the community
- Ecosystem Engineers: Create, modify, maintain or destroy a physical habitat. This may
affect themselves and other species, Can be foundation or keystone
- Beavers
- Beaver damns slow down water and nutrients and create new habitats important to other
animals
- New sediments by raising water tables and flooding valley bottom
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- Provide water source for farmers
- Elephants eat a lot of food
- Poop a lot
- Ecosystem engineers because poop is good fertilizer for growing seeds in the ecosystems
- Plants can grow better when passed through elephant digestive tract
- Wolves killed and changed behaviour of deer to avoid places of yellow stone park so those
places regrew a lot and created forests and the birds came back and beavers came and
created dams to provide habitats for many other species
- Changed rivers, less erosion, more pools, etc
- Regenerating forests stabilized the balance
Chapter 17
1. Agents of Change Act on Communities Across All Temporal and Spatial Scales
- i.e. Changes caused by glaciation or climate change (long term and short term)
- Some changes can be very fast like when a fire has a forest
a) Agents of Change Can be Abiotic or Biotic
- i) Abiotic agents of change
- From longest to shortest:
- Increases in sea level
- Warmer temperatures
- Pollution
- Reduced light availability
- Fires
- Floods
- Wind/rain/snow storms
- Volcanic activity
- Duration of effect is not proportional to the time it took to cause the change
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- ii) Biotic agents of change
- From longest to shortest:
- Competition
- Mutualism/symbiosis
- Predation/herbivory
- Foundation species
- Keystone species
- Disease/parasitism
- Digging/burrowing
- Trampling
- iii) Interactions among abiotic and biotic agents
- Ecosystem engineers (beaver)
- Beaver dam causes abiotisc changes that cause biotic changes
- Stressful environments (eel river in
California)
- On the left of the image there are 4
trophic levels
- Arrow thickness is proportional to the
amount of energy flowing through the
levels
- In the winter most of the algae is
eaten by midges so theres a lot of
energy in the community to support
each level
- With a drought in the winter the community changes so that more insect lard eat the
algae
- Midges are DROUGH SENSITIVE so the other species suffer and only 2 trophic lives
are supported
- Two categories of abiotic and biotic agents
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- Disturbance: An event that directly physically injures or kills some individuals and
creates opportunities for there individuals (can be abbots like fire or biotic like logging or
grazing)
- Stress: A factor that reduces the rate of an important physiological process, thereby
reducing growth, reproductive survival to some individuals (no one dies right away)(can
be abiotic light drought or biotic like diseases)
b) Agents of Changes Vary In Their Intensity, Frequency and
Extent
- Intensity (Severity): Is proportional to the amount of damage or
death caused
- On the graph combo with extent
- No organisms can survive frequent high intensity agents of
change
- Frequency: Is a measure of how often the agents of change
has an effect
- Extent: Is proportional to the area of land or number of
individuals affected
2. Succession is The Process of Change in
Species Composition Over Time as a Result pf
Abiotic and Biotic Agents of Change
- Nature will take over if an area is undisturbed
- Succession involves a series of colonizations
and extinctions driven by agents of change
- Theory was developed first for the plants but
works for animals
- Succession of insects is applicable to
forensic entomology
- On a corpse
- Flies the beetles
- Gives timeline of when body entered the
environment
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- Succession is unidirectional (simpler yo more
complex communities)
- Disturbance and stress send the community back
to an earlier stage
- High intensity disturbance to get species
replacement
- Succession starts with no life (volcanic eruption)
- As things change we enter the pioneer stage
- The intermediate stage and climax stage (stable climax community)
- Agents of change can set them back
a) Primary Succession
- Time on the x axis
- Starts with bare rock
- Pioneer species are the first species to populate
and need to be stress tolerant
- As pioneer species establish the change the
environment (decomposition builds the soil which helps water retention and better soil with
more nutrients)
- Then goes intermediate species and so on
- Physical changes take a long time (hundred of
years)
b) Secondary succession
- Happens after moderate disturbance
- Shorter time rather than decades
- Only happens when the soil is not
disturbed
- Can happen from fire
- Deep soil organisms are unaffected and bird will survive
- Pattern is the same just happens faster because the soil is there
- Large disturbance sets us back to primary succession
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c) Four Important Community Ecologists
- i) Cowles: Space for time substitution
- Worked on sand dunes and noticed
that new sands were being
deposited on old ones
- Plants at the edge are pioneer
plants and the further back is an
intermediate or climax
- Primary succession cannot be seen over a human life time
- ii) Clements: A community is a
superorganism
- Thought that the species in a community
worked together
- The ones that coexist during first
succession are distinct in each area
- Sharp boundaries
- Early pioneer was an embryo, late was a larva, intermediate was juvenile and climax was
adult
- iii) Gleason: A community is a collection of
individuals
- Disagreed with Clements
- Independent species with their own limits
that cannot match others
- Predicts that each community is unique
and bless with neighbouring ones
- The truth is primary somewhere in the middle
- iv) Elton: Organisms and the environment
interact to determine the direction of
succession
- Over time the communities that developed
differed depending on the local soil
moisture
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- Damp was wet lands then scrub lands
- Damp then had mixed but wet was bogs then scrublands then pine
- Mixed had birch and pine
d) Three Models of Succession
- Facilitation
- Tolerance
- Inhibition
- Experimental evidence
supports each model
depending on the specific
community and the type of
experiment performed
- i) Evidence for facilitation
- Facilitation: One species modifies the environment in some way
that benefits other species
- As succession proceeds moisture and nitrogen increases which
supports further species
- Facilitation can also increase species richness, which increases
opportunities for symbiosis and formation of competitive
networks
- This can lead to increased climax community stability
- As richness increases so does diversity
- Facilitation is very important in early succession and can
be important late in succession if it increases physical
habitat structure (more niches)
- ii) Evidence for inhibition
- Inhibition: One species prevents other species from
establishing
- For example build up of dead and decomposing plant matter (thatch) that prevents
germination of other plant species
- Poking holes in the ground breaks the thatch layer
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- That is initially good for grass
- Keep the soil cool (reduces solar radiation)
- Slows evaporation from the soil
- Insulates the roots in the winter
- Reduces damage due to trampling
- Thatch can get to thick so the grass dies off and
decomposes so succession occurs
- Wild fires through grassland can also burn the thatch
and the earlier pioneer species can be established
- iii) Evidence for mixed positive and negative interactions
- Under low salt stress Distichlis does better if Juncus
(competitor) is removed
- Under high salt stress Juncus does better with Distichlis
(facilitator)
3. Communities Can Follow Different Successional Paths and
Display Alternative States
- A stable community returns to its original composition after a disturbance
- If the disturbance is a small area the regeneration comes from places around
it to fill in the space
- Stability depends on the scale (spatial and temporal) of sampling
- Re-grown can be more oak than pine 150 years later
- Alternative Stable States: Different
communities develop in the same area under
similar environmental conditions
- Alternative stable state theory shows a
landscape that can hold 2 communities (a and
B)
- One in the low dip one in the higher dip
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Chapter 18
- Patterns of species diversity and distribution vary at global, regional and local spatial scales
- Biogeography: The study of variation in species composition and diversity among
geographic locations
- Ubiquitous: Found everywhere
- Rat found everywhere
- Endemic: Occurs only in one region
- Kangaroos only in Australia
- Species richness and diversity is highest near
the equator
- Varies from continent to continent even at
similar altitudes
- White is 0
- Same community type can vary in species richness and composition depending where it is
on earth
- Alpine is Sweden and Canada are
different
a) Patterns of species diversity at different
spatial scales are interconnected
- Global Scale: Latitude, continental drift,
climatic regions, evolutionary time scale
- Regional Scale: Dispersal limitations, rates of
speciation and extinction
- Gamma is measure of richness
- Landscape Scale: Physical geography, emigration,
immigration
- Beta
- Local Scale: Physical conditions , species interactions
(community)
- Alpha diversity
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- Larger scale (global) sets the conditions for the next
larger scale
- Each above is what diversity is controlled by
- Gamma diversity is diversity of a region
- Alpha is the diversity of the community
- Beta is between communities
b) Local and Regional Processes Interact tp
Determine Local Species Diversity
- Regional (gamma) diversity is the maximum
available species richness for each of the local
communities
- To what extent is a local (alpha) diversity determined by
regional (gamma) diversity?
