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Unformatted text preview: 2. Allele frequencies in a population can change if evolutionary forces, such as mutation, migration, nonrandom mating, genetic drift, and natural selection, act on the population. 3. Natural selection acts only on phenotype, not on genotype. 4. Natural selection reduces the frequency of a harmful recessive allele slowly; very few individuals are homozygous recessive, so very few express the allele. 5. The range of phenotypes that are controlled by polygeneric traits result in a normal distribution when plotted on a graph. 6. Directional selection results in the range of phenotypes shifting toward one extreme. 7. Stabilizing selection results in the range of phenotypes narrowing. | P a g e Gautham 2/16/2010...
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- Spring '09