Molecular regulation of adiposity in a migrant, the gray catbird (1100.1)

Abstract

Prior to their migration, birds make physiological and behavioral adjustments to quickly accumulate fat stores to fuel their journey. The majority of these fat stores are utilized during their long‐distance flights. However, birds often complete vernal migrations with residual fat, which may be detrimental due to impaired flight behavior and increased predation risk, thus return to lean body composition is also rapid. This need for swift and substantial changes in a bird’s physiology marks migration as a unique life history stage emphasizing phenotypic flexibility, defined as intra‐individual and reversible phenotypic transformations. Specific mechanisms directing stage transitions of adiposity in migrating birds are largely unknown. This study aims to characterize the role of peroxisome proliferator‐activated receptors (PPARs) in migratory adiposity of the gray catbird (Dumetella carolinensis). PPARs are a family of nuclear receptors involved in mammalian energy metabolism and are highly conserved in our study species. We find evidence of PPAR involvement in migratory adiposity with a coordinated increased rate of glycerol release from adipose tissue, a downstream PPAR process, during periods of migration compared to non‐migratory stages. These data support further investigation into PPAR target gene expression experiments, and advance our understanding of the regulation of stage transitions associated with migratory adiposity.