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15 Cards in this Set
- Front
- Back
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define speciation
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origin/process of a new species
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who developed the biological species concept
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Ernst Mayr
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what is the biological species concept (BSC)
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species of a population or group of populations whose members have potential to interbreed in nature and produce viable, fertile offspring, and are reproductively isolated from other populations
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problems with BSC
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-asexual reproduction
-interbreeding of extinct species |
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define ecological species concept
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defines species in terms of ecological niche
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define genealogical species concept
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defines species as a set of organisms with unique genetic history
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define morphological species concept
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defines species in terms of its unique structural features
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describe two ways species become reproductively isolated
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-two populations become so different they are considered different species
-population becomes so different from ancestors they are considered different species |
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two patterns of speciation and give description
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anagenesis (phyletic): accumulation of changes (no increase in # of species)
cladogenesis (branching): branching of one or more new species (increases # of species) |
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how does allopatric speciation work
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1. population splits into two geographically isolated groups
2. genetic change accumulates 3. these differences prevent breeding btween these two populations 4. two species have evolved |
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describe sympatric speciation
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1. populations in same physical area
2. populations become genetically isolated by genetic events (polyploidy) |
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describe parapatric speciation
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-contiguous populations
-individuals more likely to mate with local neighbors |
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what 2 types of barriers exist in reproductive incompatibility btween species
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-prezygotic (before fertilization)
-postzygotic (after fertilization) |
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name 5 prezygotic barriers
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-habitat isolation: live in diff habitat, rarely meet
-behavioral isolation: species do not recognize signals/calls for mating -temporal isolation: breed at diff. times of year -mechanical isolation: anatomically incompatible -gametic isolation: gametes incompatible |
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name 3 postzygotic barriers
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-reduced hybrid viability: hybrid fails to develop
-reduced hybrid fertility: mostly/completely sterile -hybrid breakdown: offspring of hybrid have reduced viability/fertility |
