BIOL 2112 Chapter Notes - Chapter 14: Gene Flow, Adaptive Radiation, Sympatric Speciation

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1.Distinguish between microevolution and speciation.
Microevolution- the change in the gene pool of a population from one generation to the
next. This involves evolutionary changes within a population.
Speciation- process by which one species splits into 2 or more species. Each time this
happens, the diversity of life increases. This occurs when a population changes enough that it
diverges from its parent species and becomes a new one.
2.Compare the definitions, advantages, and disadvantages of the different species concepts.
Biological Species concept- Species that can interbreed in nature and they produce fertile
offspring
Reproductive isolation- prevents genetic exchange and maintains a boundary between
species. Occasionally they interbreed and produce hybrids. Example is the grizzly bear and polar
bears reproducing.
Morphological Species concept- classifies organisms by observing physical traits and can
be applied to asexual organisms and fossils.
Ecological species concept- defines a species by their ecological niche and focuses on
unique adaptations to particular roles in a biological community.
Phylogenetic species concept- defines a species as the smallest group of individuals that
share a common ancestor. Biologists use phylogenetic history and compare a species
morphology and DNA sequences.
3.Describe five types of prezygotic barriers and three types of postzygotic barriers that prevent
populations of closely related species from interbreeding.
Prezygotic- prevent mating or fertilization between species
Habitat- lack of opportunity for mates to encounter each other
Temporal-breeding during different season
Behavioral-failure to send/ receive appropriate signals
Mechanical-physical incapability of reproductive parts
Gametical-molecular incapability of eggs and sperm, or pollen and stigma
Postzygotic- operate after hybrid zygotes have formed
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Document Summary

Microevolution- the change in the gene pool of a population from one generation to the next. Speciation- process by which one species splits into 2 or more species. Each time this happens, the diversity of life increases. This occurs when a population changes enough that it diverges from its parent species and becomes a new one. 2. compare the definitions, advantages, and disadvantages of the different species concepts. Biological species concept- species that can interbreed in nature and they produce fertile offspring. Reproductive isolation- prevents genetic exchange and maintains a boundary between species. Example is the grizzly bear and polar bears reproducing. Morphological species concept- classifies organisms by observing physical traits and can be applied to asexual organisms and fossils. Ecological species concept- defines a species by their ecological niche and focuses on unique adaptations to particular roles in a biological community. Phylogenetic species concept- defines a species as the smallest group of individuals that share a common ancestor.

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