- Create a plot (regional richness vs local richness
- Curve is not proportional
- Spatial scale of sampling matters
2. Global Patterns of Species Diversity and Composition Are Influenced by Geographic
Area and Isolation as Well as Evolutionary History and Global Climate
- Wallace is the father of modern biogeography
- While he sailed around the globe in the late 1800s, he noticed that the mammals of the
Philippines looked more like the mammals of Africa than those of New Guinea
- But Africa was much further away, at least relative to New Guinea
- He set out to explain why
- Wallaces Line
- Careful studies on the islands in the region lead him to the conclusion that a line could be
drawn that separates the two types of mammalian communities
- This line has come to be known as the Wallace line (or Wallace’s line), which separates
distinctly different mammalian communities
- There is a deep-ocean trench underneath the line, which is a clue to why the mammals on
either side of the line are so different
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a) The Biotas of Biogeographic Regions Reflect Evolutionary Isolation
- After extensive explorations, Wallace concluded that Earths’ land masses can be divided into
six biogeographic regions
- Prior to his time, scientists thought that the continents floated on the ocean
- Due in large part to Wallace’s studies, the theory of continental drift was formulated
- We now know that large plates of surface crust move on top of, and apart from, one another
(plate tectonics)
- You can see that Wallace’s line lies right on top of the area
where the Australasian plate moved towards Oriental plate
- The mammals in the two regions had evolved before
those two land masses were close to each other
- Many of the species distributions that we see today reflect
past geographical positions of the continents, especially
for those species with short dispersal distances
- In addition to dispersal ability, the time at which a
species evolved also matters
- For example, if a new species evolved on Laurasia
after Laurasia and Gondwona split apart, then its
descendants will be more likely to be confined to the
set of continents that arose from Laurasia
- This figure shows the direction and timing of tectonic
plate movement
- Black arrows show movements of continental masses away from one another
- Red arrows show movement of continental masses towards one another
- The numbers indicate how many millions of years it took for the current position to be
- established. Thinking back to Wallace’s line, the Indonesian islands have only recently
(evolutionarily speaking) come together, which explains the differences in their mammals and
other life forms
- In addition, the area contains only islands, which means dispersal of mammals (other than
bats) has been limited
- Compare this to the merger of North and South America. Although less time has passed, the
mammals could easily disperse over land from one continent to the other
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- Modern patterns of biogeography are a result of all continents being together in the past
- Two main factors that explain global biogeography
- (1) Past geography: the relative positions of the continental plates and
- (2) Phylogeny: the evolutionary relationships among groups of organisms. Some
example organisms are shown on this slide
- The shaded areas show their distribution on the original land mass
- Their ancestors can be expected to be distributed on the corresponding regions of the current
continents
- One new term to know is vicariance: geographic
separation of a population by the formation of a barrier
- The vicariance of ancestral species on this slide arose from
continental drift, but the creation of other barriers can also
separate a population into two or more subpopulations
(e.g., mountain range, river, islands, ocean)
- These barriers usually arise over geological time
b) Species diversity varies with latitude
- In concept 1 within this chapter, I showed this slide and mentioned the general pattern that
species diversity increases with latitude
- There are two common exceptions to this
rule
- The first is a biodiversity hot spot,
which is defined as a region with higher
species richness/diversity than is
expected given its latitude
- Five such hot spots are shown on this
figure
- Not all taxonomic groups decrease in
species richness with increasing latitude
- The second exception to the general pattern is found in certain taxonomic groups
- For example, the number of species of seabirds is lowest in the tropics, and higher in the
northern and southern polar and temperate regions
- This same pattern is seen for marine benthic invertebrates
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- Possible reasons for this deviation from the typical pattern will be presented in a few slides
- Before we get there, let’s examine some factors that explain latitudinal gradients
c) Latitudinal Gradients Have Multiple Causes
- i) Greater land area in tropics
- The first factor is related to land area
- This figure shows the land area found in each of nine regions
- From left to right, these represent moving from the south pole towards the north pole
- Due to the current position of the continents, the land mass south of the equator is
relatively small
- The continental land mass in the tropical
region is the highest and, while land area
in the northern hemisphere is about three
times larger than the land area in the
southern hemisphere, it is only one third
the area of the land in the tropics
- Based on land area alone, one would
expect to find more species in the tropical
regions
- ii) Warmer, and seasonally stable, temperature in tropics
- In tropical regions, the temperature is constant year-round
- Closer to the poles, the winter temperatures can be 30-60 degrees colder than summer
temperatures
- Few species can tolerate these extreme shifts in temperature
- The graph on the left side of the slide shows the average annual temperature from the
equator to the poles
- Not only is the tropical climate more stable, it is much warmer
- iii) Tropics appear to be both a ‘cradle’
and ‘museum’ for speciation
- Look at the graph on the left side of
this slide
- Historically, more species originated
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(evolved) in the tropics (hence it being called a ‘cradle’)
- The graph on the right side shows that a high number of marine bivalves that currently live
in temperate zones are descendants of species that originated in the tropics and spread
towards the poles
- Not all the species shown in the right-side graph abandoned the tropics; some are also still
found there
- Either way, ancestors or conspecifics of temperate species still live in the tropics (hence it
being called a ‘museum’ – they are still there on display)
- Species tend to persist in the tropics because the rate of extinction is lower in the tropics
(data not shown)
- iv) Tropics have higher NPP (solar
energy captured in plant biomass)
- The more energy stored in plant
biomass, the more energy can flow
through the food web, which leads to
supporting more trophic levels
(hence, more diversity)
- This map shows the distribution of
net primary productivity (plant
biomass) across the globe
- Based on this distribution, one would
expect the highest species diversity in the tropical regions
- Marine NPP is highest as the poles (and the few areas of upwelling)
- So, how can one explain the higher diversity of seabirds and marine benthic
invertebrates in the polar regions?
