Community Structure and Metacommunity Dynamics of Aquatic Invertebrates: a Test of the Neutral Theory

We used a metacommunity of 49 discrete communities of aquatic invertebrates to analyze the dynamical relationship between community and metacommunity species distributions as a test of the neutral theory of biodiversity and biogeography. At the community scale, observed variation in species richness and relative abundance was greater than predicted by neutral models, and revealed important differences among species in competitive ability and tolerance for predation. At the metacommunity scale, species with metacommunity proportions of less than 0.01% (38% of the observed metacommunity) were consistently more abundant than predicted by models. Our results are at variance with the neutral theory, and suggest that the use of an identical survival probability for all species in neutral models misrepresents substantial aspects of community assembly. Nevertheless, building and testing neutral models can provide valuable insights into the processes that determine species distributions.