Term
| What are the two methods of increasing genetic variation in populations? |
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Definition
1. Heterozygote advantage
2. Frequency dependent selection |
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Term
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Definition
| When heterozygotes maintain higher fitness than either homozygous genotypes. |
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Term
| Frequency dependent selection |
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Definition
| When the fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population. |
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Term
| Negative frequency dependence |
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Definition
| Fitness is higher when frequency is low |
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Term
| Positive frequency dependence |
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Definition
| Fitness is higher when frequency is high |
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Term
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Definition
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Term
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Definition
| Standard for assessing whether individuals belong to the same species or not |
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Term
| Morphological species concept |
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Definition
| Individuals of the same species have characteristics that make them more morphologically similar to each other. Proposed by Linneaus. |
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Term
| What are the pros and cons of using the morphological species concept? |
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Definition
Pros: Intuitive, widely applicable, works for extinct species
Cons: Not based on any one theory, subjective |
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Term
| Biological species concept |
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Definition
| Organisms of the same species are groups of actually or potentially interbreeding natural populations. Proposed by Ernst Mayr. |
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Term
| What are the pros and cons of using the biological species concept? |
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Definition
Pros: criterion clearly identified, testable, based on theory
Cons: lack of historical dimension (cannot be used for extinct species), doesn't work for hybrids |
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Term
| Phylogenetic (Lineage) species concept |
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Definition
| Diagnosable cluster of individual organisms within which there is a pattern of ancestry and descent. |
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Term
| What are the pros and cons of using the phylogenetic species concept? |
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Definition
Pros: works for all organisms (extinct or not), consistent with evolutionary theory
Cons: not clear how species are deemed "different" from one another, doesn't explain hybridization |
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