Biology 1001A Lecture Notes - Lecture 13: Allele Frequency, Genetic Drift, Natural Selection
Document Summary
Selection, drift, and other disruptions of hardy-weinberg equilibrium (lecture 13) Selection happens anytime when not all the genotypes have the same fitness. If one genotype has an absolute fitness over another genotype, then selection is happening. Selection can result in alleles frequencies changing, which results in evolution. Natural selection for most of time only acts on phenotype of an organisms. Average number of surviving offspring for each genotype is defined as its absolute fitness, w. e. g. Divide by absolute fitness of most successful genotype to calculate relative fitness, w. Aa: 20/20, aa: 15/20, aa: 12/20: most successful genotype always have a w = 1, all other genotype has a max of 1 or less, w = w/w max. No matter which allele starts off been rare or common, it will either decrease or increase that allele to produce equilibrium. It will maintain both alleles in a population. Whichever allele that starts off been common will keep increase.
