Chapter 26 - Chapter 26 Speciation If gene flow ends allele...

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Chapter 26: Speciation Species, how are they id’ed The biological species concept Mechanisms of reproductive isolation The morphospecies concept Phylogenic species concept If gene flow ends, allele frequencies in isolated populations are free to diverge- mening the populations begin to evolve independently of each other. If mutation, selection, and genetic drift cause isolated populations to diverge sufficiently, distinct types or species, form, speciation takes place Speciation is a splitting event that creates two or more distinct species form a single ancestral group. When complete, a new branch has been added to the tree of life Species- defined as an evolutionarily independent population or group of populations 3 criteria: (1) the biological species concept (2) the morphospecies concept (3) phylogenetic species concept the critical criterion for id’ing species is reproductive isolation; no gene flow can occur between the populations that are reproductively isolated from each other. If two populations do not interbreed, they fail to produce viable and fertile offspring, then they are considerd to be two distinct species (tiger+ lion = liger) Reproductively isolated populations are evolutionary independent Prezygotic isolation prevents individuals of
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This note was uploaded on 03/21/2012 for the course BIOSC 160 taught by Professor Coffman during the Spring '10 term at Pittsburgh.

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Chapter 26 - Chapter 26 Speciation If gene flow ends allele...

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