BIOL 123 Lecture Notes - Lecture 24: Allopatric Speciation, Apolipoprotein B, Speciation
Document Summary
Models can help generate hypotheses about real pop. Speciation is a continuum from minor reproductive isolation to full blown separation. Today agree that speciation in sympatry is possible = based on theoretical models on population genetics although process is more complex than speciation in allopatry. Polar bears: a tale of ecological speciation and interspecies gene flow. Closest relative is the brown bear = encircle range of polar bear. Rapid divergence in ecological traits for hunting. Polar bears experience stronger selection than brown bears. Apob gene protein binds cholesterol: polar bears able to cope with diet. Pigmentation gene = white = blend in. Gradual first weak only reducing gene flow, eventually become strong and choke off gene flow. How long does it take reproductive barriers to lead to new species: can take several hundred thousand years to become isolated enough to be considered a species of their own, or it can take generation(s)
