Synthesis Notes

2pqq2 what is directional selection one allele is

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Unformatted text preview: shit with it. Like frequencies of alleles or genotypes in a population  ­ Random Mating—Genotype frequencies give by allele frequencies—no change in genotype frequencies.  ­ In no differential selection, no mutation, no migration, infinite population size— no change in allele frequencies across generations What are its assumptions?  ­ Random Mating  ­ No Differential Survival  ­ No Mutation  ­ No Migration  ­ Infinite Population Size How do we calculate expected genotype frequencies under H ­W EQ? 9 Example: 10 How can we calculate expected ratios of carriers to phenotypically recessive individuals? 2pq:q2 What is directional selection?  ­ One allele is consistently favored over another  ­ A process of selection in which selection drives phenotype in a single direction, or in which selection drives allele frequencies in a single direction toward fixation of a favored allele What makes the increase in frequency of a particular allele faster or slower?  ­ Strong selection for an allele will be more frequent (faster)  ­ Recessive traits have a hard time in populations so are slower… poor thing What is overdominance?  ­ a form of frequency ­independent selection in which heterozygote genotypes have higher fitness than the corresponding homozygote genotypes. They meet at some equilibrium point (reaches an intermediate frequency). Balanced Polymorphism  ­ example: Sickle Cell and Malaria 11 What is underdominance?  ­ a form of frequency ­independent selection in which the heterozygote genotype has a lower fitness than either corresponding homozygote genotype (get rid of polymorphism and pushes to the extremes)  ­ Unstable Equilibrium What are positive and negative frequency dependent selection?  ­ Frequency ­dependent selection is the term given to an evolutionary pro...
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This note was uploaded on 05/18/2013 for the course BIOL 3040 taught by Professor Staff during the Spring '08 term at LSU.

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