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Ecology Ch 5
Interactions
Section 1 Habitats and Niches
Introduction
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Ecosystems are a network of interactions
between living things and the environment
Each organism has a means of getting food,
water, living space
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Approached from the evolution principle
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Role in the ecosystem
Adapt to change over time
Ecology is the study of that adaptation
Habitat
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Ecosystem can be very different
Climate
 Organisms
 Conditions
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Organisms must adapt to those conditions
The place an organism lives is called its habitat
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Size varies with the type of organism
Niches
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Each organism had adapted to its habitat
Gathering food
 Reproduction
 Avoiding predators
 Active times
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Their role within the ecosystem is called its
niche
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Includes biotic and abiotic factors
Niches Continued
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All members of a species are adapted to the
same niche
If they are different enough they are a different
species
 Anolis lizard example of two species with similar
niches
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If two different species try to occupy the same
niche it leads to competition
Niche competition
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Competition can lead to extinction
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Competitive exclusion
To avoid competition organisms will go where
there is less competition
Fundamental niche- theoretical niche
 Realized niche- actual niche
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Realized
Niches
Fundamental
Niches
Niche Diversity
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Often controlled by abiotic factors
Temperature
 Moisture
 Predation increases diversity
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Keystone predator causes the most diversity
Robert Paine
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Worked with sea stars
When removed the number of mussels increased
Number of species drops from 15 to 8