Meeting Abstract
If organisms are to persist in the face of climate change, they must be able to deal not only with increasing temperatures, but also greater climatic variation. One of the primary ways animals cope with environmental change is through phenotypic plasticity, the ability to respond to environmental cues through phenotypic adjustment. In birds, the hypothalamic–pituitary–adrenal (HPA) axis allows individuals to rapidly adjust their responses to environmental change. Despite much work exploring HPA function under different environmental conditions, we still lack a thorough understanding of how the HPA axis has evolved in species living in naturally variable and unpredictable environments. Using superb starlings (Lamprotornis superbus), which inhabit a range of East African environments where rainfall varies within and among years, I will explore the molecular mechanisms that underlie plasticity in the HPA axis. First, I will show how annual variation in rainfall during development influences plasticity in the form of DNA methylation of the glucocorticoid receptor, which in turn affects their fitness later in life. Next, I will explore how patterns of DNA methylation in other HPA-related genes, as well as across the entire starling genome, vary with rainfall during development. Finally, I will compare patterns of DNA methylation across the genome from birds collected along an ecological gradient spanning hundreds of kilometers that varies in the degree of rainfall variability and predictability. Together, these studies demonstrate how environmental uncertainty shapes the HPA axis, allowing organisms to respond plastically to environmental change and maximize their fitness in unpredictable environments.
