Lizard home ranges revisited: Effects of sex, body size, diet, habitat, and phylogeny

The area traversed by an animal during food gathering, mating, and other routine activities is termed the home range (HR), and its size is believed to reflect behavioral and physiological requirements (e.g., access to mates and food). We evaluated both biological and methodological factors that may affect estimated HR sizes of lizards. We compiled a database of nearly 500 published sex X population data sets. These yielded usable data for 108 populations from 60 species, all with both sexes represented. Initial analyses indicated pervasive sex differences, so sexes were analyzed separately with both conventional and phylogenetically based statistical methods. First, we conducted conventional analyses of covariance, which treat each data point as statistically independent. Second, we repeated these analyses while comparing members of two major clades represented in our database, Iguania and Autarchoglossa. Third, we repeated the analyses after designating smaller clades, nested within major clades. Fourth, we performed a fully phylogenctic analysis via independent contrasts and a composite phylogeny assembled from published studies. All analyses showed highly significant effects of both biological (body size, diet, habitat type) and most methodological (calculation method and minimum number of sightings per individual, but not study duration) factors and covariates tested. The conventional analysis comparing Iguania and Autarchoglossa en toto indicated a significant difference, as has been suggested in the literature. The analysis with nested minor clades, however, revealed differences among these but not between the two major clades. The analysis with phylogenetically independent contrasts indicated no statistically significant differences either among minor clades or between major clades. We also used our database to compare the scaling of HR area to body mass, using recently published allometric equations for field metabolic rates of lizards. The similarity of allometric slopes suggests that, interspecifically, HR size scales directly with energetic requirements. Intraspecifically, however, we found that males in both Autarchoglossa and Iguania consistently had larger HRs than did females. This difference, presumably related to the need to maximize access to females, may impose a "cost of reproduction" on males.