The increase in species with the area in which they occur (islands, lakes, etc.) is one of the first empirical patterns identified by ecologists and biogeographers.
In classical metapopulation models extinction and immigration determine the persistence of a species in a patch system. Here we will do basically the same thing, only this time we will consider several species at the same time and instead of population size our interest will be the number of species in each spot, which in this case will be islands.
