Role of differential survival in a model of species–area curve

We study the species–area relation (SPAR) for islands using a lattice stochastic model. At each time step new species immigrate into an island with a fixed probability. Each species is assigned randomly with a set of values for the dispersal rate and death probability. We investigate the hypothesis that insular communities constitute a non-random selection of species biased in favor of a small number of generalists. The inclusion of a difference in the species ability to compete for the resources available on the island depresses the slope of the SPAR from unity down to values comparable to the ones observed in field data. The bio-geographical meaning of these findings, including turnover rates and the essential differences between the dynamics on islands and continents are discussed.