  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.
