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27 Cards in this Set
- Front
- Back
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biological species concept
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able to breed with one another to produce fertile offspring
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reproductive isolating mechanisms
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prevent interbreeding b/t 2 diffrent species whose ranges overlap. gene flow is prevented
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prezygotic barriers
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reproductive isolating mechanisms that prevent fertilization
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5 types of prezygotic barriers
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-temporal
-habitat -behavioral -mechanical -gametical |
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temporal isolation
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similar species mate @ diffrent times
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habitat isolation
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similar species mate in diffrent habitats
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behavioral isolation
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similar species have diffrent courtship behaviors
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gametic isolation
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gametes in similar species are chemically incompatible
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postzygotic barriers
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fertilization occurs however these barriers increase the likelihood of reproductive failure
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3 types of postzygotic barriers
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hybrid inviability
hybrid sterility hybrid breakdown |
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hybrid inviability
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interspecific hybrid dies at the embryonic stage.
genes from parents don't interact properly for normal development |
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hybrid sterility
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interspecific hybrid survives but is sterile.
2 causes: (1) hybrid animals may exhibit courtship incompatible with those of parental species (2) gametes are abnormal in meiosis (can't pair properly in prophase) |
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hybrid breakdown
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offspring of interspecific hybrid are unable to reproduce
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speciation
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evolution of new species
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2 ways of speciation occuring
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allopatrick and sympatrick
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allopatric speciation
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1 pop becomes geographically seperated and evolves by natural selection and/or genetic drift
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sympatric speciation
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new species evolves within the same geographical area. this occurs when reproductive isolating mechanisms evolve at the start of speciation
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allopolyploidy
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contains multiple sets of chromosomes from 2 or more species
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hybridization
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sexual reprodction b/t individuals from closely related species
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allopolyploids
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can self-fertilize or find likes of themselves
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2 models of evolutionary rate
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punctuated equilibrium
gradualism |
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punctuated equilibrium
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suggests that fossil record actually reflects evolution
long periods of stasis (little or no evolutionary change) are punctuated or interrupted by short periods of rapid speciation, triggered by environment. speciation proceeds in spurts |
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gradualism
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evolution proceeds continously over long periods. rarely observed in fossil record b/c record is incomplete
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macroevolution
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large-scale phenotypic changes in populations
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adaptive radiation
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evolutionary diversification. "divergent evolution"
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adaptive zones
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ecological areas on the islands that were not already occupied by other pop. which brings about competition
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extinciton
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last member of species dies. frees adaptive zones.
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