Notes genetic drift

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Notes genetic drift

  1. 1. Notes: Genetic Drift (pg 10)• Genetic Drift = Change in allele frequencies ina population due to chance events
  2. 2. Notes: Genetic Drift (pg 10)• Genetic Drift = Change in allele frequencies ina population due to chance events• More likely to occur in small populations
  3. 3. Notes: Genetic Drift (pg 10)• Genetic Drift = Change in allele frequencies ina population due to chance events• More likely to occur in small populations• Unlike natural selection, which favorsbeneficial traits, genetic drift is random andcan cause an increase in traits that arebeneficial, detrimental, or neutral
  4. 4. Types of Genetic Drift1. Founder effect: Changes in gene frequencydue to colonization of a new area by a limitednumber of individuals
  5. 5. Types of Genetic Drift1. Founder effect: Changes in gene frequencydue to colonization of a new area by a limitednumber of individualsExample: British colony on Tristan da Cunhaisland founded by 15 people. 1 colonistcarried an allele for a type of blindness.Today, 2% of individuals on the island areblind, compared to <0.01% in the generalpopulation
  6. 6. 2. Population bottleneck: Change in genefrequency caused by a drastic reduction in thesize of a population, usually due to a naturaldisaster.
  7. 7. 2. Population bottleneck: Change in genefrequency caused by a drastic reduction in thesize of a population, usually due to a naturaldisaster or huntingExample: Cheetahs. 2 Bottlenecks: 10,000 yearsago (ice age) and 1800’s (hunting). Nowcheetahs are very similar genetically, leadingto problems associated with inbreeding
  8. 8. Output activity (pg 11)Imagine that a massive earthquake kills allhumans on Earth except for President Obamaand Vice President Biden and their families(they were safely aboard Air Force One).These 9 people will now repopulate the Earth
  9. 9. Output activity (pg 11)Imagine that a massive earthquake kills allhumans on Earth except for President Obamaand Vice President Biden and their families(they were safely aboard air force one). These9 people will now repopulate the Earth1. Are these people a representative sample ofhuman genetic diversity? Explain.2.List at least 5genetic traits that would be lostdue to this population bottleneck

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