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Chapter 5

NATS 1840 Chapter Notes - Chapter 5: Ecological Niche

Natural Science
Course Code
NATS 1840
Carl Wolfe

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Ecological Niche: A species way of life or functional role in a community or ecosystem,
involves everything that affects its survival and reproduction
- The adaptations (adaptive traits)
- Range of tolerance for various physical and chemical conditions such as temperature
- Amounts and types of resources used by the species
- How it interacts with other species
- The role it plays in energy flow and matter cycling the ecosystem
Habitat: Physical location where it lives
“Niche is like a species occupation whereas a habitat is like their address”
Fundamental Niche: the full potential range of physical, chemical, and biological conditions
and resources it could use if there were no other competition from other species.
- The niches of species overlap, therefore in an ecosystem there is competition among
species for these resources
Realized Niche: a species usually occupies only part of its fundamental niche in an ecosystem
due to competition.
Generalist Species: Broad niches, they can live in many different places, eat a variety of foods,
and tolerate a wide range of environmental conditions
- Racoons, humans, mice
Specialist Species: narrow niches, they can live in one habitat, only few types of food, tolerate
a narrow range of environments. More prone to extinction when environmental change occurs.
Divergent Evolution: evolution of a single species into a variety of similar species with
specialized niches
- Over time one species may evolve into a variety of species with different adaptations
that reduce competition and allows them to share limited resources. Adds biodiversity
Convergent Evolution: When two distantly related groups of organisms develop similarities
because they are adapting to the same environmental constraints.
What Limits Adaption?
- A population's ability to adapt to new environmental conditions is limited by its gene pool
and how fast it can reproduce.
- A change in environmental conditions can lead to adaptation only for genetic traits
already present in the gene pool of the population.
- Even if a beneficial heritable trait is present in a population the population's ability to
adapt may be limited by its reproductive capacity.
- Species that reproduce quickly such as mosquitoes and bacteria can adapt to
changes in environmental conditions quickly, compared to species such as
humans and tigers that can not because they can not produce offspring quickly.
- Adaptation through natural selection can take millions of years
Two Misconceptions About Evolution
1) Organisms evolve in response to the use and disuse of different structures
2) Survival of the fittest means survival of the strongest
a) Fittest is a measure of reproductive success, the fittest individuals leave the most
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