/ˌaləˈpatrikˌspēSHēˈāSHən/
Noun
1. Speciation that occurs when biological populations of the same species become vicariant — isolated from each other to an extent that prevents or interferes with genetic interchange. This can be the result of population dispersal leading to emigration, or by geographical changes such as mountain formation, island formation, or large scale human activities (for example agricultural and civil engineering developments). (wikipedia.org)
2. A speciation in which biological populations are physically isolated by an extrinsic barrier and evolve intrinsic (genetic) reproductive isolation, such that if the barrier breaks down, individuals of the population can no longer interbreed. (biology-online.org)
Syn: Geographic speciation
Word origin: From the ancient Greek allos, “other” + Greek patra, “fatherland”