Meeting Abstract
Organisms maintain dynamic regulatory systems that can confer the flexibility to reversibly match their phenotype(s) to fluctuating environmental conditions. This process often involves the dramatic modification of multiple subordinate traits. However, the relative influence of these component traits on whole-organism performance is poorly understood in natural systems. As a case study, we explore the contribution of subordinate phenotypes to avian body temperature regulation in the cold by combining assays of gene expression, tissue-level- and whole-animal physiology of Dark-eyed Juncos (Junco hyemalis) exposed to controlled temperatures. This work indicates that organismal performance is disproportionally influenced by a few subordinate traits and reveals an undocumented mechanism of avian thermoregulation. We then ask—Do populations within this geographically widespread species vary in their degree of flexibility? To address this, we replicated this approach across five additional Junco populations that vary in the natural thermal regimes they experience and interpret these patterns in light of historical demographic processes. Our results shed light on the mechanisms underlying avian body temperature regulation and the ability of natural populations to respond to seasonal environmental fluctuations.