- Look at the distribution of net primary productivity in the marine environment
- In this image, blue and purple represent low productivity in the ocean while green and
yellow represent higher productivity
- In the marine environment, the highest productivity is near the polar regions
- This pattern might help to explain why sea bird and marine benthic organisms are less
diverse as one moves towards the equator
- There is more trophic energy in the northern marine environment that there is in the
tropical marine environment
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3. Regional Differences in Species Diversity Are Influenced by Area and Distance, Which
Determine the Balance Between Immigration and Extinction Rates
a) Species richness increases
with area and decreases with
distance
- i) Species-area curves for islands
and island like habitats
- Communities separated by a
barrier by dispersal
- Species richness increase with
community area
- Makes sense, the larger the community,
more habitat types, more niches
- Steeper slope, greater difference of
richness among areas sample
- ii) Distance between an island and the main land also
affects species richness
- Look at different colours
- Near islands have higher species richness than
far islands
- Bigger communities have higher richness and the
distance between communities matters
- The closer the community is to a source of new species the higher the richness
b) Species richness is a balance between immigration an local extinction
- i) MacArthur and Wilsons Equilibrium theory of island biogeography
- Know this
- Foundation of conservation biology
- Imagine a new island formed by a volcano
- Primary and secondary succession need to happen first
- Rate of arrival of new species will be high at first with wind blowing seeds
and stuff
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- As island starts to fill up rate of arrival of new species slows
down but as time goes on rate of extinction increases because of
competition, predation and disease
- S = Predicted (theoretical) species richness when the island
community reaches an equilibrium
- Islands nearer to main land have higher immigration
- Smallest richness is on a small far island
- Largest is on a large near island
- ii) Mangrove island experiment in the Florida Keys
- Fumigated island to kill everything
- Waited a year and recounted everything
- iii) Theories of island biogeography applies on main land
- Extinction is higher on islands
- New individuals can easily migrate on mainland
Chapter 19
1. Species Diversity Differs Among Communities as a Consequence of Regional
Species Pools, abiotic Conditions and Species Interactions
- Recall from Chapter 18, each community within a region will have a different collection of
speciess
- The members of a community will be a (probably unique) subset of the regional collection of
species
- One can see many communities within the region shown in this photograph: montane, forest,
meadow, river, etc.
- Especially in the terrestrial environment, a few species may be found within more than one
community type but each community has a distinct set of species
- This is another way to represent the relationship between the regional and local species
groupings
- The regional species pool (the species richness of the entire region) passes through a set of
‘filters’ to determine which species will be within each local community
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- The first filter is related to mobility
- Species that have greater dispersal
(disperse greater distances) are more
likely to appear in more of the regional
communities
- If the environmental conditions of a
community are unsuitable for certain
species, they may arrive in the
community but not establish a population
- This is represented by the ‘abiotic filter’
in the diagram
- Species that are dependent on other
species in the community, or do not
experience competitive exclusion, will establish in the community
- This concept is illustrated by the ‘biotic filter’
a) Species Supply
- The local (community) species richness can be directly proportional to the regional species
richness
- In these types of communities, dispersal is the primary factor that determines which species
will be in a community
- The situation in which dispersal is the primary factor for community composition holds true
only if there are no (or minimal) biotic or abiotic filters
- The best examples of this situation are seen with invasive species
- To be considered invasive, an introduced species needs to become established in its new
environment and it must have a large effect on the native community
- Humans are a vector for dispersal of invasive species
- Humans have been responsible for the introductions of many invasive species
- One common situation is the world-wide spread of aquatic species in the ballast water of
ships
- Ballast water is taken in at one port to balance and stabilize the ship
- More water is taken up if the ship is carrying a light load; the weight keeps the vessel at the
right depth as it travels
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- Even more water is taken up for stability in stormy weather
- Ballast water is discharged when the ship takes on a heavy load
- Prior to early 1900s, most ships carried solid ballast (e.g., rocks or sand)
- Not surprisingly, when shippers switched to water as ballast, invasive aquatic species
became an increasing problem
- Today, an estimated 10,000 species are carried in ballast water each day world-wide
- In the 1980s it was about 3,000 species per day
- The difference in the past 40 years is due to having larger ships that travel faster, more of
these hitchhikers survive the trip to a new port
- Two of the best-documented invasive species that arrived in ballast water are zebra
mussels in the Great Lakes and the comb jellyfish in the Black Sea
b) Environmental Conditions
- Not all organisms that disperse to a new environment will establish a population
- As we saw in Chapters 4 and 9, physiological constraints limit the ability of organisms to
survive outside their preferred abiotic environmental conditions
- This explains why the vast majority of species in ship’s ballast water do not survive after they
are released into the new port
- Examples of abiotic limitation from the terrestrial ecosystem include the creosote bush and
saguaro cactus which are limited along the white dashed line above which where
temperatures can fall below 0 Celsius for more than 36 hours at a time, and aspen trees,
which are limited at various edges of their range by temperature to the north and drought to
the south
- Biotic Resistance: Interactions between native and non-native species that prevent the nonnative species from establishing in a community
- Species interactions at the local (community) scale can facilitate establishment of
complimentary species and prevent the establishment of other species, a phenomenon
called biotic resistance
- Evidence for this comes from studies on whether or not a non-native species becomes an
invasive species
- This is an example of two non-native grass species that were prevented from becoming
invasive
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- Two native granivores (seed eaters) consume a sufficient number of seeds of each grass
to keep the non-natives from establishing large populations in the community
- Native Herbivore: Lucerne seed web moth
- Invasive Plant: Grose (shrub)
- Biotic resistance is not always strong enough to prevent a non-native species from
becoming an invasive species
- This example comes from Australia
- Although the native lucerne seed web moth typically breed and feed on lucerne (celled
alfalfa in North America), it is able to breed and feed on nonnative gorse (the yellow shrub)
- However, gorse continues to spread and is out-competing some native plant species
- To control invasive species:
- Prevention: clean boats
- Not release exotic pets
- Plant gardens with native species
2. Resource Partitioning is Theorized to Reduce Competition and Increase Species Diversity
a) Resource (niche) Partitioning: Natural
selection competing species to use a limited
resource in different ways
- Sharing reduces competition and increases
diversity within a community
- Function of natural selection
- On the left is niche for species 1 (like food)
- On the right is how they share (realized niche)
i)
Resource Partitioning Can Increase Species
Richness
- In the top graph you see that each species
has an optimum value for each resource with
lots of overlap which leads to competition
- In the bottom you see more specialization
with less competition
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ii) Experimental Evidence for Resource
Partitioning
- MacArthurs Warblers
- Bird communities is US
- Dont have to know species name but
know the concept
- Each bird feed on same insect but
partitioned it as a resource
- Shows what regions of the tree each species feeds on the
insect
- Little overlap and reduced competition
- Bird diversity was not proportional to plant species diversity
- Bird diversity was proportional to the structural complexity of
the habitat (foliage hight)
3. Processes Such as Disturbance, Stress, Predation and Positive
