Linked from
The 15 pages that link to Allopatric speciation, each with the reason it gives.
EndemismRelated: It can produce species whose entire native ranges lie within separate regions.
Endemic speciesRelated: Isolation can let a regional population evolve into an endemic species.
WallaceaRelated: Sea barriers can divide populations and promote divergence across the region.
Ernst MayrRelated: Mayr emphasized geographic separation as a common route to species formation.