Biogeography is a field of science dedicated to studying the distribution of species on Earth, especially as related to ecological and evolutionary processes. Biogeographical studies of island populations were used by Darwin (such as with Darwin's finches) as evidence of evolution, and island biogeography is still used today as one of the better evidences of evolution.
In Darwin's time, the prevailing creation theory was that species were created separately in the place they lived at the time. Darwin saw in the finches of the Galapagos that one species (that of the probable ancestor of all the island finches) could "radiate" into new species as it became isolated and adapted to new conditions. While not proof of the general theory of evolution, this observation contradicted the prevailing creationary view of the day.
Today biogeography has shown that creatures on islands are usually very similar to the same kinds of creatures on the mainland, but with enough differences to suggest that the island species came from the mainland and subsequently "evolved" its new features.
Fossil evidence has also shown that the distribution of life was very different in the past (for example marsupials in Antarctica). Some evolutionists claim that modern creationists cannot explain biogeography without accepting at least some aspects of the theory of evolution.
Today, creationists generally hold that animal life radiated out from the resting place of Noah's Ark after the Flood subsided. Few believe that species were created in place, and furthermore, most accept that speciation occurs as different lineages within the same created kind diverge and diversify.
While it is true that biogeography is not discussed very often in creationist circles, most of the anti-creationist claims based on biogeography neither prove evolution nor violate the current creation model.