Ecology
Chapters 3, 4, 5 & 6
in your textbook
Ecological Levels of Organization
• Species: a group of living organisms consisting of
similar individuals capable of exchanging genes or
interbreeding.
• Population: a group of organisms belonging to the
same species that are living in the same area
• Community: an interacting group of various species in
a common location
Ecological Levels of Organization
• Ecosystem: a system formed by the interaction of a
community of organisms with their environment.
An ecosystem Includes both biotic and abiotic factors
– Biotic Factors: Any living organism or factor created
by a living organism that influences or an ecosystem.
– Abiotic Factors: a nonliving condition or thing, that
influences or affects an ecosystem and the organisms
in it
Ecological Levels of Organization
• Biome: A major ecological community adapted to a
particular climate or environment over a large
geographic area.
1.
3.
5.
7.
Major Biomes of Earth
Tropical Rain forest
2. Tropical Dry forest
Tropical Grassland/Savanna
4. Desert
Temperate Grassland
6. Temperate Forest
Taiga
8. Tundra
Ecological Levels of Organization
• Biosphere: The parts of the Earth where life can
exist; includes the land, water and atmosphere.
Recap: Organization of Living Organisms
Cells
Organ System
Community
Biosphere
→
→
→
Tissues
Organism (Species)
Ecosystem
→
→
→
Organ
→
Population→
Biome
→
LevelsLevels
of Organization
Ecological
of Organization
Ecological Succession
• Succession: the orderly process where a ecosystem
changes over time.
– In each stage of succession a new plant community
replaces the old plant community.
– Each stage of
succession can
support
different
organisms.
Ecological Succession
• Primary Succession: occurs on surfaces that did not
previously support plant life, such as bare rock.
– What can cause primary succession to begin:
volcanic eruptions and melting glaciers
– Pioneer species
(moss and
lichens) can
break down
rock and form
soil.
Ecological Succession
• Secondary Succession: occurs on surfaces that previously
supported plant life, soil is already present.
– What can cause secondary succession to begin:
forest fires, abandoned farmland, deforestation
– Grasses are often the first plant to appear and give rise
to larger plants.
– Climax community: a
stable and unchanging
community established
after succession
Ecological Succession
• Succession: the orderly process where a ecosystem
changes over time.
– In each stage of succession a new plant community
replaces the old plant community.
– Each stage of
succession can
support
different
organisms.
Community Interactions
Symbiosis: any relationship where two species live closely
together.
There are 3 types of symbiotic relationships
1. Mutualism: A
relationship that
benefits both
organisms involved.
– Explain the
relationship between
bees and flowers.
Community Interactions
2. Commensalism: A
relationship where
one organisms
benefits and the other
is unaffected.
3. Parasitism: A relationship
where one organism
(parasite) benefits and
the other organism (host)
is harmed.
Community Interactions
• Competition: occurs when 2 or more individual
simultaneously require a single resource that is in limited
supply
– Competition harms both species that use a limited
resource.
– Niche: The role or
“job” that a
organism performs
in its ecosystem.
Community Interactions
What happens
when two
species try to
occupy the
same niche?
Community Interactions
• Predation: the consumption of one organism (the prey)
by another (predator)
– One organism is benefited and the other is harmed.
– How is predation different than symbiosis?
– Describe the relationship between predator and prey
populations.
Community Interactions
Summary of Community Interactions:
Energy, Producers, and Consumers
• Autotrophs: Use energy from the sun or chemicals to make
“food.”
– Includes plants, algae and certain bacteria.
– Also called producers: They make food available for
other organisms
What is the equation for
photosynthesis?
What is the difference
between chemosynthesis
and photosynthesis?
Energy In An Ecosystem
• Food Chain: Shows the flow of energy
from one organism to another.
• Energy moves from producers to primary
consumer to secondary consumer, etc.
– Producers (autotrophs): make their
own food through photosynthesis or
chemosynthesis.
– Consumers (heterotrophs): obtain
energy by feeding on producers or
other consumers.
– Decomposers (heterotrophs): an
organism that obtains its energy by
breaking down dead and decaying
matter.
Energy In An Ecosystem
Ecological pyramids: an illustration of the reduction in
energy as you move through each trophic level in an
ecosystem.
– Trophic Levels: any class of organisms that occupy
the same position in a food chain
Energy In An Ecosystem
• Food web: interconnected food chains in an ecological
community
What will happen
if the killer whales
disappeared from
the ecosystem?
How will an
increase in leopard
seals affect the krill
population?
Nutrient Cycles
Biogeochemical Cycles:
describe the movement of
elements through an
ecosystem.
