BILD 3 Lecture Notes - Lecture 23: Interspecific Competition, Competitive Exclusion Principle, Bild
13 Jun 2018
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BILD 3 Lecture 23
5/30/2018
• Niche
o The environment in which an organism lives in, biotic and abiotic
o Fundamental niche= hypothetical; realized=actual
o An organism’s niche is restricted by its interactions with other individuals
• Interspecific competition
o Is what determines a niche
o There are different species competing for a particular resource that limits growth
or survival
o E.g. light, space, and nutrients
o Competition can decrease population growth rate, either indirectly or directly
▪ Indirectly example= eating the same food
▪ Direct= eating each other
o This between individuals of different species causes a mutually depressing effect
on both populations
▪ If strong enough, interspecific competition can lead to the competitive
exclusion of species from a local site
▪ Competitive exclusion is common in lab experiments- less common in
nature
▪ Factors that promote coexistence in nature:
• Interspecific competition often have niches that differ by some
small factor
• Evolution by natural selection can shape the nice of a species in
response to interspecies competition→have specialized to a
microenvironment
o Interspecies competition leads to competitive exclusion, while intraspecies
competition leads to speciation over time by sympatric habitat differentiation
▪ Individuals within that population at the extremes to use different kinds
of environment leads to habitat differentiation
o If interspecific competition restricts the size of the realized niche of a given
species, then competitor removal expands the realized niche
o Symmetric competition is A approximates B
▪ Less A means more B, and less B means more A
o
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Document Summary
5/30/2018: niche, the environment in which an organism lives in, biotic and abiotic, fundamental niche= hypothetical; realized=actual, an organism"s niche is restricted by its interactions with other individuals. Is what determines a niche: there are different species competing for a particular resource that limits growth or survival, e. g. light, space, and nutrients, competition can decrease population growth rate, either indirectly or directly. Indirectly example= eating the same food: direct= eating each other, this between individuals of different species causes a mutually depressing effect on both populations. If strong enough, interspecific competition can lead to the competitive exclusion of species from a local site: competitive exclusion is common in lab experiments- less common in nature, factors that promote coexistence in nature: Interspecific competition often have niches that differ by some small factor: evolution by natural selection can shape the nice of a species in response to interspecies competition have specialized to a microenvironment.
