ANTH 1001 : Exam 2 Notes
Document Summary
Due to heterozygotes having higher fitness than homozygotes: example: sickle cell trait, hemoglobin consists of 2 alpha and 2 beta polypeptide chains. Each alpha chain has 141 amino acids, each beta chain has 146 amino acids. In a malarial environment, heterozygotes for sickle cell have natural selective advantage over homozygote for normal hemoglobin and sickle cell. Selection acts on the phenotypic/genotypic variability that exists in a pop: pops. Differ in their rbc mutqtions: sickle cell, thalassemia, and g-6-pd. Each rbc variant is selectively advantageous in malarial environment; consequently each variant is perpetuated by natural selectiom. Interaction of natural selection and mutation means that pops. Causes diarrhea: humans can digest milk as babies, but most of us lose the ability after weaning, adults in some pops. Are lactose tolerant: evolution of lactose tolerance, pops. Diversify because of natural selection, but our pops. Extremities adaptation: higher basal metabolic rate, efficient vasoconstriction; maintain higher temp of fingers and toes, pops.
