ANT 101 Lecture Notes - Lecture 22: Genetic Drift, Evolutionary Anthropology, Disruptive Selection
Document Summary
Helps explain phenotypic diversity seen in nature. Directional selection: evolutionary process that tends to favor either higher or lower values of a character than its current average value; promotes phenotypic variation and suggested to be the primary cause of speciation. Stabilizing selection: occurs when an average phenotype within a population is fittest. Acts to reduce variations inform, keeping the phenotypic aspects of individuals in a population constant through time. Most common form of natural selection in animals. Disruptive selection: occurs when individuals at both extremes of a range of phenotypes are favoured against those intermediate between them. Evolutionary significance of disruptive selection lies in the possibility that the gene pool may become split into two distinct gene pools. Thus, sustained disruptive selection can increase genetic variance, a prerequisite for speciation. Although it can increase variation, these selection modes are rarely sustained long enough for speciation to occur. Biological evolution and natural selection not necessarily the same thing.
