Biology 1002B Study Guide - Midterm Guide: Allele Frequency, Genotype Frequency, Antigenic Shift
5 Apr 2018
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Microevolution: change in frequencies of alleles or heritable phenotype in a population over time. Qualitative variation: they exist in two or more discrete states, without an intermediate. Allele: a member of a gene pair that occupies a locus on a chromosome. 1. directional selection: individuals near one end of the phenotypic specturn have the highest relative fitness, shifts a trait away from the existing mean and towards the favored extreme. 2. stablizing selection: individuals expressing intermediate phenotypes have the highest fitness and therefore will reduce the genetic and phenotypic variation. 3. disruptive selection: extreme phenotypes have better fitness than intermediates(alleles producing extreme phenotype is now common and promotes polymorphism) ---know the calculations for genotype frequencies, allele frequencies, relative abundance--- Hardy weinberg principle: conditions that a population achieves genetic equilibrium. 2. the population is closed to migration from other populations: population is infinite (no genetic drift)
