Study Zone- Populations

Study Zone- Populations - 2. Allele frequencies in a...

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Populations – Study Zone (Pg. 333) Key Concepts | How Populations Grow 1. A population consists of all the individuals of a species that live together in one place at one time. 2. A population s future survival is determined by its size, density, and dispersion. 3. Though a population's growth is limited by factors such as pi edation and availability of resources, a population can grow rapidly and may eventually stabilize at a size that the environment can sustain. 4. Some populations grow quickly in response to density-independent factors, and other populations grow more slowly and their size is controlled by density- dependent factors. | How Populations Evolve 1. The Hardy-Weinberg principle states that the frequencies of alleles and genotypes remain constant in populations in which evolutionary forces are absent.
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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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