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EvolutionMechanisms160-page2 - • Mutation does not occur...

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Evolutionary Mechanisms - 2 Genetic Equilibrium Formula Where: p = frequency of 1 st allele for gene (A) q = frequency of the 2 nd allele for gene (a) and: p + q = 1 Where: p 2 = homozygous (AA) q 2 = homozygous alternative (aa) 2pq = heterozygous (Aa) and: p 2 + 2 pq + q 2 = 1 The allele frequencies and genotype frequencies will be stable (genetic equilibrium) from generation to generation as shown by this equation. In an ideal population there would be genetic equilibrium (no change in gene frequencies), and no evolution would occur. Hardy and Weinberg then proposed the conditions that would be needed in a population to have genetic equilibrium: Population must be large enough to eliminate chance or random gene frequency fluctuations Population is isolated from other such populations (no immigration or emigration; no gene flow)
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Unformatted text preview: • Mutation does not occur, or if mutation occurs, forward and reverse mutations are equal, so the gene pool is not modified • Mating is random • All genotypes are equally viable; natural selection is absent Any change in gene frequency from generation to generation can then be documented and we can look for the reasons or agents responsible for the change. As a result of the Hardy-Weinberg Equilibrium, biologists could search for the "agents" of evolution, or those factors that result in the change of gene frequency. You can see why evolution is now defined in genetic terms, since it is a biological phenomenon of population genetics. Based on their work, there are five major causes or agents of change in populations:...
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