The goal of my research is to understand various mechanisms that influence the distribution and abundance of terrestrial vertebrate ectotherms. Specifically, I have been interested in how environmental variation (temperature and food abundance) interacts with time budgets and physiological processes of ectotherms to affect their allocations to growth and reproduction. Thermal effects impinge on the allocation of energy and resources to the competing functions of maintenance, growth, reproduction, and storage which in turn, produce variation in population level processes. My favored approach to these problems is to use comparative bioenergetics to learn about constraints and tradeoffs that operate on the physiological performance of individuals. Lately, my interests have expanded to address proximate and ultimate influences on the evolution of sexual size dimorphism (also a bioenergetic problem) the use of individualbased physiologically structured simulations of growth, reproduction and population dynamics for predicting the responses of populations to environmental change, and implications of bioenergetics for conservation.