Meeting Abstract
Phenotypic flexibility allows organisms to reversibly alter their phenotypes to match the demands of temporally fluctuating selective pressures in seasonal environments. While the adaptive value of properly matching phenotypes to prevailing environmental conditions is clear, the physiological and regulatory mechanisms that underlie seasonal changes in phenotype are not. Because phenotypic flexibility is mediated, at least in part, by changes in gene regulation, we conducted a series of comparative studies to identify transcriptomic changes associated with seasonal shifts in thermogenic performance in three species of resident North American songbirds. In this talk, I will synthesize the results of these studies, which include surveys of seasonal transcriptomic changes in free-ranging, wild birds and acclimation experiments on captive individuals. These studies point to three main insights about the regulatory changes that contribute to seasonal phenotypic flexibility. First, co-expression network analyses revealed transcriptional modules of co-regulated genes that were highly conserved across species. Second, while only a subset of the transcriptional modules were associated with higher-level physiological traits and showed seasonal changes in expression, these associations were also conserved across species. Finally, acclimation studies of captive Dark-eyed Juncos revealed that most of these seasonally flexible and phenotype-associated modules respond to cold exposure, rather than to changes in photoperiod. Together, these studies provide the first comprehensive overview of potential common regulatory mechanisms underlying seasonally flexible phenotypes in birds.
