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Adaptive (advatageous)
Certian triats that result in greater reproductive success in particular environment.
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Allele
Each member of a gene pair or group.
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Balancing Slection
When a heterozygous combination of alles (genes) is positively fovored.
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Maladaptive (dissavantageous)
Certain traits that will genreally decline in frequency or even dissaear eventually.
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Cline
The variation of frequency from one end of the region to the other.
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Crossing-over
The exchange sections the pair of homologus chromosomes in meiosis during seperation.
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Directional Selection
Increases the frequency of a trait (the trait is positively fovored and average value shifts over time toward the adaptive trait)
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Natural Selection
The main process that increases the frequency of adaptive traits through time, which involves 3 conditions: variation, heritability, an ddifferential reproductive success.
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Normalizing Selection
Average value does not change, but natural selection removes the extremes.
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Segregation
One cause of shufflig or sorting of chromosomes in meiosis, where an individual could get any of the possible assortments of paternal and maternal chromosomes.
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Sources of variability in natural selection (5)
- Genetics: Genetics rcombination and mutation
- Processes: Gene flow and Genetic drift
- Potential surce: Hybirdization
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Mutation
Change in the DNA sequence.
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Genetic Drift (Wright Effect)
Various random processes that affect gene frequencies in small, relatively isolated populations. Two variety of genetic drifts are founder and bottleneck effect.
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Gene Flow
The process whereby genes pass from one population to another through mating and reproduction.
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Species
A population that conssits of organisms able to interbreed and produce fertile and viable offspring.
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Hybridization
The creation of a vible ofspring from two different species.
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Speciation
The development of a new species, may occur if one subgroup of a species finds itself in radically different environment and undergo enough gentic changes to prevent the two population from interbreeding.
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Gradualism
Traits frequencies change only gradually over time.
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Punctuated equilibrium
New species involve quickly; but once a sucessful species emerges; its characteristics are likely to change very little over a long periods of time.
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