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23 Cards in this Set
- Front
- Back
Speciation |
process by which one species splits into 2+ species |
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Microevolution |
evolutionary change below the species level; change in allele frequencies in a population over generations |
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Macroevolution |
evolutionary change above the species level |
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Species |
group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but do not produce viable, fertile offspring with members of other such groups |
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Reproductive Isolation |
existence of biological factors that impede members of two species from producing viable, fertile offspring |
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Hybrid |
offspring that results from mating of individuals from two different species or from two true-breeding varieties of the same species |
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Describe the five prezygotic barriers that prevent inter-species mating. |
1. Habitat isolation - living in different parts of the same ecosystem 2. Temporal isolation - mating at different times (seasonal, diurnal/nocturnal, etc) 3. Behavioral isolation - courtship rituals are specific to each species 4. Mechanical isolation - mating may be attempted by the pieces don't line up 5. Gametic isolation - sperm from one species may not be able to fertilize the egg from another (unable to penetrate membrane, unable to survive, etc) |
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Describe the three postzygotic barriers that prevent inter-species mating. |
1. Reduced hybrid viability - genes interact in ways that impair the hybrid's development 2. Reduced hybrid fertility - most hybrids are sterile due to failure in meiosis 3. Hybrid breakdown - breeding of hybrid to parent species lead to frail/sterile second generation hybrids |
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Biological Species Concept |
concept that species are defined by what they can breed with to produce viable, fertile offspring |
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Morphological Species Concept |
concept that species are defined by body shape and other structural features |
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Ecological Species Concept |
concept that defines species in terms of its ecological niche, the sum of how members of the species interact with nonliving and living parts of their environment |
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Phylogenic Species Concept |
concept that defines species as the smallest group of individuals that share a common ancestor, forming on brance on the tree of life |
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Allopatric Speciation |
formation of new species in populations that are geographically isolated from one another |
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Sympatric Speciation |
formation of a new species in populations that are not geographically isolated from one another |
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The formation of new species in geographically isolated populations is called _____________ speciation. |
The formation of new species in geographically isolated populations is called allopatric speciation. |
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The formation of new species in non-geographically isolated populations is called _____________ speciation. |
The formation of new species in non-geographically isolated populations is called sympatric speciation. |
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Polyploidy |
chromosomal alteration that results in an organism having more than two complete chromosome sens (3n, 4n, etc.) as a result of accidents in meiosis or mitosis |
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Autopolyploid |
individual with more than two chromosome sets all derived from a single species |
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Allopolyploid |
fertile individual with more than two chromosome sets derived from two different species interbreeding and combining their chromosomes |
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Hybrid Zone |
geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry |
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Describe the three possible outcomes for a hybrid zone. |
1. Reinforcement - reproductive barriers strengthen and the hybrids gradually disappear 2. Fusion - reproductive barriers weaken and the two species fuse to form one 3. Stability - reproductive barriers remain constant and hybrids continue to be created |
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Punctuated Equilibria |
in the fossil record, long periods of apparent stasis, in which a species undergoes little or no morphological change, interupted by relatively brief periods of sudden change |
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Adaptive Radiation |
rapid speciation under conditions in which there is little competition |