We can see why, if there exist very closely allied or representative species in two areas, however distant from each other, some identical species will almost always there be found.
Halaber uler dezakegu zergatik aurkituko den zenbait espezie berdin, ia beti, espezie oso ahaide edo errepresentagarriak existitzen diren bi herrialdetan, bata bestetik denik urrunen egonik ere.