Bio 201 F08 True lect 5v3r

Bio 201 F08 True lect 5v3r - Modes of Speciation Allopatric...

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Modes of Speciation Allopatric speciation geographical isolation Reproductive isolation as a “by product” Sympatric speciation – No geographic isolation – Two types of examples Polyploidy in plants • “instant speciation” Ecological • Divergent natural selection in same geographic region
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What do I mean by by product ? (a hypothetical example) Original species/population range Range becomes split by a river; NO movement between 2 populations A million years go by; the river dries up; two populations come back into contact. X
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Modes of Speciation Allopatric speciation geographical isolation Reproductive isolation as a “by product” Sympatric speciation – No geographic isolation – Two types of examples Polyploidy in plants • “instant speciation” Ecological • Divergent natural selection in same geographic region
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Sympatric speciation: polyploidy
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Sympatric speciation: polyploidy Tragopogon pratensis (salsify)
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Sympatric speciation – Divergent selection in adjacent “microhabitats” (e.g. different plant hosts) • e.g. the apple maggot fly Rhagoletis pomonella Native host in N. America: hawthorne Apples introduced in N. America in 1600s. In the last ~300 years, a distinct “host- race” utilizing apples has evolved. Rhagoletis pomonella
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Evolutionary divergence of several species descended from a common ancestor into a variety of different *adaptive forms. *Usually with reference to diversification
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Bio 201 F08 True lect 5v3r - Modes of Speciation Allopatric...

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