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Lecture 36

BIOL 1020 Lecture 36: Lecture 36

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Biological Sciences
BIOL 1020
Joy Stacey

Lecture 36 Natural selection, genetic drift, and gene flow can alter allele frequencies in population Three major factors alter allele frequencies and bring about most evolutionary change: o Natural selection o Genetic drift o Gene flow Natural selection Differential success in reproduction results in certain alleles being passed to the next generation in greater proportions while another set is passed on less frequently Genetic Drift The smaller a sample, the greater the chance of deviation from a predicted result Genetic drift describes how allele frequencies fluctuate unpredictably from one generation to the next o Not always environment imposing itself on the gene pool o Unpredictable change from one generation to the next due to chance Types of Drift Founder effect occurs when a few individuals become isolated from a larger population o By chance individuals that become isolated are of the same allele and then have different allele frequency Bottleneck effect is a sudden reduction in population size due to a change in environment o Eg. Tsunami by chance only certain alleles will be left and there will be a modification of allele frequency
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