Interactions Can Mediate Resource availability Thus Promote
Species Diversity
a) Paradox of the Plankton: How can so many species
coexist
- Environment (limnetic, photic zone) structurally simple
- Shared resources (light, CO2, nutrients)
- Waves and wind distribute resources
- Resources are limited
- tc ( time for competitive exclusion) and te (time for
environmental variation)
- One species winds or both species decrease and
increase in cycles
- Species one grows faster after disturbance in
second graph
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- If tc<<te competitive exclusion occurs before conditions
change
- Same result as in a stable environment
- Happens before the environment changes
- If tc>>te and if long lived competitors are adapted to
abiotic fluctuations then competitive exclusion will occur
- Both species are temporarily knocked down
- Both can recover but blue recovers faster
- Over time species b will die out
- If tc=te competitive exclusion will not occur
- Example: Mussels do not outcompete barnacles in the
presence of the sea star but muscles do outcompete
barnacles in the absence of the sea star
b) intermediate disturbance hypothesis
- Highest species diversity is at intermediate levels of
disturbance, stress or predation
- When levels of disturbance are low diversity is reduced by
competitive exclusion and then look on the graph for high
c) Lottery Model
- Chance plays an important role in species diversity
4. Species Diversity Affects Community Function
- Community Functions: Abiotic and biotic processes that control community structure
- Species diversity increases:
- Plant productivity
- Water quality and availability
- Atmospheric gas exchange
- Resistance to disturbance or invasion (inc. biotic resistance)
- Disease suppression
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- Example: Hantavirus
- Carries by deer mice but don’t
experience disease (we do)
- By trapping non host mammals
diversity was lowered which increased
host in the community
- On the right we see what happened
after time
- High diversity there were low
infectious rate
- Diversity in the community helps reduce incidence of disease
- Ecosystem Services: Natural processes that sustain (human) life and depend on the
functional integrity of natural communities and ecosystems
- Species diversity increases:
- Food and fuel production
- Air and water purification
- Ground water recharge
- Decomposition if waste
- Pollination of crops and natural vegetation
- O2 and CO2 change
- Protection from catastrophic events (floods)
- Diversity-function relationships and mechanisms:
a) Complementary Hypothesis
- Linear relationship as seen on left
- Each species has a unique
function n a community (each red
curve is a species)
- No overlap
- Function increases with species richness
- All species have an equal strength of their functions
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b) Redundancy (Rivet) Hypothesis
- Non linear function
- There are overlap functions among
species in a community
- Maximum community function is achieved before maximum richness
- Assumes all species have equal strength of function
- Analogy of an airplane (rivets)
- If 1 or 2 riots are removed nothing happens but theres a max before plane is no longer
functional
i)
Drought resistance is related to species richness
- More species means more drought resistance
- Lost less biomass
ii) Plot biomass is related to species richness
c) Idiosyncratic Hypothesis
- No relationship between species
richness and community function
- Dominant species could be keystone
predators or foundation species which
lead to spikes
Chapter 20
1. Energy In Ecosystems Originates With Primary Production by Autotrophs
- Ecosystems need energy to function
- Energy that flows into an ecosystem comes from sunlight captured by the primary producers
and 90% of energy is lost each tropic level
- Primary production = source of energy for all organisms
- 2 types that store energy is C=C double bonds
- Chemosynthesis is the first
- Bacteria create energy
- Photosynthesis is the second type
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- Source of energy I'm fossil fuels
- Source of energy in the food web
- Source of O2 in our atmosphere
- Accounts for the largest movement of CO2 between Earth and its atmosphere
- Rate of primary production (energy stored in C=C)(primary productivity) is measured in
terms of carbon storage (plant biomass)
- All life depends on chemosynthesis and photosynthesis
a) Gross primary production (GPP) is
total ecosystem photosynthesis
- Total amount of carbon fixed by
photosynthesis
- GPP is influenced by:
i)
Climate
- Precipitation and temperature
- Photosynthesis increases with
temperature but we need enough water
so low GPP in parts of Africa
ii) Leaf area index
- The larger the leaf area the more
photosynthetic energy can be captured
- Photosynthesis is proportional to leaf area
index
- Less ground around the plant means more
area
- % Cover measure ignores leaf overlap
- LEI can be 1200% yet light still reaches the
forest floor
- Higher CO2 fixation is mid day
- Bottom is top of canopy
- The more layers the higher the GPP but its not a 1:1 ratio
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b) Net primary production (NPP) is the energy remaining after
respiratory (R) losses
- NPP = GPP - R
- NPP can be allocated to
- Reproduction
- Storage (starch/sugar)
- Defence against herbivory
- Growth
- Allocation of NPP to roots versus shoots is
balanced to match the plants requirements
- Competition for light means more allocation of
water to leaves so less to roots
- Competition for water is the opposite (more NPP to the roots)
- Time of year may also matter (more NPP towards flowers during reproductive season)
- Tundra will have loner roots
c) NPP can be estimated by a number of methods
- NPP is a measure of ecosystem health
- NPP influences the global carbon cycle Marine and terrestrial environment as well as fossil
fuels influence the CO2
- How do ecologists measure NPP?
i)
Terrestrial ecosystems
- Harvest aboveground biomass at the end of growing season
- Labour intensive
- Only measuring above ground NPP
- Remote sensing techniques
- Compare readings at different wavelengths of light
- Vegetation reflects different amounts of sunlight
- Net Ecosystem Exchange (NEE): Direct measure of CO2
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- Use eddy covariance towers
- NEE = GPP -(AR+HR)
- CO2 (ppm) builds up during the night when plants are
respiring
- Graph produced isolines
- Isoline are points of equal CO2 concentration
- High from midnight to 8am (plants respire more at
night and photosynthesize during the day)
ii) Aquatic Ecosystems
- Remote sensing of chlorophyll in the ocean
- Highest NPP in temperate/polar regions and along
coastlines
- Upwelling, estuaries and continental shelves are rich in
nutrients and have lots of algae and chlorophyl
- Eddy covariance measurements are important to understanding global climate change
- Data allows pocky makers to address issues
- Quantifies gas flux by measuring gasses like CO2
2. Net primary production is constrained by both physical and biotic environmental
factors
a) Terrestrial ecosystems
- The concept that plants are constrained by biotic factors (e.g., herbivory) should be familiar to
you by now
- For this set of slides, I will focus on the abiotic constraints
- You have already seen examples of how precipitation limits the global distribution of the
biomes (Unit 1)
- This graph for terrestrial ecosystems shows the relationship between average annual
precipitation (x-axis) and NPP (y-axis)
- NPP increases with precipitation
- At very low levels of precipitation, plant production is limited by reduced photosynthesis
because the stomata close to reduce water loss through evapotranspiration
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- Between 1,500 and 4,000 mm/yr, there is a lot of variability in NPP
- This is due to the variety of ecosystems that can tolerate this range of precipitation
- Given the variety of plant types in these ecosystems, the range in NPP is not surprising
- NPP decreases with higher levels of precipitation
due to there being more cloud cover (reduced
solar radiation), leaching of nutrients into deeper
soil layers and, if the soil becomes flooded,
hypoxia (insufficient oxygen)
ii) Global Temperature
- Globally, NPP increases with temperature
- At low temperatures, the main inhibitor of NPP is
reduced enzyme activity
- As average annual temperatures increase, the
increased variability is due to different ecosystems
found within those climatic zones
- The range on the x-axis stops at 30 degrees
- Above this, depending on the vegetation types, NPP
might decline due to reduced enzyme activity (due to
denaturation) and, in dry environments, stomatal
closure
- Ecosystem desperation (AR + HR) also varies with temperature
- But respiration also increases with
temperature+
- At very low temperature, respiration
increases in homeothermic animals (to help
maintain body temperature)
- As temperatures rise, so does enzymatic
activity, to a point. Very high temperatures will
cause enzymes to denature
- NEE = GPP - (AR + HR)
- What will happen to NEE if R becomes > GPP?
