Final answer:
Migration can cause Hardy-Weinberg disequilibrium due to increased gene flow, which introduces different alleles into the recipient population's gene pool. Genetic drift can also result from various events, such as migration, differential survival, random events, and mutations, leading to changes in allele frequencies over time and potentially decreasing genetic diversity in certain contexts. The correct option is B.
Step-by-step explanation:
The migration can cause Hardy-Weinberg disequilibrium as a result of increased gene flow. When individuals from one population migrate to another, they can bring different alleles into the gene pool, thereby altering the allele frequencies in the recipient population. This is an example of gene flow, which is one of the mechanisms that can lead to genetic drift.
Changes in the gene pool due to migration can increase the genetic diversity if the incoming alleles are different from those present in the recipient population. In contrast, if a mutation introduces a new allele, as in the case with fur color in rabbits, genetic diversity could increase, leading to genetic drift.
Several events can lead to genetic drift, which causes allele frequencies to change over time. If a group of white rabbits migrates into a population of brown rabbits, the allele frequency for white fur would increase, suggesting a drift from the previous equilibrium. Differential survival and reproduction, such as white rabbits being more visible and thus more prone to predation, can also lead to genetic drift by decreasing the frequency of the white fur allele.
Moreover, random or chance events can cause genetic drift. A significant event, such as a natural disaster that kills off individuals carrying specific alleles, can lead to a decrease or loss of those alleles in the population, hence disrupting the equilibrium. Genetic drift is also highlighted in smaller populations, where random fluctuations in allele frequencies are more pronounced, further contributing to Hardy-Weinberg disequilibrium.
Hence, Option B is correct.