The macroecology of community energy use in terrestrial vertebrates

Energy is a fundamental property of nature that governs all ecological processes and interactions. On the individual level, an organism’s rate of energy flow can be quantified by measuring its metabolic rate. According to the metabolic theory of ecology, metabolic rate ultimately dictates the pace of life at all levels of biological organisation from individuals to entire ecosystems. As such, individual species rates can predict community-level functioning. Daily rates of community energy flow for 423 ecological samples, representing three well-studied terrestrial groups (bats, birds and small mammals), were calculated by scaling up from individual metabolic rate. While community energy flows vary with climate only on a per-gram basis, there are clear group-specific biogeographic patterns of community energy use. Bat communities have considerably higher rates of energy flow in the Neotropics, while bird and small mammal communities have consistently lower per-gram rates of energy flow in the tropics. Anthropogenic factors also negatively impact rates of community energy flow, although these differ depending on group, further highlighting the group-specific nature of these patterns. Making further comparisons with other groups would be a valuable pursuit towards understanding the ecology of energy use and the true extent of human-induced impacts on ecological communities.