O'CONNOR, M. P.*; SIEG, A. E.; DUNHAM, A. E.; Drexel University; Drexel University; University of Pennsylvania: Linking physiological effects on activity and resource use to population level effects

Ecological theory has long recognized that population level phenomena like growth, reproduction, mortality, activity and spatial distribution depend on physiological processes. Those processes link the abiotic and resource environments to processes of interest to population, community, and conservation ecologists via the physiome of the organism. Physiological ecology has a long history of examining those linkages, either piecemeal or, when possible, in integrated form. Multiple levels of integration are interposed between the environment, its afforded opportunities for activity and resource acquisition, the physiological constraints on that activity and resource processing, the allocation of resources to life history/demographic processes, and the population level consequences of those processes. Thus, attention is usually focused on situations in which a single physiological process dominates or entirely precludes activity of an animal. We propose that adamantly mechanistic and data based models of individual energy budgets can help bridge multiple levels of integration to link environmental and physiological information to population level processes of interest to conservation biologists. We provide three examples where such models may be useful in terrestrial ectotherms. First, we consider the canyon lizard, Sceloporus merriami, and variation in growth rates at different elevations in west Texas. Second, we examine the hydric and thermal constraints on activity and survival of wood frogs, Rana sylvatica, in Missouri. Finally, we ask what effects water and temperature might have on desert tortoises, Gopherus agassizii, in the Mojave desert. In each case, we argue that models not only suggest constraints on the animalís ecology, but also identify variables that need further consideration.