EvolutionMechanisms160-page3 - • In contrast isolated...

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Evolutionary Mechanisms - 3 Agents of Evolution: Factors that bring about change 1 . Mutation Inheritable changes in the DNA sequence Can be induced for study Original source for infinite numbers of small changes in genes Recombination Natural occurrence in meiosis so that no two gametes are identical 2 . Gene Flow or Migration Migration is the flow of genes from one population of a species to another population. This is also called gene flow. Dispersal to new geographical areas Fledging of young Transport of pollen, spores, etc. Gene flow also maintains a gene pool over larger geographical areas with nomadic patterns of travel. Gene flow usually decreases genetic differences between populations by routinely adding and removing individuals. Gene flow tends to keep populations of species from varying too much by continually "mixing" the alleles of the species.
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Unformatted text preview: • In contrast, isolated gene pools are important factors in speciation, since they minimize gene flow, and small populations are more subject to random events that limit the gene pool from one generation to the next. Genetic Drift and Small Populations Any population can be subject to rapid and random changes that can be caused by chance events. When a population is large, chance events are less likely to impact the gene frequency, although over generations they can. With small populations random events can have a much greater impact. Such random changes in gene frequencies are known as genetic drift. Characteristics of Genetic Drift • Rapid and random (chance) changes in gene frequencies of populations can result in a localized reduction in variation for that population. • More rapid when the gene pool is small and/or isolated...
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This note was uploaded on 12/29/2011 for the course BIO 151 taught by Professor Edwards during the Spring '10 term at SUNY Stony Brook.

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