THE RELATIONSHIP BETWEEN BODY-SIZE AND POPULATION ABUNDANCE IN ANIMALS

On average, large-bodied species live at lower densities than small-bo died ones. Early studies suggested that population densities might sca le so that the energy use of a population is independent of body size. However, recent work shows that, at the scale of local communities, t his is rarely true and that the pattern varies among taxonomic or ecol ogical subsets of those communities. Energetic considerations may only be relevant to the densities of more abundant species. In fact, withi n natural assemblages of organisms, the underlying relationship is ver y variable; in subsets of those assemblages, ecological processes such as competition may structure abundance patterns.