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18 Cards in this Set
- Front
- Back
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How does the biological species concept define species?
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As a group of interbreeding organisms that are reproductively isolated from other organisms
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How does the biological species concept say that differences are maintained between species?
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Through gene flow
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Define gene flow.
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The movement of genetic material within parts of a population or from one population to another. Tends to maintain similarities among members of the same species
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How does the ecological species concept define species?
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Emphasizes the role of selection in maintaining species boundaries.
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Define allopatric speciation.
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Speciation fostered by geographic or environmental barriers that isolate part of a population
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What two processes may increase the degree of reproductive isolation after two new species created by allopatric speciation come back into contact?
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Character displacement and reinforcement.
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Define character displacement.
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The result of competition between two species that causes the members of different species to become morphologically distinct from each other.
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Define reinforcement.
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The process in which selection acts against the likelihood of hybrids occurring between members of two phenotypically distinctive populations, leading to the evolution of mechanisms that prevent interbreeding.
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Define parapatric speciation.
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Holds that selection alone is not sufficent to produce a new species, but new species can be formed if selection is combined with partial genetic isolation.
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Define sympatric speciation.
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Strong selelction favoring different phenotypes can lead to speciation even when there is no geographic separation, and therefore initially there is extensive gene flow among individuals in the population.
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Define phylogeny.
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The evolutionary relationships among a group of species, usually diagrammed as a family tree.
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What are the three main reasons for reconstructing phylogenies?
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1) Basis for identification and classification of organisms.
2) Helps explain why a species evolved certain adaptions and not others. 3) Can deduce the morphological features of behaviors by comparing the traits of different species. |
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Define systematics.
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The construction of phylogenies
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Define analogous.
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Similarity between traits that is due to convergent evolution, not common descent.
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Define homologous.
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Similarity between traits that is due to common ancestry, not convergence.
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Define ancestral trait.
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One that characterized the common ancestor of multiple species.
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Define derived traits.
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Traits that have evolved since the time of the last common ancestor of the species
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How do systematists distinguish ancestral from derived characters?
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Ancestral characters:
1) Appear earlier in organismal development 2) Appear earlier in the fossil record 3) Are seen in out-groups |
