NOTES 32 – Ecology
What is ecology?
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Ecology – the study of the interactions
between organisms and their environment
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How organisms interact with other organisms
 Ex. a cow elk eats grass, two zebras mate
How organisms interact with non-living things
 Ex. a cow drinks water, people breathe
oxygen
Is it wise to release large amounts of
chemicals into the environment
without fully understanding the
effects on ecology or human health?
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DDT (dichlorodiphenyltrichloroethane )
Kills insects
Stays active in environment for long
periods of time
Mosquito control = reduced spread of disease
Effective against body lice/household insects
Sprayed over larege areas of farmland
What happened?
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DDT runs off from farm land,
enters rivers, lakes, streams
Small fish begin to die
Caused thinner egg shells in
birds, leading to reproductive
problems and death
Scientists discovered DDT in
human body fat and traces of
DDT in the flesh of penguins as
far from civilization as the South
Pole!
DDT is an endocrine disruptor
and a probable carcinogen
(cancer-causing agent)
Why is knowledge of the
environment in which we
live important?
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Silent Spring by Rachel Carson
(1962)
Documents negative effects of
pesticides in the environment
Helped launch the environmental
movement
Lead to DDT ban in 1972
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What is an
okapi?
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Relative of the giraffe
Native to the Ituri
Rainforest, located in the
northeast of the Democratic
Republic of the Congo, in
central Africa
approximately 10,000–
20,000 in the wild
Okapis are herbivores,
eating tree leaves and
buds, grass, ferns, fruit,
and fungi
The tongue of the okapi is
long enough for the animal
to wash its eyelids and
clean its ears (inside and
out)
Biotic factors – living organisms
in an environment

Ex. animals, plants (and their parts), bacteria,
fungi
Abiotic factors – non-living things
in an environment
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Ex. air, temperature, water, light, soil, etc.
Ecologist – a scientist who studies
ecology
What do ecologists study?
Ecologists study the
5 levels of ecological
organization
1. Organisms – single
living things
 Ex. A beaver
gathering food

What do ecologists study?
2. Populations –
groups of organisms
of one species living
in the same place
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Ex. Two beavers
compete for food
What do ecologists study?
3. Communities –
populations of
different species
living in the same
place
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Ex. A bear eats a
beaver
What do ecologists study?
4. Ecosystems – all
the interactions
between the biotic
and abiotic factors in
an environment
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Ex. A beaver builds a
dam creating a pool
in a stream where
fish mate and lay
eggs
What do ecologists study?
5. Biosphere – all the
biotic and abiotic
factors in the part of
the planet that
supports life – from
high in the
mountains to
underground and
deep in the oceans
What do ecologists learn from
their studies?
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How organisms live
How organisms interact with one another
How organisms get their energy and how
energy moves through an ecosystem
How organisms use abiotic factors and
affect their environments
How removing or adding certain biotic
factors might affect an ecosystem
How pollution affects ecosystems