vicariant

noun Biology.

1. the geographical separation and isolation of a subpopulation, resulting in the original population’s differentiation as a new variety or species.

noun

1. any of several closely related species, races, etc, each of which exists in a separate geographical area: assumed to have originated from a single population that became dispersed by geological events

1. The separation or division of a group of organisms by a geographic barrier, such as a mountain or a body of water, resulting in differentiation of the original group into new varieties or species. See also speciation.