BIOL 226 Lecture Notes - Cichlid, Punctuated Equilibrium, Hybrid Zone
29 Jan 2014
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Document Summary
Biological species concept: defined by ernst mayr 1942. Species: population or group of populations whose members have the potential to interbreed and produce viable, fertile offspring. Strength: addresses the mechanism of isolation: criterion: potential to interbreed, weakness: doesn"t work for, also many sexual organisms, fossils, species without sexual reproduction. Lack of knowledge about their ability to mate with different kinds of organisms. Morphological species concept: criterion: similarity of appearance, weakness: Strength: easy and objective similar looking things can be different species. Different looking things can be the same species. Why are species discrete: reproductive isolating mechanisms. Prevents populations belonging to different species from interbreeding, even if their ranges overlap. Prezygotic barriers: habitat, time, behavior, mechanical, gametic. Postzygotic barriers: reduced hybrid viability, reduced hybrid fertility, hybrid breakdown. Speciation can occur in 2 ways (1) allopatric speciation (2) sympatric specieation. In sympatric speciation, speciation takes place in geographically overlapping populations: gene flow may be reduced by:
