Answer; Genetic drift Migration is when individual join new populations, which causes a change in gene frequencies that results in evolutionary change, which is called Genetic drift.
Explanation; Genetic drift is the process by which allele frequencies are altered in a population due to chance. Genetic drift results in a change in gene frequencies because the population size is so small that chance occurrences can alter gene frequencies.
Migration is when individuals join new populations, this
causes a change in gene frequencies that results in evolutionary change, which
is called gene flow or gene migration. Gene flow can change the incidence and
the variety of alleles in the populations because of the migration of organisms
that reproduce in a different population. This results to a new combination of
traits.