• Matter such as carbon,
nitrogen, and water is
recycled through the
ecosystem.
• Energy from the sun is
not recycled, instead it is
lost as heat as it moves
through an ecosystem.
Nutrient Cycles
Nutrient Cycles
1. Water enters the atmosphere by:
•
•
Evaporation – water changes from a liquid to a
gas
Transpiration – Evaporation through leaves
2. As water rises it cools condenses into tiny
droplets that form clouds.
3. Droplets returns to Earth as precipitation.
4. Water enters the rivers, ground water, ocean
or plant roots to restart cycle.
Nutrient Cycles
Nutrient Cycles
1. Volcanoes, respiration, fossil fuels, and
decomposition add CO2 to atmosphere.
2. Plants take CO2 and make carbohydrates
3. Plants are eaten by animals and carbohydrates
are passed through the food chain.
4. As the animal breathes and eventually dies
and decomposes CO2 is returned to
atmosphere.
Nutrient Cycles
Nutrient Cycles
1. Nitrogen gas makes up 78% of atmosphere
2. Nitrogen Fixation: bacteria take nitrogen gases
and turn it into ammonia, nitrite, and nitrate.
3. Plants and animals use nitrates and nitrites to
make proteins and nucleic acids
4. Animal dies and decomposes returning nitrates to
the soil.
5. Denitrification: other bacteria convert nitrates
into nitrogen gas.
6. Humans add nitrogen by fertilizers
http://www.youtube.com/watch?
v=BosHU4ARR9w&feature=relate
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http://www.youtube.com/watch?v=leHy-Y_8nRs
Population Growth
Exponential Growth: When a population grows at a constant
maximum rate.
• Small populations grow slowly
• The larger the population the faster it grows.
• Requires ideal conditions and unlimited resources.
Ex: One bacteria cell
reproduces every 20
minutes. Assume
unlimited resources . . .
– How many bacteria after 1
hour?
– How many bacteria after 2
hours?
– How many after one day?
Population Growth
Logistic Growth: The rate of population grow decreases and
eventually stops due to a limiting factor.
• Carrying Capacity: The maximum population size an
ecosystem can support.
• Limiting factor: any biotic or abiotic factor that prevents a
population from becoming too large.
– Density Dependent
Limiting Factors
– Density Independent
Limiting Factors
• Explain why the rate
of population growth
changes over time.
Population Growth
Observe the graph of human population growth over the past
2,000 years.
• Describe the pattern of
human population
growth.
• What would happen if
the human population
already surpassed the
carrying capacity of the
Earth?
• How has human
overpopulation affected
the environment?
Biodiversity
• Biodiversity is the variety of life forms in an area
– It can be measured in terms of genes, species or ecosystems.
• Ecology: is the study of the relationships between
organisms and their environment.
– All biotic and abiotic
factors in an
ecosystem are
connected.
– Human and natural
disturbances can
impact a single
factor and cause the
entire ecosystem to
change.
Biodiversity
Invasive Species
• Species that are living
outside their normal habitat.
• How do invasive species
decrease biodiversity?
– They prey on native
species.
– They outcompete native
species for limited
resources.
Biodiversity
Global Warming
• Greenhouse Effect
– Carbon dioxide, water vapor and methane
are greenhouse gases.
– All trap heat and hold it next to the surface
– It is a natural process that keeps the temp
suitable for life
• Global Warming
– Human activities, such as burning fossil
fuels, increased the amount of CO2 in the
atmosphere.
– A slight increase in temperature can have a
large impact on the environment.
Biodiversity
Pollution
• Pollution is the addition of
substances, objects, noise or
light that causes harmful
changes to an ecosystem.
• Extremely small concentrations
of chemical pollutants have had
a devastating impacts on the
environment.
• Biological Magnification: the
concentration of harmful
chemicals in organisms increases
as it moves up a food chain.
Biodiversity
Deforestation: The clearing of all trees from an area.
Biodiversity
Monocultures
• Monocultures: when a single
type of crop is planted over a
large area year after year.
• That one variety of crop that is
grown may be highly susceptible
to a certain type of pest or
disease.
• Pesticides and fertilizers used to
grow monoculture crops may be
harmful to the environment.
Biodiversity
Eutrophication:
• Agricultural runoff adds
nutrients to an aquatic
ecosystem.
• This causes algae in the water
to grow quickly (algal bloom)
• Algae will eventually die
because of depletion of
nutrients and sunlight.
• Decomposition of the dead
algae will remove oxygen from
the water.
• Fish and other aquatic
organisms will die from lack of
oxygen.