RAPID: Using an extreme climatological event to inform the evolutionary systems biology of thermogenic performance in deer mice.

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Two of the primary goals of evolutionary and ecological physiology are understand the mechanisms of physiological performance, and to assess the ecological consequences of individual variation in physiological traits. In this study, the PI will take advantage of a recent extreme cold weather event, the southward incursion of the polar vortex during the winter of 2013-2014, to extend his ongoing studies of the mechanistic underpinnings of thermogenic performance in high- and low-elevation populations of deer mice (Peromyscus maniculatus). The PI's current research efforts (recently recommend for funding by NSF - IOS 1354934) are aimed at applying systems-biology approaches to develop and parameterize hierarchical computational models of the adaptive modification aerobic thermogenic capacity. In this study, he will complement these mechanistic insights with direct estimates of the strength of natural selection acting on various traits that influence whole-organism thermogenic performance. The brutal winter of 2013/2014 represents an extreme selective episode acting on thermogenic performance in small, winter-active endotherms like deer mice. As a result, the researchers have a unique opportunity to evaluate the strength of natural selection acting on traits that influence whole-organism thermogenic performance in the wild, and to directly incorporate data on selection intensities into their integrative analysis of the evolution of thermogenic performance. This study will provide key insights into the mechanisms underlying rapid phenotypic and evolutionary responses to severe climatic events.Although many studies have documented phenotypic changes in response to putative selective episodes, none have used detailed mechanistic insights to predict which phenotypic traits are likely to be the targets of natural selection on this scale. The PIs ongoing mechanistic analysis of thermogenic performance will allow him to identify phenotypic and regulatory changes that are most likely to influence O2 flux and overall thermogenic capacity, while the work proposed in this study will allow the researchers to make direct connections between the intensity of selection acting on a trait and quantitative analysis of its regulatory control over pathway flux. The researchers will use shifts in phenotypic trait means to formally estimate selection differentials acting various subordinate traits and regulatory network states that influence thermogenic performance under hypoxia. The combination of these lab and field studies will make important strides toward an integrated evolutionary systems biology framework for understanding adaptive variation in complex physiological traits.