Answer:
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.
Example:
The founder effect is a case of genetic drift caused by a small population with limited numbers of individuals breaking away from a parent population. The occurrence of retinitis pigmentosa in the British colony on the Tristan da Cunha islands is an example of the founder effect