Linking patterns in macroecology

Abstract

Associated with the development of the field of macroecology has been the recognition and analysis of a number of different patterns in the large‐scale abundance and distribution of species. The mechanistic bases of these patterns have usually been considered in isolation, yet the patterns are necessarily linked, as the same individual animals contribute to all of them. Here, a model linking macroecological patterns in abundance, distributional extent and body mass is developed, based on how the finite amount of energy available to the species in a region is divided between them. The energy available to a species is assumed to support some quantity of biomass, which must then be allocated to either many small‐bodied or fewer larger‐bodied individuals. This identifies a necessary link between population size and body mass, which predicts when the variety of relationships between these variables in the published literature are expected to occur. Although framed in terms of energy use by species, the model does not assume that energy per se is necessarily limiting populations. How individuals use space determines the form of relationships between population size and distributional extent, distributional extent and body mass, and population density and body mass. The model additionally allows a number of falsifiable predictions about the anatomy of macroecological patterns. Support for the assumptions of the model is discussed.