ANTH-UA 2 Study Guide - Midterm Guide: Dryopithecus, Paranthropus, Australopithecus

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Stabilizing selection: selection against both extremes or an average. Polymorphism: two or more different phenotypes exist within the same population. Species: a group of related organisms that can interbreed and produce fertile, viable offspring. Speciation: formation of one or more new species. Occurs through reproductive isolation: any mechanism that prevents two populations from exchanging genetic material. Reproductive isolation: any factor, behavioral, ecological or anatomical that disrupts or prevents reproduction. Allopatric: formation of one or more species through geographic isolation. Parapatric: formation of one or more species through continuous populations (some phenotypes are more favorable) (example: ring species) Sympatric: formation of one or more new species through one or more phenotype within a population due to geographical area. Prezygotic: fertilization barriers (example: mate recognition, mechanical issues) Postzygotic: sterility or offspring non-viability (example: horse + donkey = mule) Principle of stratigraphy: the order of rock layers (strata) and the sequence of events they reflect.