lecture_25__05 - Types of reproductive barriers between...

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Types of reproductive barriers between species:
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prezygotic barriers : barriers to mating that occur prior to fertilization habitat isolation different habitats within the same geographical area example: different depth in the ocean/soil different tissues on the same host temporal isolation different breeding seasons different circadian rhythms behavioral isolation different mating rituals (exclusive to each species) different mating-related visual signals (appearance) different mating-related olfactory signals ,etc.
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prezygotic barriers (continued) mechanical isolation different anatomies Aquilegia formosa North American columbine species, fertilized via hummingbirds Aquilegia chrysantha North American columbine species, fertilized by butterflies, flowers too long to be fertilized via hummingbirds gametic isolation external vs. internal fertilization differences in sperm survival in different environments incompatibility in mechanisms of sperm entry into oocytes
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postzygotic barriers : barriers to mating that occur after fertilization reduced hybrid viability genetic differences between gamete genomes, leading to failure during development or weakness during life these 2 butterfly species are found in mostly separate but overlapping locations. They are capable of interbreeding but the coloring of the hybrid offspring is selected against in the wild. Heliconius himera Heliconius. erato reduced hybrid fertility genetic differences between gamete genomes, leading to loss of fertility in hybrid offspring hybrid breakdown
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This document was uploaded on 09/06/2009.

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lecture_25__05 - Types of reproductive barriers between...

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