L41 BIOL 2970 Lecture Notes - Lecture 40: Genetic Drift, Fitness Landscape, Sewall Wright
17 Dec 2017
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Document Summary
New definition in context of fisher"s quantitative genetic model. Natural selection -- heritable (= additive) variance in fitness; destroys heritable variance in fitness. Changes allele frequencies in gene pool until it destroys heritable variance in fitness. Fitness as a quantitative phenotype -- expected number of offspring of a genotype. Sufficient parameter for mathematical models of natural selection. Components: viability (probability of surviving to adulthood), mating success (probability of finding a mate), fecundity/fertility (expected number of offspring) -- also environmental context important. Dna encodes information that interacts with the environment to influence phenotype -- if influences viability, mating success, and fecundity (combined into a measure of fitness), influences the probability of dna being replicated and passed on to next generation. Fisher"s fundamental theorem of natural selection -- rate of increase in fitness of a population at any time equals its additive genetic variance in fitness at that time (a single-locus model)
