PRINCIPLES
OF ECOLOGY
WHAT IS ECOLOGY?
Scientific study of the
interactions among organisms
and their environments.
ASPECTS OF ECOLOGICAL STUDY
 Biosphere:
part of the
Earth that supports life.
 Environment: non living
and living surroundings.
 Abiotic factors: non living
factors, light, soil.
 Biotic factors: living
organisms interactions.
 Look at the picture. How
do other living organisms
affect the gold fish?
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LEVELS OF ORGANIZATION IN
ECOLOGY
ORGANISM
POPULATION
COMMUNITY
ECOSYSTEM
BIOSPHERE
ORGANISM
 Complete
individual
living being.
POPULATION
A
group of one
species of organisms
that live together in
the same place at
the same time
 Interbreed.
 Share and compete
for resources.
 Adaptations may
reduce competition.
COMMUNITY
A
group of
interbreeding
populations in the
same area at the
same time.
 Changes in one
population affects
another.
ECOSYSTEM
 Composed
of the
interactions
between organisms,
and their
surrounding abiotic
factors.
 Types: terrestrial,
freshwater and
saltwater.
BIOSPHERE
 All
portions of Earth
where life exists.
 Relationship
between all of the
ecosystems.
Organisms in Ecosystems
 HABITAT:
Where the organism lives.
 NICHE: The role and position the species
has in the environment.
Predator prey relationship
lion/zebra
Bear/fish
Predator is the hunter
Prey is the animal being hunted
SYMBIOSIS
Living together of different
species may aid survival.
LIVING RELATIONSHIPS
COMMENSALISM
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Spanish Moss and Tree
MUTUALISM + +
PARASITISM
Anemone and clown fish
Deer tick and deer
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Symbiosis Video
End for TODAY
CYCLES IN NATURE
 Energy
in an ecosystem is replenished by
the sun.
 Matter in an ecosystem has to be
recycled.
 Atoms making up organisms today are
the same as those present when life on
Earth began.
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Water Cycle
The water cycle.
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Precipitation
Evaporation
Condensation
Transpiration
Runoff
Groundwater
The Nitrogen Cycle
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Amino acids and proteins
Atmosphere
Lightning
Bacteria
Waste
Runoff
 Nitrification
– oxidation of ammonia with
O2 to make nitrates
Nitrates are absorbed by plants and
are used for protein absorption
 Denitrification
– nitrate reduction to
produce nitrogen
Nitrogen fixing nodules
 The
bacteria converts the nitrogen that
cant be used by the plants into a useable
form.
 What kind of symbiotic relationship would
this be?
Lightning
 Lightning
breaks nitrogen molecules and
letting nitrogen combine with oxygen in
the air forming nitrogen oxides. These
dissolve in rain, forming nitrates, that are
carried to the earth.
Nitrogen cycle
Stop for now
Carbon Cycle
Carbon Cycle Video
The Carbon Cycle
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Atmosphere
Photosynthesis
Respiration
Wastes
Soil
Fuel
Pollution
NUTRITION AND
ENERGY FLOW
Feeding relationships

Autotroph-Organisms that
produced their own food
CARNIVORE

Heterotroph-Organisms that
must obtain their food from
eating
OMNIVORE
SCAVENGER
HERBIVORE
DECOMPOSER
HOW ORGANISMS OBTAIN
ENERGY
 Producers:
food
AUTOTROPHS make their own
 Consumers:
HETEROTROPHS take their
food in ready made
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Carnivores: meat, hawk
Herbivores: plants, rabbit
Omnivores: meat and plants, bear
Scavengers: carrion, buzzard
 Decomposers:
breakdown and release
nutrients from dead organisms, bacteria
and fungi.
MATTER AND ENERGY FLOW IN ECOSYSTEMS.
 Food
chain: Model used to show how matter
and energy flows through an ecosystem.
 Autotrophs  Heterotrophs  Decomposers
 Usually 3-5 links.
 10% of available energy reaches next link.
Because energy is used/lost as heat at each
link.
 Grass

rabbit

fox
FEEDING LEVELS
 Trophic
level: A feeding step in a food chain.
 (Animal
may occupy more than one trophic level in
an ecosystem.)
 1st
trophic level = green plant = producer
 2nd trophic level = herbivore = primary consumer/1st
order
 3rd trophic level = carnivore = secondary
consumer/2nd order
 4th trophic level = carnivore = tertiary consumer/3rd
order
 5th trophic level = carnivore = quaternary
consumer/4th order
Food web
Model showing all possible feeding
relationships at each trophic level in a
community.
 Network of interlinked food chains

ECOLOGICAL PYRAMIDS
 Shows
how energy flows through an
ecosystem.
 Initial energy source is the sun.
 Autotrophs/1st trophic level at base of all
pyramids.
 Three types
Pyramid of numbers
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Based on population size at each trophic
level.
Populations decrease at each successive
trophic level but inversion possible.
Pyramid of energy
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Based on the amount of energy available at
each trophic level.
Only 10% of the energy is past to the next
level.
Decreases at each level by 90% , this energy
is used or lost as heat.
Pyramid of biomass

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Shows mass of
living material at
each trophic level.
Decreases at
each trophic level
Bioaccumulation/Biomagnification

Bioaccumulation-The accumulation of substances,
such as pesticides or other organic chemicals in
an organism or part of an organism.
 Biomagnification-the
process by which a
compound increases its concentration in the tissues
of organisms as it travels up the food chain.
 Examples:
DDT, Mercury