BIO120H1 Lecture Notes - Lecture 5: Genetic Drift, Heterozygote Advantage, Balancing Selection
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BIO120H1 Full Course Notes
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Lecture 5: maintenance and measurement of genetic variation. 1930-50 theoretical population genetics was initiated by ra fisher, jbs hawthorne and. S wright and provided foundations for neo-darwinism and new synthesis : continuous variation and darwinian natural selection entirely consistent with. Polymorphism (p)- proportion of gene loci that are polymorphic. Heterozygosity (h)- average frequency of heterozygous individuals per gene locus (site on chromosome usually a gene) Selection experiments on quantitative traits in diff groups of organisms. Controlled breeding of selection of individuals for many generations (artificial selection) Randomly breed, take top 5% bristle length. When it hits peak on graph (that"s go back to randomization) Results: selection responses demonstrate abundant variation for polygenic (quantitative) traits, no info on key population genetic parameters (p&h) also comparative studies difficult as traits often group specific. No best type, balancing selection favor selection reduces diversity diversity. Allozyme gel electrophoresis answers what proportion of genes are variable.
