1. A gene pool includes all the genes in a population. Allele movement between populations is gene flow. Inherited characteristics of the individuals in a population reflect allele frequencies.
2. In Hardy-Weinberg equilibrium, evolution is not occurring because allele frequencies do not change from generation to generation. In this idealized state, we can calculate the proportion of genotypes and phenotypes in a population by inserting known allele frequencies into an algebraic equation: p2
+ 2pq + q2. The equation also can reveal allele frequency changes when we know the proportion of genotypes in a population.
3. When allele frequencies change, evolution occurs.
4. Nonrandom mating causes certain alleles to predominate because a particular phenotype is more attractive to the opposite sex.
5. In genetic drift, small populations separate from larger ancestral populations and establish a new gene pool, with different allele frequencies. The founder effect and population bottlenecks are forms of genetic drift.
15.3 Mutation Fuels Evolution
6. The deleterious alleles in a population constitute its genetic load.
7. Mutation alters allele frequencies by changing one allele into another and providing new phenotypes for evolution to act on.
12. Balanced polymorphism is a form of stabilizing selection that maintains deleterious recessive alleles because heterozygotes are protected against another medical condition.
