092007_EvolutionaryMechanisms3

092007_EvolutionaryMechanisms3 - 9/20/2007 Intro to...

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9/20/2007 1 Intro to Organismal Biology 9/20/07 Announcements 2 1. Biology Department Survey Go to“External Links” on Blackboard Today’s class Evolutionary mechanisms continued: 1. Genetic drift (chance effects due to small pop. size) 2. Gene flow (migration) 3. Mutation (generating new variation) 4. Nonrandom mating 5. Natural selection (Relevant reading: Ch. 23, 51 pp.1129-1130) 3 Gene flow 4 Evolutionary Mechanisms Gene flow Population may gain or lose alleles Results from movement of fertile individuals (e.g., migration) or gametes (e.g., long- distance pollination) 5 Evolutionary mechanisms Mutation The only way to generate NEW alleles Mutation rates lower in plants & animals compared to bacteria and viruses. Only mutations in germ cells are passed to offspring. 6
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9/20/2007 2 Evolutionary mechanisms: Mutation 1. Example: Point mutation e.g., AAATCGCCCG copied as: AAATCGCCC C Consequences? Could be harmless:
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092007_EvolutionaryMechanisms3 - 9/20/2007 Intro to...

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