BIO 311D Lecture Notes - Lecture 31: Vitamin D Deficiency, Heterozygote Advantage, Zygosity
Document Summary
Bio 311d, dr. donald levin, lecture #31, 12 april 2017 (all images are taken from dr. levin"s lecture slides, which are available on his website http://www. sbs. utexas. edu/levin/bio311d/) Review of last lecture: high frequency (0. 2) of sickle cell anemia in parts of africa, heterozygote advantage over homozygotes, smaller percentage infected. Frequency of alleles for thalassemia (actually the sum for alleles that lead to various forms: frequency greater than 0. 2 (relatively high) in some areas because of heterozygote advantage in malarial environment, balance in selection, very low in ireland. For g6pd enzyme deficiency: greater frequency than 0. 2 in saudi arabia and parts of africa, very low in europe. Agents of evolutionary change: mutation: ultimate source, rare for individual to mutate, gene flow: potent change agent, nonrandom mating: commonly inbreeding, decreases heterozygosity, genetic drift: only in a very small population, selection: produces adaptive evolutionary changes.
