BSC 2010 Lecture Notes - Lecture 30: Allopatric Speciation, Macroevolution, Ploidy
17 Nov 2015
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Bsc 2010 lecture 30 macroevolution 1: origin of species: macroevolution, the formation of species. A species is a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups. Problems with definition of species: does not apply to asexual organisms, cannot be applied to fossils. Potentially interbreeding is ill-defined, particularly in the case of hybrids. How do species form: allopatric speciation, literally other country , geographic barrier divides population or part of population crosses barrier and founds new population, geographic barrier divides population. Populations differentiate: most prevalent form of speciation, sympatric speciation, literally same country , species arise from a connected population, common in plants, occasional in animals, generally two types: polyploidy, behavioral change, speciation by polyploidy. New individual is viable but genetically isolated. In plants, individual with new ploidy-level can often self-fertilize: speciation by behavioral change. Young return to new place to mate. No gene flow with original population: reproductive barriers between species.
