A founder effect, as related to genetics, refers to the reduction in genomic variability that occurs when a small group of individuals becomes separated from a larger population. Over time, the resulting new subpopulation will have genotypes and physical traits resembling the initial small, separated group, and these may be very different from the original larger population. A founder effect can also explain why certain inherited diseases are found more frequently in some limited population groups. In some cases, a founder effect can play a role in the emergence of new species.
Founder effect can result in the smaller population that left the larger population to have less genetic diversity. And the way I look at this is, the arc of Africa migration 100,000 years ago created what is considered the original founder effect, in the sense of the small group of people that left Africa to populate the rest of the world actually lived with only a subset of the population that existed, the genetic variation that existed at that time.
Division of Intramural Research