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18 Cards in this Set
- Front
- Back
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hybridization
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mating between members of distinct species
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prezygotic barrier
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a barrier to reproduction that prevents mating, prior to forming zygote
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reinforcement
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barriers between related species are strengthened when hybrids have reduced fitness
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root
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the bottom/basal/most ancient node on a phylogenetic tree
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phylogenetic tree
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an estimate of the evolutionary history and patterns of relatedness within a group
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branch
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part of a phylogenetic tree showing pops/lineages through time
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outgroup
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a group that diverged prior to the other taxa in the study; can be used to root a tree
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node
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point in a tree where an ancestral gourp diverges into 2 or more descendant groups
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polytomy
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node with >2 descendant groups
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sister taxa
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occupy adjacent brances on a tree
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synapomorphy
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a homologous trait shared among certain species, similar because it was modified in a common ancestor. these traits identify monophyletic groups!
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parsimony
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the most likely explanation is the one that implies the smallest number of changes
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adaptive radiation
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divergence of a clade into population adapted to many ecological niches
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polyploidy
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duplication of a genome above the normal ploidy level
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autopolyploidy
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polyploidy that results from byridization of different species and failure of meiosis in hybrid offspring
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sympatric speciation
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speciation that does not involve geographic separation or a physical barrier to gene flow, but that results from reproductive isolation despite physical proximity
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background extinction rate
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the rate at which species go extinct outside of the periods identified as mass extinctions. Best estimated at 1 spp per million spp per year (which would equal 10-100 spp per year at current diversity levels)
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mass extinction
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a period in which extinction is significantly elevated above background rates; defined by some as >60% of spp going extinct within 1 million years
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