1. Describing or relating to groups of similar biological organisms, populations, or species that could interbreed but don't because they are geographically separated into other areas: Allopatric speciation occurs when two populations are geographically isolated from each other.

Allopatric species often use the same kind of habitat and food resources in different areas; however, they are unable to interbreed because of distances or geographical barriers.

2. Occurring in separate, non-overlapping geographic areas: Usually applying to allopatric populations of related organisms that are unable to crossbreed because of distinct geographic separations.