Energetic Constraints and the Relationship Between Body Size and Home Range Area in Mammals

Recent theoretical developments to explain the unimodal and asymmetric distribution of body sizes among species in higher taxa have yielded predictions for related demographic and life history traits. In particular, it has been predicted that there is an energetically optimal body size (M*) for terrestrial mammals at ∼100 g, and that the relationships of many biological characteristics will change slope or even sign at this point. We reanalyze a well-known data set on the relationship between home range size and body size in mammals. If the distribution of home range sizes as a function of body size is energetically constrained, then it is reasonable to assume that the lower size limit of a home range for a given body mass will also be constrained. To evaluate this hypothesis, we predicted that the relationship between minimal home range size and body size is nonlinear, and that the smallest home ranges should correspond to species in the vicinity of M*. Our data tentatively support both hypotheses but constitute a clear call for more comprehensive analyses with larger data sets.