lecture_14_speciation_SW_updated

lecture_14_speciation_SW_updated - What Causes Reproductive...

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What Causes Reproductive Isolation: Stages of Reproduction Finding a mate/mating Fertilization Zygote Adult reproduction
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‘Paradox’ of Speciation: Low fitness of Hybrids 1) With premating isolation, disruptive natural selection alone can PREVENT formation of hybrids- speciation is a side effect of adaptation 2) Postmating, prezygotic barriers can similarly be driven by natural selection 3) Extrinsic postzygotic isolation can be actively maintained by natural selection
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Intrinsic Postzygotic Isolation: Inherent Genetic Problems with Hybrids Species A X Species B F1 X F1 F2 Sterility/lethality
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‘Paradox’ of Speciation: Low fitness of Hybrids -Paradox most problematic for intrinsic postzygotic isolation, which seems unconditionally harmful
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1) Gene interactions (epistasis) between species -Dobzhansky-Muller incompatibilities 2) Meiotic problems due to chromosome changes -chromosome rearrangements -polyploidy
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This note was uploaded on 04/22/2009 for the course EEB 318 taught by Professor Cutter during the Spring '09 term at University of Toronto.

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lecture_14_speciation_SW_updated - What Causes Reproductive...

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