SPECIES-ABUNDANCE, BIOMASS, AND RESOURCE-USE DISTRIBUTIONS

The allometric relationship across species between population density and body size determines whether community resource use is distributed more equitably, less equitably, or the same as inferred from the species-abundance distribution. The relationship between body size and population density within the 72 natural communities that were studied typically takes a form in which community resource use is less equitably distributed than are the species' abundances. Small-bodied species living at densities well below those predicted by allometric models use a much smaller share of the community resources than do larger-bodied species. Knowledge of the ecological forces that determine the relationships between body size and population density within communities is central to understanding the patterns of community resource use. Relationships between population density and body size that emerge at the community level may be explicable, at least in part, by evolutionary principles applied to characteristics of individuals of different sizes and ways of life.