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Presented at the NABS Annual meeting, Athens, Georgia, 2003
in Tropical Stream Ecology I
Reconciliation of neutral and deterministic models of community assembly in the Cinaruco River, Venezuela
D.A. Arrington1, K.O. Winemiller2, and C.A. Layman2. 1Department of Biological Sciences, The University of Alabama, 2Department of Wildlife & Fisheries Sciences, Texas A&M University
Two classes of models predict community structure: neutral models that assemble communities based on random colonization and extinction dynamics, and deterministic models that assemble communities as a function of ecological dynamics. Shallow-water communities in tropical floodplain rivers are disassembled and reassembled as aquatic organisms repeatedly colonize new areas in response to changing water level, thus a neutral model may be sufficient to predict assemblage patterns. We experimentally manipulated structural complexity and colonization rate of littoral habitats and demonstrate significant effects of both factors on species density of fishes and macroinvertebrates. Interspecific variation in vagility affected assemblage response to habitat complexity. In a second experiment, habitat patches were created sequentially to examine dynamics of patch colonization. Assemblage structure became increasingly non-random with increasing species density. High species density and non-random assemblage structure in patchy habitats of tropical rivers are functions of both colonization dynamics and ecological interactions.
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