Lecture22bio

Lecture22bio - BIOLOGY 1001 Wednesday, April 9, 2008...

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Wednesday, April 9, 2008 Lecture 22 Sympatric Speciation Sympatric Speciation: Polyploidy Polyploidy Having more than two homologous chromosomes of each type. o Diploid: 2 Homologues o Triploid: 3 Homologues o Tetraploid: 4 Homologues Instant Speciation by Polyploidy Figure 16-5 Adaptive Radiation Rise of many new species in a relatively short time from one species invading different habitats. o E.g., Hawaiian Islands, Galapagos, Cichlids. Reproductive Isolating Mechanisms Prevent pollination or mating. Block fertilization or embryonic development. Cause offspring to be weak or sterile. Premating isolation mechanisms o Prevents organisms of two populations from mating. Postmating isolation mechanisms o Prevents organisms of two populations from producing vigorous, fertile offspring after mating. Premating Isolating Mechanisms 1.) Geographical Isolation - Geographical barrier prevents mating. -
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Lecture22bio - BIOLOGY 1001 Wednesday, April 9, 2008...

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