Evolutionary Theory Exam II - Evolutionary Theory Exam II...

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Evolutionary Theory Exam II Vocabulary: Species Richness :: biodiversity; speciation as we observe today. Extinct : Organisms and populations that could not adapt over time. *99% of all living things that have once lived on this biosphere have now gone extinct.* Population : Species that occupy a certain area Natural Selection: Evolutionary change comes about because of the selection for individuals that survive in nature because of their better- adapted combination of heritable characters, which are then passed onto the next generation Intergradation: infraspecific gene flow from other populations of the same species with different gene frequencies/phenotypes that apps new genetic combinations to a population *microevolutionary change; gene flow from other populations of its own species Polymorphism: natural selection for more than one phenotype in a population. Founders Effect: common type of genetic drift where a small founding population colonizing a new area becomes genetically separated from its ancestors gene pool, but contains less genetic variation than what was found in its ancestors gene pool. *The genetic loss is due to a chance difference in the gene pool of the founding population because small populations (founders) have a higher chance not containing all the genetic variation found in the gene pool from the larger population (ancestors) from which it came. Punctuated Equilibrium: new forms develop rapidly and then remain virtually unchanged until going extinct. Allopatric: sister species occupy different geographic areas Speciation that involves geographic separation of the new population from its ancestor. The alpha model in animals and many sexually reproducing animals. Includes both vicariance and dispersal methods. Hybridization is nonexistent because of geographic isolation Cladogenesis: species branching (splitting) off their ancestor Morphological Species: morphological similarity between species. All members of the same species resemble each other. Hardy-Weinberg Equilibrium: states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. Hybrid Sterility: produces a mule Polyphyletic: a classified group of organisms at a particular level of the classification hierarchy, all of whose members do not share a common ancestor. Ecotone: intermediate environmental structure.
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The size of the ecotone depends on how gradually or abruptly the environment changes. Primary Intergradation: Phenotypically different populations that have never been geographically separated, but because the intergrade zone is not abrupt there is no way to draw a boundary to taxonomically define either population as a separate taxon (ex: subspecies) Step-Cline: abrupt changes in geographic variation caused by sudden environmental changes in space with a narrow zone of primary intergradation, or due to secondary intergradation Species Evenness Grade: refers to a new condition in the morphology and/or evolutionary change
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