Lecture 20 - Lecture 20: Feb. 20 Evolutionary Processes:...

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1 Lecture 20: Feb. 20 Evolutionary Processes: Genetic Drift, Gene Flow & Mutation Genetic Drift - lab & field studies - founder effects - genetic bottlenecks Gene Flow Mutation - DNA replication, protein synthesis & types of mutations - Neutral model of molecular evolution - role of mutation in evolution Multiple Processes Can Interact in Natural Populations Discussion Activity this Week Article on Sexual Selection (week 8 folder) Complete essay due by Feb. 22 Exam 2: Monday, March 3 Covers lectures 12-22 Optional Review Session on Sun., March 2, 7 to 9pm Nat. Sci. Aud. Check Qwizdom Points on SAMS https://cats.lsa.umich.edu/ Chapter 24 : 527-533 Evolutionary Processes 9 natural selection, 9 sexual selection, genetic drift, gene flow, These are the processes that lead to changes in the genetic makeup of a population. Methods: - 96 vials started with 4 males and 4 females - one gene for bristle shape: 2 alleles, straight & bent - started with equal frequencies of each allele females at random - no selection, no migration, mutation rate low Genetic Drift Results: after 16 generations, 29 vials – bent freq. = 1 41 vials – straight freq. = 1 26 vials – both alleles present ~ in 73% of populations, drift had reduced genetic diversity Wright’s Lab Experiment on Fruit Flies random (unpredictable) changes in allele or genotype frequencies in a population of individuals results from chance events (sampling error), not from heritable traits drift affects all populations, but is a more powerful force in small populations tends to reduce levels of genetic diversity leads to random fixation or loss of alleles Genetic Drift
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This note was uploaded on 12/06/2009 for the course BIO 225 taught by Professor Pavgi during the Spring '08 term at University of Michigan.

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Lecture 20 - Lecture 20: Feb. 20 Evolutionary Processes:...

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