CAS BI 309 Lecture Notes - Lecture 16: Pleiotropy, Gene Expression, Sahelanthropus
30 Mar 2018
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Morphology (visual characteristics, not always accurate, fossil record lacks certain differeniating traits (sound, skin, etc) Phylogenetically (common ancestor; testable in extant species) Reproductive isolation (inability to produce fertile offspring; limiting bc some species are able to interbreed) Mayr: groups of interbreeding natural populations that are r eproductively isolated from other groups; species are real. Species reduced definition: evolutionary distinct lineages as recognized by multiple criteria. As lineages, new species arise via divergence or extinction of intermediates. Mayr"s speciation: (1) geographical isolation, (2) small populations/ founder effects, (3) genetic incompatibilities. Geographic models of speciation (highlight significance between drift vs. selection): Sympatric: within single area (basically no obvious geographic isolation) Divergence due to drift : hard to test, applies only to populations isolated by distance. Drift may play a role in speciation (limited evidence) = i. e. founder effect speciation may be rare bateson-dobzhansky-muller model. Evidence for role of adaptive divergence in speciation.
