Meeting Abstract

66.1  Monday, Jan. 6 08:00  New macrophysiological insights into old macroecological patterns: energetic constraints on geographic range size in mammals AGOSTA, SJ*; BERNARDO, J; Virginia Commonwealth University; Texas A&M University sagosta@vcu.edu

Geographic range size varies over 12 orders of magnitude in mammals. At macroecological scales, variation in range size is related to body size, which is highly correlated with basal metabolic rate (BMR). In species-rich analyses, the body size-range size correlation is weakly positive. On a log-log scale, the relationship has been described as a triangular constraint space, where small species can have small or large ranges, but as species get larger, they are increasingly restricted to larger ranges. A widely hypothesized mechanism for this pattern is the Energetic Constraint on Minimum Range Size Hypothesis (ECMS): large species have high per capita energy demands and, therefore, require large distributions to avoid demographically-driven extinction. Here, we first present a modified version of the ECMS based on novel analyses of the body size-range size relationship in mammals (n = 3,286). Second, we evaluate the ECMS directly using combined data on body size, basal metabolic rate, range size, phylogeny and latitudinal position of the range for 574 species. We examined energetics in two dimensions: absolute energy demand (BMR) and relative, mass-independent energy demand (MIBMR). Similar to the body size-range size relationship and as predicted by the ECMS, the relationships between range size and BMR and range size and MIBMR were weakly positive and fit into a roughly triangular constraint space, where species with high BMR or high MIBMR are increasingly restricted to larger ranges. Synthesizing our results suggests the mammal species most vulnerable to range size reductions and changes in energy landscapes (e.g., from habitat loss and climate change) are both large-bodied and have supra-allometric MIBMR, but also, small-bodied species with supra-allometric MIBMR are at heightened risk.