BIOL 1411 1st Edition Lecture 33Outline of Last Lecture I. Variation in Population Outline of Current Lecture II. Variation in Population a. Selectionb. Hardy-Weinberg Lecture- Individual Fitnesso Natural selection acts on the phenotype rather than directly on the genotypeo The reproductive contribution of a phenotype to subsequent generations relativeto other phenotypes is called fitnesso Fitness of a phenotype is determined by the rate of survival and reproduction of individuals with that phenotype relative to others - Sexual Selection: acts on characters that determine reproductive successo If an individual survives but does not reproduce, it makes no contribution to the nest generation o Sexual selection favors traits that increase the chances of reproduction o Intrasexual- with into one sexo Intersexual- opposite sex o Stabilizing Selection: preserves average phenotypeo Directional Selection: favors individuals that vary in one directiono Disruptive selection: favors individuals that vary in opposite directions from the mean - Allele Frequencieso If p is the frequency of allele A, and q is the frequency of allele a, P + q =1 Q=1-po If there is only one allele at a locus, its frequency=1. The population is monomorphic at the locus; the allele is said to be fixed. - Hardy-Weinberg Model o Frequencies of different alleles at each locus and frequencies of genotypes in a Mendelian population make up the genetic structure of the population These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Hardy-Weinberg equilibrium describes a model population in which allele and genotype frequencies do not changeo The hardy-Weinberg model predicts genotype frequencies in a sexual population simply as a product of allele frequencies - Assumptions of the Hardy-Weinberg Modelo Mating is randomo Population size is infiniteo No gene flow- no migration into or out of the populationo No mutationo Natural selection does not affect survival of any genotypes- Hardy-Weinberg Equilibriumo Allele frequencies remain constanto After one generation, genotype frequencies occur in there proportions: Genotype AA As aa Frequency p^2 2pq q^2- Hardy-Weinberg Equation: o P^2 + 2pq + q^2 = 1o At equilibrium- allele and genotype frequencies remain constant - Utility of the Hardy-Weinberg modelo Populations in nature never exhibit the conditions of equilibriumo However, it is useful for predicting genotype frequencies fro allele frequencies, and many populations fit these predictionso Also, because the model describes conditions that would result in no evolution, deviations from the model’s predictions are used to identify mechanisms of
View Full Document
Unlocking...