MODELS OF SPECIES ABUNDANCE - A CRITIQUE OF AND AN ALTERNATIVE TO THE DYNAMICS MODEL

Species abundance patterns in natural communities were analyzed using the recently described 'dynamics model'. Although the dynamics model is based on biological processes, simulation of which yields patterns similar to those reported for natural communities, 3 shortcomings to the model have been identified: (1) patterns identical to those predicted can also be derived for non-biological communities; (2) the examples presented to validate the model are inadequate to assert with certainty that competition is actually the factor responsible for the said patterns, as the model predicts; and (3) its parameters are of limited usefulness. In view of the hierarchical organization of natural systems, use of the Zipf-Mandelbrot model, developed in accordance with information theory, is proposed. Various examples of natural communities were fit to this latter model to produce an analysis of community structure in relation to the physical environment and the biological response of component organisms. The Zipf-Mandelbrot model was found to provide a good statistical description of the structure and transformation of natural communities, under the assumption that the habitat can be considered hierarchical in structure.