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Three mechanisms that can cause allele frequency change
1. natural selection
2. genetic drift
3. gene flow
differences between gene pools of separate populations or populations subgroups (some karyotypes are different, but their phenotypes are the same) (chance events)
geographic variation; graded change in a trait along a geographic axis; result of natural selection
five conditions for hardy-weinberg
1. no mutations
2. random mating
3. no natural selection
4. extremely large population size
5. no gene flow
(can evolve at some loci while being in hardy-weinberg equilibrium at other loci)
allele frequencies fluctuate unpredictably from one generation to the next; the smaller sample the greater the chance of deviation from predicted results; reduce genetic variation through losses of alleles
the founder effect
a few individuals become isolated from a larger population; allele frequencies in the small founder population can be different from those in the larger parent population
a sudden reduction in population size due to a change in the environment; resulting gene pool may no longer be reflective of the original population's gene pool
effects of genetic drift
1. significant in small populations
2. causes allele frequencies to change at random
3. can lead to a loss of genetic variation within populations
4. dan cause harmful alleles to become fixed.
movement of alleles among populations; can be transferred through the movement of fertile individuals or gametes; reduces differences between populations over time; more likely than mutation to alter allele frequencies directly; decreases and increases the fitness
the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals
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