Retrieved from https://en.wiktionary.org/w/index.php?title=monocline&oldid=48089207
Speciation, the formation of new and distinct species in the course of evolution. Speciation involves the splitting of a single evolutionary lineage into two or more genetically independent lineages.
Allopatric speciation is just a fancy name for speciation by geographic isolation, discussed earlier. In this mode of speciation, something extrinsic to the organisms prevents two or more groups from mating with each other regularly, eventually causing that lineage to speciate.