Biolog 19 - Chapter 19: Evolutionary Patterns, Rates, and...

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Chapter 19: Evolutionary Patterns, Rates, and Trends I. Reproductive Isolation A. A biological species concept is that species that is one or more groups of individuals that interbreed B. Sibling species are two species that are morphologically similar C. Prezygotic mechanisms stop cross-breeding D. Postzygotic mechanisms kill hybrids or make them weak or infertile E. Reproductive isolating mechanisms Mechanical – body parts of a species are not a physical match with those species that could serve as a mate Temporal – diverging populations cant interbreed when timing of repro differs Behavioral – behavior or courtship displays differ and bar gene flow between two species Ecological – populations differ in microenvironments may be ecologically isolated Gamete Mortality – gametes differ and have molecular incompatibility II. Speciation A. Allopatric – physical barriers stop gene flow between species Gene flow ends and genetic divergences give rise to daughter species
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Biolog 19 - Chapter 19: Evolutionary Patterns, Rates, and...

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