Divergence of adjacent populations into distinct species while some gene flow persists across their contact region. Spatially varying natural selection and the development of reproductive isolation can maintain differences despite exchange. It is a geographical mode distinct from complete separation in allopatric speciation and initial coexistence without such a barrier in sympatric speciation.
Articles by others on the same topic
Parapatric speciation is a mode of speciation that occurs when populations of a species become geographically isolated from one another, but still maintain a non-overlapping distribution. This can happen in conditions where two populations are adjacent to each other and share a border, but are limited in their interbreeding due to ecological differences, environmental gradients, or other factors.