Darwin's finches of Galapagos islands provide evidence in favor of what?

The finches of Galapagos islands provides evidence infavour of biogeographical evolution.

All the varieties of the finches, Sir Darwin conjectured, evolved in the island by itself. From the original seed-eating features, many other forms with altered beaks arose, enabling them to become insectivorous, and vegetarian finches. This process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called Adaptive radiation.