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Unformatted text preview: BioEE 278 Spring 2007 Evolutionary Biology Lecture 14 NATURAL SELECTION ON SIMPLE TRAITS Reading: Ch. 12, pp. 270- top of 282 (Look at Box 2A up to section 1, dont memorize!); pp. 283- 284- top of 287 A. Reminder Hardy Weinberg model & natural selection 1. When does evolution by natural selection? a. consistent differences in fitness or reproductive success among phenotypes b. natural selection occurs IF (1) phenotypic variation phenotypic variation is heritable 2. Natural selection is inevitable. a. nothing more than differential survival and reproductive success b. does not have a goal or a purpose c. does NOT anticipate the future d. in general, the average success of individuals increases over time. It is not always the case that the best genotype increases and the best allele becomes fixed (see heterozygote disadvantage) 3. Questions. a. what happens to alleles frequencies with natural selection? b. is genetic variation maintained? B. Population genetic model of natural selection 1. Fitness and reproductive success....
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- Fall '07