Evolution 5 - Main models of speciation Speciation models...

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1 Main models of speciation Speciation models Generic words for spatial distribution after speciation Caution: do not confuse!! Main models of speciation
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2 Also called “Geographic Sp” Break a population into multiple demes and usual evolutionary forces act… “Vicariance Model” of Allopatric Speciation
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3 Classic allopatry: “Tail” of two lizards Coastal Horny Lizard Phrynosoma coronatum Desert Horny Lizard Phrynosoma platyrhinos
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4 • Related by descent: – Homologous traits – Fossil ancestor Prior to 1.8 mya ONE SPECIES But then came drastic global cooling…
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5 Allopatric Speciation Critics sometimes call it “dumbell speciation”…
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6 Evolution tends to be faster in small demes • Chance can play a larger role (e.g. Founder’s Effect) • Inbreeding effects (expose “hidden” (expose hidden recessive alleles) • Effects of natural selection are not “diluted” by large numbers Peripatric speciation: think of Darwin’s finches
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7 Grant’s model: repeated peripatric speciation ( at each step, colonization by a small number)
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This note was uploaded on 11/08/2009 for the course HUMBIO 2A taught by Professor Boggs,c;durham,w during the Spring '08 term at Stanford.

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Evolution 5 - Main models of speciation Speciation models...

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