Final answer:
Migration leads to Hardy-Weinberg disequilibrium through limited gene flow, which introduces new alleles or changes the frequency of existing alleles, violating the principle's condition of no allele migration.
Step-by-step explanation:
Migration can cause Hardy-Weinberg (HW) disequilibrium as a result of limited gene flow. When individuals move from one population to another, they can introduce new alleles into the receiving population's gene pool or alter the frequencies of existing alleles. This process, known as gene flow, is a violation of the Hardy-Weinberg principle, which assumes that allele frequencies remain constant in the absence of evolutionary forces.
Gene flow can increase the genetic variation within a population by introducing new alleles, and sometimes it leads to an increased heterozygosity if the incoming alleles are different from those already present in the population. It disrupts the HW equilibrium because one of its key conditions is that there must be no migration of alleles into or out of the population. This migration, or gene flow, can have various impacts, like potentially enabling genetic drift, especially in smaller populations where the introduction or loss of alleles can significantly change allele frequencies.