The ecology of metabolic phenotypes: from cells to populations

Metcalfe, Selman, Hartley

Metabolic rate is a fundamental life history trait. It determines the energetic costs of living and its importance is recognised across all biological disciplines. Metabolic rate is linked, and in some cases thought to drive, variation among and within species in growth, size, reproductive strategies, senescence rates and longevity. Yet it shows remarkable intra-specific variation: some individuals consistently have two or three times the maintenance costs of conspecifics the same size, age and sex. The predicted consequences of this variation in energy demands are central to our understanding of optimal life history strategies and resource allocation trade-offs. But how is this intra-specific variation maintained?

While we believe, with good reason, that it must be a key fitness-related trait, attempts to link metabolic rate to fitness variation have nonetheless yielded very inconsistent results. This project is testing the prediction that different microhabitats will favour specific combinations of metabolic traits, leading to spatial and temporal structuring of metabolic phenotypes within and across populations. It is using experimental manipulations at levels ranging from the cellular to the population.

The primary objective is to test whether variability in metabolic traits is maintained through context-dependent fitness. The results of this work  will reveal how metabolic physiology is a key determinant of the ability of organisms to cope with variable environments, so explaining the persistence of variation in physiological traits and  increasing our understanding of the likely consequences for organisms of environmental change.