Metabolic Correlates of Anuran Behavior

Frogs exhibit extensive diversity in their repertoires of social,reproductive, defensive, and predatory behavior, and in themetabolic processes that support these activities. Three aspectsof anuran biology (foraging mode, post-metamorphic ontogeneticchanges in ecology, and reproductive behavior) are analyzedfor their correlations with metabolic capacities. Anurans thatforage widely for prey have greater capacities for aerobic ATPproduction than do sedentary foragers. This relationship appearsto extend to intraspecific analyses; significant differencesin aerobic capacity among populations of a species of dart-poisonfrog are associated with differences in feeding ecology. Ontogenetic change in metabolic capacity is directly coupledwith ontogeny of behavior. The magnitude of post-metamorphicchanges in physiology, behavior, and ecology appears to be relatedto differences in life history. A relatively short larval stageand small body size at metamorphosis, such as that found inAmerican toads, are associated with extensive post-metamorphicchanges in oxygen carrying capacity of the blood, cardiac musclemass, and aerobic capacity of predispersal juveniles. In contrast,predispersal juveniles of species with long larval periods andlarge body size at metamorphosis possess adult physiologicaland behavioral features. Anuran reproductive activities, especially calling to attractmates, are energetically demanding, suggesting that the behaviorof male frogs at a breeding pond may be limited by their metaboliccapacities. However, the only study that has attempted to relateindividual variation in reproductive behavior to individualvariation in aerobic capacity found no correlation between thosecharacteristics. The complexity of anuran biology ensures that physiologicalcharacteristics of anurans reflect many aspects of ecologyandbehavior, some of which act independently, others in concert.Carefully designed experiments that incorporate both field andlaboratory data are required to assess these interlocking features.