The founder effect is the reduction in genetic variation that results when a small subset of a large population is used to establish a new colony. The new population may be very different from the original population, both in terms of its genotypes and phenotypes. In some cases, the founder effect plays a role in the emergence of new species.


Founder effect is a phenomenon in the work that we do that refers to the migration of a small group of people from a larger population to go settle in another environment. And they carry along with them a subset of genetic information that existed in the larger population. And because of that, carrying the subset, they actually reduce the amount of genetic variation that exists within a new population now. And as a result of that, they may emphasize certain phenotypes or certain genes, and all this may be deemphasized. So a founder effect can sometimes impact a population in such a way that they may have less of a particular type of gene or more of a particular type of gene. And it can change what we call phenotype, which is the things that we look at like your height, you know, your weight, or having a particular disease or not having a particular disease. So in effect that is what founder effect is.

- Charles N. Rotimi, Ph.D.