Metabolic Rate Diversity Shapes Group Performance in Honeybees.

Abstract

AbstractThe metabolic theory of ecology posits that the functional properties at any level of biological organization are a function of the metabolic rate (MR) of its constituent units, although we know little about how heterogeneity among them shapes group-level performance. Using honeybees as a model system, we leveraged the differences in MR associated with "slow" and "fast" malate dehydrogenase alleles to breed genetic lines with low MR and high MR, respectively, and created four experimental groups with different phenotypic compositions. We then measured MR, energetic intake, thermoregulation, and survival of these groups in low- and high-resource conditions. Contrary to expectations, neither the monomorphic fast groups nor the polymorphic (1∶1 slow-to-fast) groups showed a consistent advantage over other groups, but the performance of all groups was consistently better under high-resource conditions. MR had a strong influence on the other performance traits, more so under low-resource conditions. We quantified the effect of heterogeneity in the polymorphic groups as a diversity effect and found different impacts of metabolic heterogeneity, depending on the specific performance measure in question. We discuss these results in the context of how MR plays an important role in shaping division of labor and social evolution.