BIO342H5 Lecture Notes - Lecture 23: Lactase Persistence, Melanin, Cholecalciferol
Document Summary
Greatest genetic diversity is found in modern africans. Why is there so much genetic diversity within africa: four non-exclusive explanations, old lineages: multiple lineages have had time to diverge for up to 170,000 years, large population sizes: population sizes have remained relatively larger than non- African populations (=less drift: adaptation: differences in ecology, technology and culture have selected for different adaptations, admixture: reverse migration by non-africans, and population interbreeding has lead to admixture. 8-10% of our genes) showed a signature of selection (adaptive evolution: african (3486), european (2803), chinese (2783), japanese (2783, date when these selected alleles arose and started to exhibit adaptive evolution (coalescent methods) In fact, our evolution seems to have in fact increased in recent history. Increased population size = increased efficiency of natural selection (due to decreased influence of genetic drift: our ecology has changed (human migration farming) leading to novel selection.
