Final answer:
Migration is a force that tends to homogenize population allele frequencies through gene flow. Migration introduces new genetic variations and changes allele frequencies, but it can be counteracted by genetic drift and other evolutionary forces, which may lead to population differentiation.
Step-by-step explanation:
Migration is a force that generally tends to homogenize populations in terms of allele frequencies. Gene flow, which is the movement of alleles due to the migration of individuals or gametes, introduces new genetic variations to different populations. When migration occurs, allele frequencies in both the source and the destination populations can change. For instance, if animals from one population with certain genetic traits migrate to another population, they mix their genes with the local gene pool, potentially increasing the genetic diversity and making allele frequencies more uniform across populations.
It should be noted that in contrast to migration, mechanisms like genetic drift can cause allele frequencies to diverge between populations. Therefore, while gene flow through migration tends to homogenize populations, other evolutionary forces such as genetic drift, mutation, and natural selection can lead to differentiation and allopatric speciation.