Similarity in Energy Budgets of Animal Populations

Abstract

A basis is suggested for general patterns which have been observed between various components of energy budgets in animal populations. If all components in energy budgets of animal populations are scaled to a constant (.simeq. 0.75) power of body weight, then within a group of metabolically similar animals: production (P) will be proportional to respiration (R) and vice versa (i.e., the relationship between log production vs. log respiration will have a slope equal to 1); production efficiency (P/P + R) will be independent of body size; and the relationship between production and standing crop (P/B) should vary as body mass raised to the -0.25 power. There is good agreement between these predictions and empirical results reported in the literature. It appears that previous analysis of production and respiration in animal popopulations have identified several groups of metabolically similar animals. Those with high maintenance costs, e.g. homeotherms, have lower production efficiencies than animals whose maintenance costs are relatively low, e.g. poikilotherms. This pattern also appears to hold at smaller scales of observation; for example, carnivores appear to have higher production efficiencies and lower metabolic rates than herbivores. The utility of large-scale interspecific comparisons for generating reasonable and testable hypotheses about certain ecological relationships is demonstrated and additional insights into existing empirical generalizations are provided.