These small, naturally occurring limestone pools in Jamaica provide habitat for communities of aquatic insects, worms, snails, and a variety of zooplankton. These invertebrates form food webs (predators and their prey) as well as guilds of competitors that share a common food. Rain storms flood the pools periodically, displacing some organisms from one pool to another. This movement, a kind of passive migration, allows species to colonize new pools. It also causes the species composition of different pools to be similar to each other.
Ecological Neutral Theory states that the composition of communities, and the relative abundance of species in communities, are the result of simple random demographic processes, including random birth, death, and passive migration. However, the effects of predators and competitors can non-randomly extirpate (kill-off) species within a particular pool, altering the composition and relative abundance distribution of the community. To test the ability of neutral models to predict the observed community patterns, we compared the relative abundance of species in different pools and in the same pool in different years, to the expected abundance that would result from random birth, death, and inter-pool migration. We also compared the identity and relative abundance of species in the same pool at two different predator densities (high and low). Finally, we tested the ability of neutral models to reproduce the observed distribution of species relative abundance at the scale of a metacommunity of 50 pools. See Community-Metacommunity Dynamics of Aquatic Invertebrates.
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