Lecture 26 (4-24) - Evolution of Local Populations...

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Evolution of Local Populations Inheritance of Mendelian vs. polygenic traits Geographic distribution of polymorphisms (traits with two ore more alleles at one locus) Adaptations on the local level (population genetics) Polygenic Inheritance Polygenic traits are continuous traits governed by alleles at more than one genetic locus. Continuous traits show gradations, there is a series of measurable intermediate forms between two extremes. Skin color is a common example of a polygenic trait it is governed by 6 loci and at least 12 alleles. Discontinuous Distribution of Mendelian Traits Evolution of Human Skin Color Melanin protects against UV radiation (associated w/ skin cancer) – darker skins in areas of intense UV radiation Vitamin D hypothesis UV radiation synthesizes Vit. D in skin cells Areas of little UV radiation selected for depigmented skin ABO Genotypes and Associated Phenotypes Genotype Antigens on Red Blood Cells ABO Blood Type (Phenotype)
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Lecture 26 (4-24) - Evolution of Local Populations...

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