founder effect

noun

, Biology.

1. the accumulation of random genetic changes in an isolated population as a result of its proliferation from only a few parent colonizers.

Example Sentences

Now that the virus has spread almost everywhere, when we see new variants overtake a population, it is much more likely to be due to selection — improved fitness — than the founder effect.

From Quanta Magazine

The samples are evidence of a founder effect, like a group of birds on a remote island all descended from the same ancestor.

From Popular-Science