BIOL 180 Chapter 27: Speciation Pg. 490-493
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BIOL 180 Full Course Notes
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Document Summary
A species is defined as an evolutionary independent population or group of populations: criteria that can be used to identify species: (1) biological species concept (2) morphospecies concept (3) phylogenetic species concept. According to biological species concept, main criterion for identifying species is reproductive isolation: logical because no gene flow happens between populations that are reproductively isolated from each other. Specifically, if 2 different populations don"t interbreed naturally, or fail to produce viable/fertile offspring when matings take place, they are considered distinct species. Ernst mayr strongly supports biological species concept because criterion of reproductive isolation enables clear evidence of evolutionary independence. Reproductive isolation can result from wide variety of events/processes: mechanisms that stop gene flow between populations: Prezygotic (before-zygote) isolation - prevents individuals of different species from mating. Postzygotic (after-zygote) isolation - offspring of matings between members of different species do not survive or reproduce.
