ANTH 337 Study Guide - Midterm Guide: Nutrient Density, Calorie Restriction, Pulse Pressure
Document Summary
Classic example of natural selection leading to human variation: malaria and hemoglobin s, populations experiencing high levels of malaria have high frequencies of hemoglobin s allele, heterozygotes have an advantage in endemic malarial environments. Individuals with a genotype of one hemoglobin a and one hemoglobin s have increased resistance to malaria and do not suffer the often fatal effects of the sickle-cell disease that occur in homozygotes for hemoglobin s. Stochastic gene changes: random changes in allele frequencies in populations of small effective size. Four basic mechanisms can change the frequency of alleles and genotypes within a population: natural selection, mutation. Different mutations are likely to occur in different populations. Alteration of bases in the dna molecule: genetic drift. More important cause of evolution in the past than today: gene flow. Exchange of genetic material between populations through the processes of migration and mating.
