Determining the density dependence of immigration and emigration of benthic stream invertebrates: theoretical considerations

Abstract

Simple mathematical models are formulated to describe density independent and density dependent dispersal. These models clarify hypotheses of density dependence and may be manipulated easily to suit particular applications. The models demonstrate that the initial composition of a species aggregate must be controlled before valid conclusions can be drawn about the density dependency of the aggregate's dispersal. Stochastic models of emigration are derived to assess the power of particular experimental designs and statistical techniques to discriminate a known form of density dependent emigration.