First Half Definitions

First Half Definitions - First Half Definitions Evolution:...

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First Half Definitions Evolution: Change in genetic makeup (gene frequencies) of populations over time (generations) Microevolution: Gradual change occurring below species level Darwin/Wallace Theory of Natural Selection Organisms are variable at the level of individuals Individual characters are heritable by offspring More organisms are produced than can survive Natural selection leads to survival of best adapted (fittest) Surviving individuals pass on characters leading to gradual population changes over long periods of time Macroevolution: evolution occurring on a grand scale of time and geography Modern Ideas in Macroevolution (S.J. Gould) Extinction events are more common than we think and there is no adaptation for these meaning chance can play a role as to which major groups dominate. Right place/time. Theory of Punctuated Equilibria: Evolution may occur by rapid bursts followed by periods of tranquility. Ex: Ferns rapidly replacing conifers when Earth cooled in Permian. Species Concept Biological Species Concept Species are populations of individuals which can interbreed with each other but not with other groups. Species are genetically isolated Some plants can form fertile hybrids but these have little potential to breed. Phylogenetic Species Concept Population that has evolved long enough to have traits that are statistically different implying genetic isolation. Processes of Evolution Allopatric Speciation “Other Place” Geographic Isolation : Geographic boundaries isolating populations and they evolve over time to become different species. Ex: Rise of mountains to separate palm species Adaptive Radiation: Species move into new environments and adapt to their
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First Half Definitions - First Half Definitions Evolution:...

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