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Rampal Etienne
University of Groningen, The Netherlands
Stochasticity in Community Ecology: the Neutral Model and a Dispersal-limited Sampling Formula
Most models describing the structure of ecological communities are deterministic. An exception is the now famous (or infamous) neutral theory of biodiversity by S.P. Hubbell which he launched in his 2001 book. He makes two assumptions: all species are equivalent and the community has constant size. He put these two assumptions into action in a stochastic individual-based model with the basic ecological processes of birth, death, speciation and dispersal, and was able to explain observed patterns such as the species-abundance distribution and the species-area relationship. While Hubbell obtained most of his results by simulations, others (mostly physicists) have tried to find analytical expressions. One of these is a new sampling formula I derived for the probability that a particular species abundance distribution is observed. Here I summarize the model, the controversy it has caused, and I outline the approach to derive the new sampling formula (that views dispersal as a sampling effect), and I discuss the prospects of neutral (stochastic) theory in community ecology.
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