March 3rd - Excluded organism-clonal parthenogenetic highly self-fertile species-syngameans cluster of species hybridization Cladogenesis-occurs

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3/3/09 Micro-macro evolution -origin of species -specialization is endpoint -Neo Darwinian Synthesis Haldane -really can’t define species Mayr -species are actually or potentially interbreeding natural populations which reproduce in isolation from other groups -can’t have divergence if you have gene flow; so they stay together Biological Species Concept -speciation=development of barriers to reproduction (are reproductively isolated from one another) -prezygotic isolation (small) -crosses between species prevented 1. potential mates meet but do not mate (ethological differences) 2. potential mates do not meet (seasonal) Ex. Flowering times or habitat differences, pollinator preference 3. copulation pollination, but no fertilization (mechanical isolation, pollen/stigma incompatibility) Post-mating -not exact boundaries -egg fertilized but dies -F1 hybrids have reduced viability (low hybrid viability) -F1 hybrids have reduced fertility (hybrid sterility) -highlights importance of reproductive isolation
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Unformatted text preview: Excluded organism-clonal, parthenogenetic, highly self-fertile species-syngameans cluster of species hybridization Cladogenesis-occurs when you have divergence of two genetic lineages froma common ancestor-complete when the evolutionary lineage becomes two species Geographic-allopatric- species form from geographically isolated populations-birds on island separate from each other-parapatric- species form from adjacent populations due to species gradient-sympatric- species form from geographically overlapping populations Allopatric model-Genetic modes of speciation-chromosomal rearrangements arise that lead to reproductive isolation through hybrid sterility-structural rearrangements-polyploidy instantaneous and sympatric mode of speciation-increase in single haploid set-can’t find a plant without polyploidy Autopolyploid-occurs within single evolutionary Allopolyploidy-different lineages that form-an increase in progenes through evolution...
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This note was uploaded on 05/04/2009 for the course GENE GENE3000 taught by Professor Anderson during the Spring '09 term at University of Georgia Athens.

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March 3rd - Excluded organism-clonal parthenogenetic highly self-fertile species-syngameans cluster of species hybridization Cladogenesis-occurs

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