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17 Cards in this Set
- Front
- Back
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Types of Natural Selection
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Directional, disruptive, stabilizing.
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Directional Selection
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Most common during environmental change. When members of a population migrate to new environment with different conditions.
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Disruptive Selection
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Favors individuals at both extreme phenotypes.
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Stabilizing Selection
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Favors intermediate and acts against extreme phenotypes. Reduces variation.
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Speciation
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Where new species are formed.
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Species
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Reproductive groups that are reproductively isolated from other groups/populations.
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Reproductive isolating mechanisms
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Isolating, geographical, ecological, mechanical, hybrid sterility, ecological.
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Isolating Mechanisms
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Barriers that reduce interbreeding b/w individuals.
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Ecological Isolation
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Different habitats acquire separate groups.
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Geographical Isolation
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Geographic barriers isolate groups.
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Mechanical Isolation
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Physical incompatibility of reproductive structures.
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Hybrid sterility
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Hybrid offspring are sterile.
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Speciation patterns
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Allopatric, sympatric
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Allopatric Speciation
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Population of a single species becomes geographically isolated from eachother. Diverge genetically.
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Sympatric Speciation
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Reproductive isolation/speciation occurs without geographic isolation. 1) Autopolyploidy 2) Allopolyploidy
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Autopolyploidy
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Single species gives rise to another species by doubling its own chromosomes. Auto = self
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Allopolyploidy
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Two different species produce fertile hybrid through doubling chromosome number.
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