Agustí Muñoz-Garcia

My field of study is Ecological and Evolutionary Physiology, or how organisms adjust their physiological phenotype in a given environmental context. Animals have to assign energy and resources to maximize their lifetime reproductive success. However, physiological limits constraint energy and resource allocation to offspring, although the nature and extent to which these limits operate are poorly understood.

I follow a research framework that aims to use universal principles that can guide my research agenda. This framework is based on the integration of multiple levels of organization that I believe can explain the expression and maintenance of the physiological phenotype in relation to the environment. Environmental conditions trigger the adjustment of the cellular metabolic response in a tissue-specific manner, altering patterns of resource allocation and energy expenditure, which, in turn, will affect reproductive success. Differential reproductive success resulting from the occurrence of physiological adaptations will have a direct impact on population structure, which will modify the interactions of those organisms with the rest of the ecological community, and thus the environment in which organisms live. Although the interaction among different levels of organization underlies research in Physiological Ecology, the actual integration of these levels is seldom explicit. For example, individual variation of physiological traits is rarely taken into account in ecophysiological studies. Instead population characteristics are reported, which might not capture the diversity of individual physiological responses.

The main project currently undergoing in my laboratory illustrates an application for the use of this framework. I hypothesize that environmental cues related with nutrient availability activate the expression of sirtuins, a family of protein de-acetylases which regulate cellular metabolic activity. This kind of control will be tissue-specific, resulting in the expression of phenotypic plasticity in organ size and activity: some organs will increase and some will decrease their growth rate and their metabolic rates, a process that, in turn, will elicit the adjustment of whole-organism energy expenditure. These changes in energy use will drive patterns of allocation of resources to different tasks (maintenance of homeostasis, organismal growth, storage of nutrients, performance and reproduction), which, ultimately, will affect reproductive success of individuals. We then attempt to identify those traits that might constitute physiological adaptations. Finally, we will model population structure based on the distribution of those potential physiological adaptations.