When Is an Island Community in Equilibrium?

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Science  17 Jun 1983:
Vol. 220, Issue 4603, pp. 1275-1277
DOI: 10.1126/science.220.4603.1275


To determine whether the number of species in a biota is in equilibrium requires a colonization model. In a simple Markov model, each species' extinction and immigration probabilities are estimated independently from available data. For one inland and two island avifaunas, a simulation with these probabilities shows that the trajectories of species richness through time do not manifest the regulatory tendencies expected if species interactions cause species richness to be continuously redressed toward an equilibrium.