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Unformatted text preview: 2/17/10 1 287 287 Speciation •What are species? •What is the geography of speciation? •Why do some groups speciate more than others? •What is the genetics of speciation? •What is the time scale of speciation? 288 288 Speciation •What are species? •The biological species concept (BSC) •Groups of actually of potentially interbreeding populations, which are reproductively isolated from other such groups • Gene Fow (reproductive isolation) rather than phenotypic differences •Cryptic species - isolated but with little phenotypic differentiation •Problems with BSC •Asexuals •Extinct groups •Gene Fow between “good” species •Breeding experiments impractical 2/17/10 2 289 289 Speciation •What are species? •The phylogenetic species concept •Two populations are species if they are diagnosably different (morphology, DNA) •Other species concepts •Evolutionary •Phylogenetic/Genealogical •Recognition/cohesion •Phenetic •The search for a single species concept that applies unambiguously and in all situations is doomed to fail. EVOLUTION IS A PROCESS, so we should expect intermediate stages and fuzzy boundaries....
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- Winter '10
- Evolution, Ridley, • Prezygotic isolation