BIO 370 Lecture Notes - Lecture 8: Genetic Drift, Selection Coefficient, Gene Flow
Document Summary
2/19 - lecture 8 - population structure and genetic drift (chpt. Balanced polymorphism case - a system of genes in which two alleles are maintained in stable equilibrium because the heterozygote is more fit than either of the homozygotes. Underdominance - selection against the heterozygote, causing disruptive selection and divergent genotypes. Simple migration model - island model (two populations) Knowing the frequency at a particular state predict frequency of alleles after gene flow. Ex: plants near mines - tolerate toxins in the soil. Selection on mine site for resistance due to the toxin present (selection on standing variation for tolerance) No standing variation - have to wait for mutation (rate of mutation is really low - could take forever) Those who survive greater offspring (increase of frequency on mine site) Gene flow can swamp the alleles selection are favoring (balance of local adaptation) - constraining adaptive evolution. Direction of gene flow = wind (left to right (upwind))
