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15 Cards in this Set
- Front
- Back
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speciation
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-splitting event that creates two or more distinct species from a single ancestral group
-allele frequencies change independently over time, populations become distince species -outcome of isolation and divergence |
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isolation
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-reduction of gene flow
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divergence
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-when mutation, genetic drift, and selection act on a populations separately
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biological species concept
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-reproductive isolation: pre-mating barriers and post-mating barriers
-don't breed or produce viable offspring disadvantage: not applicable to asexual or fossil species; difficult to assess if species do not overlap geographically |
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pre-mating barriers
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-habitat (allopatry)
-phenological (timing of cycles) -behavioral -gametic -mechanical |
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post-mating barriers
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-hybrid inviability
-hybrid sterility |
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morphospecies concept
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-populations are morphologically distinct
disadvantages: subjective |
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phylogenetic species concept
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-smallest monophyletic group on evolutionary tree
disadvantages: few well-estimated phylogenies are currently available |
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allopatric speciation
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-speciation that begins with physical isolation via either dispersal or vicariance
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dispersal and colonization
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-part of population migrates to new isolated habitat
-founder effect (non-representative allele frequs in new pop) -natural selection Ex. Galapagos finches |
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vicariance
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-new physical barrier splits the geographic range of species
ex. ratites on Gondwana |
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sympatric speciation
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-speciation that occurs without physical isolation
-sympatric populations are not physically isolated, but may be isolated by preferences for different habitats ex. soapberry bugs |
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polyploidy
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-doubling of the chromosome number
-this reduces gene flow btwn mutant and normal (wild-type) individuals -mutant and normal individuals are isolated in that they produce odd-ploidy individuals that are largely infertile -can result in speciation especially for plants |
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autopolyploid
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-polyploidy within species due to error in meiosis or mitosis
ex. maidenhair fern |
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allopolyploid
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-polyploidy as a result of different species maing
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