ANTHRO 7 Lecture Notes - Lecture 1: Stabilizing Selection, Genetic Drift, Directional Selection
Document Summary
Anthro 7 midterm review: evolution is descent with modi cation. Descent: inheritance of traits from ancestors > relatedness. Modi cation: change due to natural selection (nonrandom changes > adaption) and genetic drift (random changes: patterns of evolutionary relatedness: closely related species are more similar than distant ones, patterns of adaption, evolution. Not change in individuals during their lifetimes. Inheritance: this variation is transmitted from parents to offsprings > offsprings resemble parents: field study: galapagos" nches (grant&grant) Results: # of nches decreases but frequency of beak depth remains the same > stabilizing selection because both ends have a tness disadvantage. Natural selection: reason: some individuals have higher tness than others, 2 types (results) Directional selection: one end of continuum has a tness advantage > evolutionary change. Changes only when there is natural selection. The frequency remains the same without evolutionary in uences > hardy-