- Remember the equation for NEE (net ecosystem exchange)
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- Let’s do a thought experiment and imagine what might happen to NEE with increased
global climate change
- As the previous slide illustrated, respiration increases with temperature, this is true for
includes autotrophs and heterotrophs, so the blue bar in this graph will be higher under
future climate conditions
- Two slides ago, you saw that NPP increases with temperature; GPP also increases with
temperature
- However, we are losing vegetation due to logging, agriculture and urbanization – who
knows what the future GPP will be? Chances are that it will decrease
- Looking at the graph, can you see that NEE will change under future climatic conditions
- NEE currently has a positive value (green bar higher than blue
bar), which means more carbon dioxide is being removed from
the atmosphere by plants than is released through respiration
- Under a future climate, NEE could have a negative value,
meaning that plants could be a source of carbon dioxide to the
atmosphere, contributing to even more global warming
- Many people think that our best bet to combat global climate
change is to stop logging large tracts of forests and revegetate
as much land as possible
- Tundra and boreal forest, sphagnum bogs are C sink -> C source, further increasing
atmospheric CO2
- We know that a reversal in the direction of NEE has already happened in some
ecosystems
- The tundra, for example, was historically a sink for global carbon (helping to keep our
climate cool)
- As temperatures have risen, the permafrost is melting, and the tundra is switching to
becoming a carbon source
- This switch is due in part to increased respiration and increased decomposition
iii) Nutrients
- The response of NPP to nutrients depends on the type of vegetation in the ecosystem
- These data are from a series of studies in the mountains in Colorado
- Three species of sedge and three species of grass are plotted across the x-axis
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- The increase in biomass for each species in response to being fertilized with nitrogen (N) is
shown on they-axis
- In general, the grasses responded more to added N than did the sedges, but there are
varying responses even among sedges and among grasses
- In general, sedges live in resource-poor
communities and grasses live in relatively
resource-rich communities
- Plants that are adapted to resource-poor
conditions tend to have slower intrinsic growth
rates than plants that are adapted to resource-rich
conditions
- Ecologists think that species with a faster intrinsic
growth rate are better able to compete for those
resources, and better able to respond to an increased resource supply (in this case N)
b) Aquatic Ecosystems
- NPP is controlled primarily by nutrient availability
i)
Lentic (still water) ecosystems:
- NPP in aquatic systems is limited by nutrient availability
- In lakes, the limiting nutrients are most often phosphorus (P) and nitrogen (N) and the
primary contributors to NPP are cyanobacteria
(photosynthetic bacteria) and green algae
- This picture is of Lake 226 in the Experimental Lakes
Area (ELA)
- In this lake, a barrier was placed across the narrow
part, and nutrients were added to both sides of the
curtain
- On the side with P, cyanobacteria populations
increased dramatically, so much as to change the
colour of the water
- The cyanobacteria consumed most of the oxygen and
the fish suffocated
- The results of this experiment are the reason phosphates are no longer permitted in
detergents, which end up in water systems after items are washed
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- The ELA is a region just south-west of Kenora Ontario that contain 58 small lakes
- Scientists have used these lakes for decades to test ecological theories and run controlled
experiments
- The ELA has an international reputation for outstanding research on lake ecology
- Former Prime Minister Stephen Harper tried to shut down the ELA by cutting its funding
- Scientists around the globe cried out and lobbied their politicians to prevent the closure
- Since 2013, the ELA has been run by an international consortium whose members include
the United Nations, federal governments of several countries, international organizations and
philanthropic foundations
ii) Lotic (flowing water) Ecosystems
- In rivers and streams, energy in the form of organic matter from dead and decomposing
organisms is washed in from the surrounding land
- Relatively less energy is fixed by the primary producers near and in the water (e.g.,
macrophytes and algae)
- Within lotic systems, NPP is limited by N, P and turbidity
- Wind and water currents bring sediments into the water column, making it turbid (cloudy) and
reducing the amount of solar radiation available to phytoplankton
iii) Ocean Ecosystems
- The NPP of northern marine systems is typically limited by N whereas southern and tropical
marine systems are typically limited by iron (Fe)
- Globally, the major contributors to NPP in the ocean ecosystem are picoplankton (less than 1
micrometer in size) and other phytoplankton, with seagrass and kelp contributing near coasts
3. Global patterns of net primary production reflect climate constraints and biome types
- Most of the earths surface has low NOPP
- Peak in terrestrial tropics
- NPP is higher in land masses low of the equator
because theres more land mass north of the
equator
- Peak in oceans at 40 degrees south due to up
welling in estuaries
- There are biome level
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- 1/3 of terrestrial nap is in terrestrial rainforests
- 1% is in the tundra
- 70% is in the tropical forests, Savannah and temperate
- We are loosing these regions due to agriculture
- There will be loss of energy to all trophic levels
- Earth is loosing ability to store carbon in vegetation
which increases global warming
- Summary of global NPP patterns on right
- Most of earths surface is covered in water but it only
makes up 40% of global NPP
- Many controls over NPP
- In terrestrial forests theres leaf area index, length
of growing season, different types f
photosynthesis, plant growth form and Biome
type (climate)
- In the ocean system NPP is controlled by
availability of nutrients
- On the right shows amount of NPP for different
ecosystem types
- Within the terrestrial theres a wide array of NPP
- High in swamps and marshes due to
decomposition
- In aquatic estuaries have high NPP because nutrients are being carried to coast lines
through rivers
- If we wanna regain con tool over the global carbon cycle we would wanna target places
like Estuaries and swamps for restoration and conservation
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Chapter 21
- Autotrophs produce energy
- We need them for any food chain or food web
- Also need them in oceans (like kelp) produce algal bloom to give energy to the system
1. Trophic levels describe the feeding positions of groups of organisms in ecosystems
- Interactions such as ants that cut the leaf are the second level in the trophic system
- We need simple systems to understand
- Many organisms can interact on one organisms
- Many things can eat the same thing)
- Insects are usually primary consumers
- Insects can be predated upon by scorpions for example
- We need to look at who's eating who to make a food web
- When wee understand individual behaviour ours we can
understand trophic levels and the food web
- Many of these arrows go back (curved) which means
individual species have life histories so as a young they can feed
on different things compared to when they are grown
- Can be cannibalistic and feed on their own young
- Most ecosystems have 4 or fewer trophic levels
- Trophic levels is how energy passes through the system
- Primary produces, primary consumers, secondary consumers and tertiary consumers
- Omnivores feed at multiple trophic levels
- Herbivores are often opportunistic
- Detritivores or decomposers
- Worms, mushrooms, insects and bacteria
- When an animal dies they add to the soil and are broken
down
- Detritivores can also break down poop
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- These detritivores are gonna be at the level of the herbivores (primary consumers and can
be eaten by primary carnivores which are secondary consumers)
- We have organisms that eat bacteria as well
- An ecosystem is just a collection of organisms
- Autochthonous is when the source of energy (autotrophs) is within the system
- Plants for example
- Most streams do not produce their own energy
- Allochthonous input is when we input the energy
2. The amount of energy transferred from one trophic level to
the next defend on food quality and on consumer abundance
and physiology
- Energy flow between trophic levels can be depicted using
energy or biomass pyramids
- Less energy at the top
- More energy at the bottom
- Remember 90% is lost each time
- Also more abundance at each level (more grass than
hawks)
- Loss in diversity and abundance eat the top
- What do pyramids look like for terrestrial ecosystems?
