premise: Species distribution can be understood through only through speciation.
hypothesis: Cospeciation is a form of coevolution in which the speciation of one species dictates speciation of another species and is most commonly studied in host-parasite relationships . Species distribution . Biogeographers try to understand the factors determining a species ' distribution . It is very useful in understanding species distribution through factors such as speciation , extinction , continental drift , glaciation , variation of sea levels , river capture and available resources .