AP BIOLOGY

Detailed explanation-1: -Mutation can happen any time a gene is copied-including during sexual reproduction as reproductive cells are made. Mutation is how different versions of genes come about in the first place. If those critters reproduce, their gene differences get passed down.

Detailed explanation-2: -For a given population, there are three sources of variation: mutation, recombination and immigration of genes or deletion.

Detailed explanation-3: -Mutations and sexual reproduction increase genetic variation in a population. Natural selection occurs when environmental pressures favor certain traits that are passed on to offspring.

Detailed explanation-4: -Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism’s offspring).