- Look to the right
- as energy moves there are fewer individuals and fewer different species
- Energy is reflective to biomass
- Rates of primary productivity far exceed rates of
herbivory
- More plants than monkeys for example
- There is a positive relationship between NPP and
the amount of biomass consumed by herbivores
- Terrestrial herbivores consume less
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- About 13% of terrestrial NPP is consumed (range 0.1% to
75%)
- About 35% of aquatic NPP is consumed (range 0.1% to
75%)
- Big difference
- Because of this relationship trophic pyramids are often
inverted
- Flip in BIOMASS
- Why is that? more primary producers but less biomass but
why?
- Lots of sharks less plants which is a healthy reef
- Pyramid is inverted when you have very nutrient poor waters
- Happens in open oceans and costal oceans mostly
- Some parts of open ocean can be regular
- Costal oceans have higher productivity areas with upwelling
- Majority of fresh water lakes are regular
- Some lakes are inverted when they have low productivity
- On the log graph to the right
- Positive relationship between these 2
- Greater increase in NPP means more consumption by the
heterotrophs
- Overall at ay point you see the amount consumed by the
aquatic ecosystems is greater than that of the terrestrial
- Marshes are similar to aquatic which is why they are highly
productive
- Low NPP is marine algae beds
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Why dont terrestrial herbivores consume more of the available biomass?
- 1. Herbivores are constrained by predators (or viruses) and never reach carrying capacity
- 2, Autotrophs have defences against herby such as secondary compounds
- Plants of resource poor environments tend to have stronger defences that plants from
resource rich environments
- Unicellular algae generally lack chemical and structural defences
- Plant defend themselves well
3. Terrestrial plants have structural components such as cellulose which have few nutrients and
phytoplankton are more nutritious for herbivores than terrestrial plants
- Why dont terrestrial herbivores consume more of the
available biomass?
- Predation
- Plant defences
- Food quality C:N
- Energy flow and trophic efficiency
- Figure on the right
- A lot of this biomass id going right into the detritus of
the system (dying and breaking down), is not invested
and enters the pool where the decomposers play a part
- Consumption efficiency is the proportion of the available biomass that
is ingested by consumers
- Production efficiency is the proportion of assimilated biomass used to
produce new consumer biomass
- This varies depending on the kind of animal you are
- Endotherms products and sustain their own heat and have a low
efficiency compared to ectotherms like insects
- Small mammals are very inefficient
- Carnivore ectotherms are very efficient
- Herbivore ectotherms are very efficient
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- Trophic efficiencies can influence population dynamics
- Population of sea lions are declining
- Nutritional problem with the system because offspring
were unhealthy
- Small school fish used to be more abundant more are
decreasing
- Starting to eat other fish species
- Eating more COD and other fish and less herring
- Herring are in huge schools
- The proportion of fat and energy per mass of pollock are half of that of the herring
- Herring is rich and more nutritious
- “Junk food hypothesis” Eating a lot of the pollock but not
getting anything nutritious
3. Changes in abundances pr organisms at one trophic level
can influence energy flow at multiple levels
- Trophic cascades are changes in abundance and influence
in each trophic level
- Change in each point can start at the top and work their way
down or the opposite
- Rates of consumption at the highest trophic levels determine
species composition and abundance at lower trophic levels which in turn determine rates of
NPP
- Greater availability of limiting resources increase NPP
- Can be in terrestrial and marine environments
- Trickle down through multiple trophic levels
- 2 examples:
- 1) An aquatic trophy cascade (freshwater stream)
- 2) A terrestrial trophic cascade (tropical rainforest)
- The sea otter eats a variety of prey but love sea urchins so have a
negative effect on the population of sea urchins
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- Sea urchins can have a negative effect on the Kelp therefore the otter indirectly has a
positive effect on the kelp
- Killer whales can add to this effect as well
- They hunt salmon and larger prey like sharks
- Top consumer in this ecosystem
- Whales started to kill the otters
- Once this stated to happen this released the sea urchins and the
abundance increases and destroyed help beds
- Massive death cut the roots
- Urchin baron is when they eat all the kelp beds
- Shift between 2 stable states brought about a change by the killer
whale
- Probably came from us hunting prey of the killer whale after 1990
- Strength of the effects are indicated by the thickness of the arrows
- What determine the number of trophic levels?
- There are three possible mechanisms
- Frequency of disturbances
- If we have a high frequency of disturbance (like drought)
- Energy that goes into a system
- Ecosystem size
- The larger the island the more trophic levels it sustained
4. Food webs are conceptual models of the trophic interactions of organisms in an ecosystem
- When starfish are removed a lot of things happen because it interacts with so many things
- Food webs are complex
- The strength of trophic interactions are variable
- Does complexity enhance stability in food webs?
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Chapter 23
- Humans have contributed to extinction for a long time
- We found out about extinction was actually a thing 200 years ago discovered by George
Couvier
- Caused by humans
- The passenger pigeon: From great abundance to
extinction
- The last dies in Cincinnati Zoo in 1914
- Huge number of threatened species around the
world
- Conservation Biology is cheaper 23
1. Conservation biology is an integrative discipline
that applies the principals of ecology to the
protection of biodiversity
- We are facing the 6th mass extinction
- Percentage of species threatened is huge
- Abundance and diversity is dropping a lot in insects too
- Finding successful management will involve working with farmers, fishers, landers, tourists,
artists and such integrative approaches are key to conservation biology
- Conservation Biology: The scientific study of biodiversity, how human activity impact it and
how to maintain it and prevent its loss
- We are dependant on ecosystem services
- Water purification
- Generation and maintenance of soils
- Pollination of crops
- Climate regulation
- Flood control
- Source of food like fish
- These functions depend on the integrity of natural communities and ecosystems
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- For emotional health, most of us require time spent surrounded by natures beauty and
complexity
- Spiritually we go to natural ecosystems for solace, wonder and insight
- Dr Lamb a marine disease ecologist at Cornell found seagrass meadows help remove
dangerous bacteria from the ocean but as we expose ourselves to nature we expose
ourselves to pathogens in other organisms
- Seagrass is at risk
- Are natural resources simply commodities awaiting human extraction? Do we have a moral
obligation to other species?
