BIO120H1 Lecture Notes - Lecture 5: Heterozygote Advantage, Zygosity, Genetic Drift
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BIO120H1 Full Course Notes
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Document Summary
Demonstrated the evolutionary significance of genetic variation leading to several key questions and development of the field of ecological & evolutionary genetics. Genetic drift can result in the loss of rare alleles, and can decrease the size of the gene pool. Mixing of genes influences the structuring of diversity over a large spatial scale. Polymorphism (p) = proportion of gene loci that are polymorphic (presence of gene variation) Heterozygosity (h) = average frequency of heterozygous individuals per gene locus (amount of gene variability) Less fit types maintained by repeated mutation. Heterozygote advantage, frequencydependent selection, fitness varies in space and time. Different types do not differ in their fitness hence none eliminated by selection. Results of artificial selection experiments on quantitative traits. Selection responses demonstrate that abundant genetic variation exists for polygenic (quantitative) traits. No information on key population genetic parameters (p & h) No solution to the question: what maintains genetic variation. Can be used in nearly any organism.
