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Unformatted text preview: Chapter 14 Human Genetic Variation People vary in blood type and incidence of certain genetic diseases Genetic and environmental variation (genetics and shared environment cause offspring to be very similar) Variation among versus within groups and their causes Variation in Traits influenced by Single Genes I.e. Sickle Cell, Single Language Impairment-DominantFOXP2 gene recent dispersal around time of Homo sapiens (3 in mice 1 in chimpanzee nucleotide substitutions) Causes of Genetic Variation Within Groups Mutation maintains variation at low frequencies NS removes genes but they are constantly reintroduced through mutation Selection-mutation balance Selection can maintain variation within populations if heterozygous individuals have fitness advantage Like in Sicke-Cell (balanced polymorphism) equilibrium frequency of S versus normal allele Tay-Sachs Tuberculosis heterozygote advantage Changing environment so genes havent caught up i.e. NIDD and IDD IDD happens because immune system kills pancreas-SUCKS and not ever adaptive; NIDD helps build fat reserves i.e. NauruIDD happens because immune system kills pancreas-SUCKS and not ever adaptive; NIDD helps build fat reserves i....
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- Spring '11