The occurrence of related organisms in separate geographical areas with no overlap WordNet 3.0 & Open English WordNet

Allopatric speciation – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model: 86  – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow. Wikipedia

Type of speciation caused by geographic isolation between populations Wikidata