Gause's competitive exclusion principle, or sometimes called--Gause's Law, states that when two species are competing for the same resources, the one that is best adapted or that has an advantage over the other will survive and the other may become extinct. He placed Paramecium caudatum and Paramecium aurelia together in a test tube with the same food supply. P. aurelia grew faster than P. caudatum and when grown together, P.aurelia outmultiplied and eliminated P. caudatum. In nature, species tend to have niches that are very specific and this reduces direct competition allowing for more species to survive. For instance, in one tree, there may be seed eating birds, fruit eating birds, birds feeding at the top, middle or bottom of the tree. All of these niches reduce competition. Gause realized that a direct competition between two different species cannot go on forever and one will eventually perish.