2. Biodiversity is declining globally
- Biodiversity
- Species diversity
- Genetic diversity within a species
- i.e. diversity in the human race
- Diversity of communities across landscapes
- Coral and symbiodinium
- Speciation and extinction are natural parts of ecosystems
- Rates of extinction are difficult to measure because the number of
species on Earth currently is unknown
- Extinction rates estimated from the fossil record are used as
background rates
- For mammals and birds the background rate is one
species every 200 years
- The are at which Earth is loosing species is
accelerating…(graph on the right)
- Human induced
- Mammals and birds are the highest
- Compared to background rate on the bottom
- Hockey stick graph
- Some people are gonna challenge the models
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- It is sometimes difficult to now when a species is definitely extinct
- Many species are known from a single specimen
or location; the logistics od relocating them may
be insurmountable
- Might just be in a low population cycle
- Loss of forest cover in Western Ecuador
- A. Gentry mapped plant diversity in Central and
South America Estimates the loss of more than
1000 endemic species
- Smaller green means declining bio diversity
- The old growth forest is disappearing and only on Vancouver Island in small patches
- With the disappearance of the forest we loose the spotted owl and marbled murrelet,
American marten and the fisher
- Clear cutting forests
- Estimates on current extinction rates rely on:
- The species area relationship
- Changes in the threat status of species (e.g. shift from endangered to critically
endangered)
- Rates of population decline or range contraction of common species
- Current extinction rate for mammals and birds is 1 per year
- Overall, extinction rates in the 20th century were 100 to 1000 times higher than the
background rate
- For mammals and birds the
BACKGROUND rate is one species
every 200 years
- The Grey Wolf
- Range shrunk by a lot
- That impacts many different
communities around the US
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- Declining biodiversity on Eua
- Island biogeographic work by Steadman 1995
- An sailed in the nation of Tonga
- Fossils were used to estimate the number on the island
3000 years ago
- When humans arrived 3000 years ago immediately
there was extinction of species
- Humans have been causing extinction for millennia
- The extinction of 50% or more of the frugivores and
nectavores probably led to changes in the islands plant
community
- The stronger the interactions of a species in a food web,
the greater effect of its removal
- Earths biota is becoming increasingly homogenized
- Might have to stop going on vacations
3. Primary threats to biodiversity include a invasive species,
b) overexploitation c) pollution d) disease e) climate change f)
habitat loss
- Habitat loss and degradation are the most important threats to diversity
- Degradation is like farming and putting to much nitrogen in the soil which goes into our
rivers and degrade the river (imbalance)
- Fragmentation such as the highway breaks up habitats into parts and can affect some
species
- Zebra mussels attach to boats of people moving through harbours and travel canal to canal
- Invasive
- Outcompete other local endemic fresh water
species
a) Invasive species
- Number of invasive species are rising
- Started in 1790 because of transition from doing
things through hands to power and electricity
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- Cargo boats required to take on water to stable water,
and then dump water at different ports
- A lot of animals are tiny larval stages so boats can
carry these animals far
- Green crab was carries for example from Europe to all
over the world (Canada, US, South America)
b) Exploitation
- First thing explored was Cod
- Huge fish with big harvest for food1850 had a steady increase in tons of cod caught (we
are getting better at fishing due to technology)
- Super huge increase with machines
- Less fish so they are harder to find and catch now
- Species of fish are also getting smaller
- Oceans are being over exploited
- We also over exploited the American Bison close to extinction
- Same with buffalo
- Same with rhino, we are still hunting them for their horns and heads
c) Pollution
- Marine example on top right
- Micro plastics in the ocean
- Pollutants move UP the food chain
- The top graph are PCBs
- To become a top predator you need to eat a lot of flesh
- Biomagnifying PCB concentration
- Large predatory animals eat smaller animals and have high toxicity
- Whale meat for example have a lot of pollutants in them, we should not be eating them
d) Diseases
- Tasmanian tiger (thylacine) is now extinct due to disease
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- Extinction Vortex: A cyclic chain of events causes a small population to decline even further
and become even more vulnerable to processes that lead to extinction
- Loss of habitat then loss of members, then disease
- Tasmanian devil is now threatened
- Facial tumour disease
- Diseases hit hard in small populations with loss of
habitat
- i.e. Isolation in zoos
- Due to loss of genetic diversity
e) Climate Change
- Corals for example are dying due to the
temperature in the ocean breaking the symbolic
relationship they have with they simbiodinum
- Water is becoming more acidic
- Rapid change and degradation of many
ecosystems around the world
- Polar bears are starving
- Hunt seal on ice but when ice melts they cant
hunt
- Image on the right is showing where we should but
our effort for habitats
- Climate change is increasing everywhere (used to be low cuz green but now rapidly
increasing)
- Habitat loss is also increasing
- We need to turn these arrows
e) Habitat Loss
- Humans have modified 60% of Earths land surface and all marine ecosystems have been
impacted
- Homo sapiens is now appropriating 25% of Earths primary production
- Habitat loss: Conversion of ecosystem to another use
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- Habitat Fragmentation: Breaking up continuous habitat into patches amid a humandominated landscape
- Habitat Degradation: Changes that reduce quality of the habitat for many years
4. Conservation Biologists: An example from the ocean waters of Belize
- Many sharks
- Dr. Rachel Graham is director of the wildlife conservation society Gulf and Caribbean Sharks
and Rays Program
- Tagging sharks
- Finding a successful management will involve working with farmers fishers landowners
tourists artists and such integrative approaches are key to conservation biology
- Costa Rica is involved in shark finning
Chapter 24
- Landscape ecology looks at the habitat and its complexity
- Given this area of land what species and ecosystems can we maintain
- Brought wolves back to yellow stone park
- Reproduces greatly
- Wolf is apex predator and hunt bison and elk
- Wolf eat the elk and change their behaviour, moved the elk out of certain areas of the
forest and then the plant population they now have eat effected beavers which are
ecosystem engineers and therefore one thing can change everything
1. Landscape ecology examines spatial patterns and their relationship to ecological processes
- Landscape: An area that is spatially heterogeneous in one or more features of the
environments such as the number of arrangement of different habitat types; a landscape
typically included multiple ecosystems
- SPECIALLY HETEROGENEOUS WITH RESPECT TO ONE ELEMENT OR FEATURE
- Not necessarily great for wildlife
- Natural forests are messy
- Landscape heterogeneity or diversity is essential to forest landscapes
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- Disturbances can shape landscape patterns
- Such as forest fires create breaks and change the
habitat and the species living there
- Species have to disperse
- Movement is important to landscape ecologists
- Patches are main parts of habitat and arrows
represent movement
- Thicker the arrow the stronger the movement
- Matrix 2 seems easer to more to
- Looking at the boreal chorus frog the scale at which
the frog operates is different from other animals
- Wolf can move through a big dry area but frogs cant
- Lodgepole Pine Forests on the right
- Big red area is more homogeneous and less
fragmented
- Gray is higher fragmentation
- Soil types are also important
- Diversity in soil type influences plant and animal types
- Landscape ecologists look at the spatial arrangement of
landscape elements: forest patches, soil types, lakes,
across earth surface
- These patterns influence what species live in an area and
the dynamics of ecological processes
- We can map out species potentials (where they can live) and
where they actually live (red spots)
- If we protect blue spots we can attract more species and
save them
- Ecosystems that make up a landscape are dynamic.
