lecture_notes_11_14_07

lecture_notes_11_14_07 - ASSORTATIVE MATING Mating between...

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1 Johanne Brunet Biocore 301, Fall 2007, Population Genetics LECTURE summary for November 14, 2007 Lecture 2: Learning objectives Determine whether a population is at Hardy-Weinberg equilibrium Application of Hardy-Weinberg principle Impact of non-random mating on gene and genotype frequencies IN CLASS ACTIVITY Definition: Genetic polymorphism When there exists more than one allele at a locus in a population When the frequency of the second allele is 0.01 or greater Non random mating If mating is NOT random the simple relationship between allele frequencies and genotype frequencies breaks down Two ways members of a population might mate non randomly: 1. Because they are genetically related INBREEDING 2. Because they are phenotypically similar ASSORTATIVE MATING INBREEDING: mating with close relatives consanguineous mating (first cousin matings) Inbreeding coefficient F : probability that two gene copies in an individual are identical by descent from a common ancestor.
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Unformatted text preview: ASSORTATIVE MATING Mating between organisms that share a similar trait. Flower color in plants especially with pollinator preference for a given color. Religions; races; etc Selfing is an extreme form of Inbreeding Inbreeding and Assortative mating both reduce the frequency of heterozygotes and increase the frequency of homozygotes compared to the Hardy-Weinberg genotype frequencies. Inbreeding and Assortative mating change genotype frequencies but DO NOT affect Gene frequencies. Inbreeding and assortative mating only change the way alleles are combined into genotypes. They do Not change allele frequencies. While inbreeding affects all loci (whole genome), assortative mating only affects locus or loci under assortative mating (for eg. flower color) and any loci tightly linked to that locus. With pure selfing (obligate selfers) the frequency of heterozygotes is 1/2 each generation....
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