Genetic Drift

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Genetic Drift Evolution

• APES

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Gene Pools

• Genetic Drift is the change in a gene pool due to
  chance.
• There are 2 examples
• Bottleneck effect
• Founder effect

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1) Bottleneck Effect

• Reduce the size of a population randomly
• Natural disasters
• Ex fire, earthquake, flood
• Results in the loss of genetic variation
• Smaller population
• Not representative of the original one
• Certain alleles may be over or underrepresented

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1) Bottleneck Effect Tay-Sachs

• High rate among Eastern European Jews
• Attributed to population bottleneck in Middle
  Ages
• Population was dramatically reduced at this time
• Individuals who remained alive reproduced just
  happened to be ones who carried Tay-Sachs

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2) The Founder Effect

• When a small population breaks away from a larger
  one
• Colonize a new area
• Extreme isolation intermarriage leads to high
  frequencies of specific traits

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Natural Selection

• Remember that natural selection is the major
  mechanism of evolution in any population.
• Survival of the Fittest

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Any Questions?