Interactions include flow of water, energy, nutrients or pollutants between ecosystems
- Biotic flow: animals, seeds, pollen etc move between ecosystems. Patches must be
connected or the surrounded habitat (the matrix) must be suitable for dispersal (plant native)
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2. Habitat loss and fragmentation decrease habitat area, isolate populations, and after
conditions at habitat edges
- Fragmentation results in increasing degradation and edge effects
- Fragmentation results in spacial isolation of populations making them vulnerable to the
problems of small populations
- Fenders blue butterfly
- Eucalyptus forest in Western Australia
- The typical blue haze in Jamison Valley can be found in Australia
- Areas of the forests are cleared for grazing
- Further and further fragmented over time
- Only a few patches of forest remain
- Fragmentation leads to loss of top predators giving rise to cascading effects
- King parrot and booboos owl disappear with increase fragmentation
- Tree kangaroos and koalas also disappear because they specialize eating one plant
(eucalyptus)
- Cant move from patch to patch because they are slow moving
- When habitats become fragmented species go extinct in many of the fragments
- There may be inadequate resources, disruption of mutualism or not enough range for
foraging
- But some species flourish under the unchanged
conditions
- The white footed mouse around the Hudson river
- Over time patches become smaller and we find that
top predators disappear so they prey is free to roam
and go up
- White footed mouse harbours bacteria and can get in
us by ticks
- Disappearance of barn owl we are more likely to get
lime disease
- More fragmented forests mean we are more likely to get lime disease
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- Edges (total length of habitat boundary) increase as
fragmentation increases
- Edge effects are biotic and abiotic changes associated
with this boundary
- The physical environment changes over a certain
distance into the fragment and this biological
interactions and ecological processes change as well
- What happens to that environment?
- More wind in the forest so increase in evaporation and
loss of moisture in the soil
- Solar radiation is coming in more
- Temperature is gonna go up so it will be warmer
- Forest fires in Australia are burning a lot of the
Eucalyptus forests
- Many Koalas died
3. Biodiversity can best be sustained by large reserves
connected across the landscape and buffered from areas
of intense human use
- Yellow stone national is a conglomerate of many parks
- Put aside for interest from loggers
- Some spatial designs are better than others for
fostering biodiversity
- Large compact and connected reserves are usually
ideal
- Smaller or disconnected reserves may sometime be
more desirable (e.g. diseases would spread less
quickly in isolated patches)
- Better vs worse on right
- Highway grass bridges are good habitat corridors to allow species to go from one size of the
highway to another
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4. Ecosystem management is a collaborative process
with the maintenance of longer term ecological integrity
as its core value
- Adding wolves into the park like in the movie was
controversial
- As the willows grew, they provided the beaver with a
source of food which resulted in more dams and
change the slow of the parks rivers
- When wolves are absent what do we see
- We see elk browse more heavily on particular
plants which results in less beavers
- Everything is interconnected in a web
- Top apex predators belong in webs
- Humans swerve to purposely hit turtles
- Disappearance of trees
- Only left in national parks
- The challenges will be considerable
- Ecologists have the critical role of providing the
scientific information needed to make decisions
- We are endangered too
Chapter 25
- Global temperature is rising and the poles are getting warmer
- Wind moves energy and heat
- Ocean conveyer belt
- Movements of biologically important elements are linked
at a global scale and they transcend ecological
boundaries
- ecological processes at the ecosystem scale (e.g. net
primary production, decomposition) influence global
phenomena (e.g. greenhouse gas emissions and
uptake)
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- Ecology is in terms of hierarchy
- Organisms then populations then communities within ecosystems in landscapes in the
biosphere
- Top pic is only a small part of a whole reef (Mesoamerican reef)
- Humans are increasingly changing the physical and chemical environment on a global scale
- Atmospheric emissions of pollutants, dust and greenhouse gases have causes widespread
environmental problems
- A major focus of global ecology is the study of the environmental effects of human activities
1. Elements move along geology atmospheric,
oceanic and biological pools at a global scale
- Carbon can be down in forests (vegetation)
- Atmospheres
- Rocks
- Soil
- Benthic sediments
- Surface ocean waters
- Marine biota
- Deep ocean waters
- Very all 8
- Measured in pg (petagram) smallest in marine biota
- Carbon! How does it move around?
- Fluxes
- C is critical for energy trainer and the construction of biomass
- From the atmosphere plants take up carbon by
photosynthesis
- Next flux is decomposition to the soils
- Next flux is transport in rivers to benthic sediments
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- Over all the 3 fluxes respiration occurs in terms of the plants soils and
benthic sediments all from the atmosphere
- Diffusion is first flux from atmosphere to surface ocean
waters
- Next flex is photosynthesis to marine biota
- Last flux is ? to the deep water
- Most of the shallow water is occurring in 200 meter zone
but theres an extra 3700 deep water zone that needs flux
(the?)
- Occurs through downwelling (ocean conveyer belt) and by
dinking detritus (broken organic material)
- Some upwelling and geological time scale up lifting of
limestone plate
- Also ventilation and biological pump
- Cycle of carbon on the right
- Something is missing
- We live in a carbon consuming world
- We need to feed ourselves
- Boating contributes to this by burning fossil fuels
- We've made them part of the carbon cycle
- The global carbon
cycle
- Look at values
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- When Carbon goes into the atmosphere is heats it up
- Its green house gas
- Anthropogenic release of C to the atmosphere from
terrestrial pool results from land use change, mostly
deforestation (20%)
- Before the mid nineteenth century, deforestation was
the main anthropogenic flux
- Removing the forest canopy warms the soil increasing
rates of decomposition and respiration
- Burning trees releases CO2 and small amounts of Co
and CH4
- Anthropogenic effects are now from burning fossil fuels
(80%)
- In the 20th century major deforestation shifted from the
mid latitudes to the tropics
- Anthropogenic emissions of CO2 more than doubles from
1970 to 2011
- Main problems are soils becoming exposed from
deforestation as well as fossil fuels
- Atmospheric CO2 affects ocean pH by diffusing in and forming carbonic acid
- Ocean needs to be alkaline and not acidic
- Changing the pH has strong selection against some organisms
- Corals are being impacted
- Anthropogenic emissions of CH4 have also increased
- Atmospheric CH4 levels are much lower than CO2 but CH4 is more effective greenhouse gas
- CH4 is emitted naturally by anaerobic methanogenic bacteria that live in wetlands , shallow
sediments and in rumens or ruminant animals
- Anthropogenic sources of methane CH4 include:
- Burning fossil fuels
- Agricultural development (primarily rice grown in flooded fields)
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- Burning of forests and crops
- Livestock production
- Ruminate cattle are in huge groups and fart to produce methane
- Climate change, specially change in frequency of extreme events (droughts, storms) will have
profound effects on ecosystems
- Extreme events are often critical in determining species geographic ranges
- Sea level is rising
- Forest fires
- Flooding
- Melting ice caps
- Earth is warming because of anthropogenic emissions of greenhouse gases
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