AP BIOLOGY

Detailed explanation-1: -Natural selection, genetic drift, and gene flow are the mechanisms that cause changes in allele frequencies over time. When one or more of these forces are acting in a population, the population violates the Hardy-Weinberg assumptions, and evolution occurs.

Detailed explanation-2: -Migration will change gene frequencies by bringing in more copies of an allele already in the population or by bringing in a new allele that has arisen by mutation. Because mutations do not occur in every population, migration will be required for that allele to spread throughout that species.

Detailed explanation-3: -Answer and Explanation: There are four primary mechanisms that alter the allele frequencies in the population. These include Natural Selection, Genetic Drift, Mutations and Gene Flow.