Vicariance biogeography

Let us look at one of the main modern research programs that studies the relation between biogeography and continental drift. It is called vicariance biogeography.

The drifting apart of tectonic plates is the sort of event that could cause speciation. If the splitting of the land and of the species on it do coincide, the result is two species occupying complementary parts of a formerly continuous area that was occupied by their common ancestor. This is an example of a vicariance event. (Vicariance means a splitting in the range of a taxon.)

In theory, continental drift is just one process that could split a species' range. It could also be that a species was split by parapatric speciation, or some other process (like mountain building, or the formation of a river) that subdivided an area. In any such case, the result would be a pair or more of species occupying the new subsections of the ancestral species range. According to the theory of vicariance biogeography, the distributions of taxonomic groups are determined by splits (or vicariance events) in the ranges of ancestral species.