Final answer:
It takes little migration, or gene flow, to counter the effects of genetic drift, which includes the founder effect that can lead to an increase in genetic disorders. Gene flow introduces new alleles to a population, increasing genetic diversity.
Step-by-step explanation:
It takes little migration to counter the effects of genetic drift. Genetic drift is a mechanism of evolution that occurs due to random chance events that affect which alleles are passed to the next generation. A particular type of genetic drift is the founder effect, which can occur when a new population is established by a very small number of individuals from a larger population. This results in an unrepresentative sample of alleles in the new population, which can lead to an increase in genetic disorders or particular traits, as observed in the Afrikaner population of South Africa with high incidences of Huntington's disease and Fanconi anemia. However, with the introduction of new individuals into the population, known as gene flow, the effects of genetic drift and the founder effect can be mitigated, as new alleles are introduced, increasing genetic diversity and reducing the chances of such disorders being prevalent.