Principles of Ecology
Biology
What is Ecology?
– What is the lowest level of organization that
most ecologists study?
– What name is given to several organisms in
the same species interacting together?
– What factors are included in an ecosystem
that are not included in a community?
– Describe how ecosystems and biomes differ?
– Which level of biological organization is the
most complex?
What is Ecology?
– What is the lowest level of organization that most
ecologists study? organism
– What name is given to several organisms in the same
species interacting together? population
– What factors are included in an ecosystem that are
not included in a community? Abiotic factors
– Describe how ecosystems and biomes differ? Biomes
include several ecosystems over a large area.
– Which level of biological organization is the most
complex? Biosphere
Levels of Organization
• Ecologist study
organisms ranging
from the various
levels of
organization:
– Species
– Population
– Community
– Ecosystem
– Biome
– Biosphere
Interrelationships
• Define the 3 categories of symbiosis and
give an example of each – and record in
your journal/notebook
• What is competition? Give an example.
• What is predation? Give an example
Population – group of individuals of the same species
living in the same area, potentially interacting
Community – group of populations of different species
living in the same area, potentially interacting
What are some ecological interactions?
Why are ecological interactions important?
Interactions can affect distribution and abundance.
Interactions can influence evolution.
Think about how the following interactions can affect
distribution, abundance, and evolution.
Types of ecological interactions
competition
predation
parasitism
mutualism
commensalism
symbiosis
Competition – two species share a requirement for a
limited resource  reduces fitness of one or both species
Predation – one species feeds on another  enhances
fitness of predator but reduces fitness of prey
herbivory is a form of
predation
Parasitism – one species feeds on another  enhances
fitness of parasite but reduces fitness of host
Mutualism – two species provide resources or services
to each other  enhances fitness of both species
Commensalism – one species receives a benefit from
another species  enhances fitness of one species; no
effect on fitness of the other species
Symbiosis – two species live together  can include
parasitism, mutualism, and commensalism
Organizing ecological interactions
effect on species 1
+
effect on
species 2
+
mutualism
0
commensalism
-
predation
herbivory
parasitism
0
-
commensalism
predation
herbivory
parasitism
competition
competition
competition
Ecosystem Interactions
• What is a habitat?
• What is a niche?
Flow of Energy in an Ecosystem
• What are: autotrophs, heterotrophs,
herbivore, carnivore, omnivores,
detritivores
• What is the main energy source for life?
• What is a trophic level?
• How do you draw a food chain, food web?
What is the difference?
• What group is at the top of the pyramid of
energy, biomass, numbers?
How does Energy flow
through an Ecosystem?
• Energy flows
through an
ecosystem in ONE
direction,
– sun or chemicals
– Autotrophs
– heterotrophs
Energy Flow in Ecosystems:
Feeding Relationships
• Food Chain – steps of
organisms transferring
energy by eating &
being eaten
• Food Web – network
of all the food chains
in an ecosystem
Food Web
Ecological Pyramids
• Trophic Level – each step in a food chain or food
web
Biomass Pyramid
Energy Pyramid
Pyramid of Numbers
How does Matter move
through an ecosystem?
• Unlike the one way flow of
energy, matter is recycled
within & between
ecosystems
• Nutrients are passed
between
organisms & the environment
through biogeochemical
cycles
• Biogeochemical Cycles:
– Bio –life
– Geo – Earth
– Chemo – chemical
1.
WATER CYCLE
2.
NUTRIENT CYCLES:
a) CARBON
CYCLE
b) NITROGEN
CYCLE
c) PHOSPHORUS
CYCLE
Why are nutrients important ?
• Every living organism
needs nutrients to
build tissues and
carry out essential
life functions.
95% of your body is made of…
1)
OXYGEN
2)
CARBON
3)
HYDROGEN
4)
NITROGEN
THE WATER CYCLE
Water Cycle 1
• Water
– enters atmosphere by evaporation, transpiration
– leaves atmosphere as precipitation
• Water on land
– filters through ground
– runs off to lakes, rivers, ocean
Water Cycle 2
• Aquifers
– underground caverns, porous layers of rock
– store groundwater
• Runoff
– movement of surface water from land to
ocean
CARBON CYCLE (see fig.3-13)
4 PROCESSES MOVE
CARBON THROUGH
ITS CYCLE:
CO2
1) Biological
2) Geochemical
3) Mixed biochemical
4) Human Activity
CO2
Carbon Cycle
• CO2 gas enters plants, algae, cyanobacteria
– photosynthesis turns CO2 into organic molecules
• Cellular respiration, combustion, erosion of
limestone return CO2 to water, atmosphere
– where it is again available to producers
NITROGEN CYCLE (see fig.3-14)
N2
in Atmosphere
Nitrogen-containing nutrients in
the biosphere include:
1) Ammonia (NH3)
2) Nitrate (NO3-)
3) Nitrite (NO2-)
ORGANISMS NEED
NITROGEN TO MAKE
AMINO ACIDS FOR
BUILDING PROTEINS!!!
N03NH3
&
N02-
Nitrogen Cycle 1
• Nitrogen fixation
– conversion of nitrogen gas to ammonia
• Nitrification
– conversion of ammonia or ammonium to nitrate
Nitrogen Cycle 2
• Assimilation
– conversion of nitrates, ammonia, or ammonium
to proteins, chlorophyll, or nitrogen-containing
compounds (by plants)
– conversion of plant proteins into animal proteins
Nitrogen
Fixation
PHOSPHORUS CYCLE
(see fig.3-15)
PHOSPHORUS FORMS PART OF IMPORTANT LIFE-SUSTAINING
MOLECULES (ex. DNA & RNA)
Phosphorus Cycle 1
• Phosphorus erodes from rock
• Plants absorb inorganic phosphate from
soil (through roots)
• Animals obtain phosphorus from their diets
Phosphorus Cycle 2
• Decomposers release inorganic
phosphate into environment
• Phosphorus washes into ocean
– is deposited in seabeds
– lost from biological cycles for millions of years