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.

The differences of populations in geographical separations to the point where they are recognized as isolated species: Allopatric speciation exists when two biological populations of the same species become separated as a result of geographical changes or population dispersal and whose areas of existence are entirely disunited to such a degree that they do not occur in any one place together.

Allopatric speciations involve changes that take place with related organisms to the point where they are different enough to be considered separate species and this happens when populations of certain species are separated and adapt to their new environment or conditions (physiological, geographic, or behavioral).