Bio-geography is how species are places/distributed across the earth. With this being said bio-geographical data show that all current life forms have adopted their present setting from their ancestors. Since, groups of the same related organisms derive from the similar ancestors would be near each other. If evolution wasn't true then there would be no need for organisms to be grouped so close together. Most geographers gather current information from now living species and compare it with historic creatures to show a pattern. These species are only located in certain areas with specific climates and if they were spread equally around the world it would be rather hard to explain a natural evolutionary change. Hope this Helped :)