ANTHROP 2E03 Lecture Notes - Lecture 7: Selection Coefficient, Genetic Drift, Gene Flow
4 Feb 2018
School
Department
Course
Professor
Document Summary
Natural selection - tendency for individuals with traits beneficial to survival and reproduction to pass those traits (alleles) on. Happens when there are differences among genotypes in their ability to survive and reproduce. This differential ability is usually referred to as fitness. Absolute fitness of genotype compared to most fit genotype. Another way to describe the role of selection is using the selection coefficient: Proportional reduction in fitness of a genotype with respect to the genotype with the maximum fitness (w=1) 0 (genotype with the maximum fitness) 1 (genotypes don"t survive or reproduce) For a known s, we can use w = 1 - s. The effect of selection on allele frequencies will depend on: Differences are large - effect of selection is strong. Strong selection - allele frequency will change fast in the population from one generation to the next. Gene flow : allelic frequencies change with the addition or subtraction of (groups of) individuals.
