Energetic constraints and the relationship between body size and home range area in mammals

Recent theoretical developments to explain the unimodal and asymmetric dist ribution of body sizes among species in higher taxa have yielded prediction s for related demographic and life history traits. In particular, it has be en predicted that there is an energetically optimal body size (M*) for terr estrial mammals at similar to 100 g, and that the relationships of many bio logical characteristics will change slope or even sign at this point. We re analyze a well-known data set on the relationship between home range size a nd body size in mammals. If the distribution of home range sizes as a funct ion of body size is energetically constrained, then it is reasonable to ass ume that the lower size limit of a home range for a given body mass will al so be constrained. To evaluate this hypothesis, we predicted that the relat ionship between minimal home range size and body size is nonlinear, and tha t the smallest home ranges should correspond to species in the vicinity of M*. Our data tentatively support both hypotheses but constitute a clear cal l for more comprehensive analyses with larger data sets.