Meeting Abstract

96.4  Saturday, Jan. 7  Glucocorticoids, workload and fitness: the role of environmental context, plasticity and repeatability LOVE, Oliver/P*; BOURGEON, Sophie; MADLIGER, Christine; SEMENIUK, Christina/AD; WILLIAMS, Tony/D; University of Windsor; Norwegian Institute for Nature Research ; University of Windsor; University of Calgary; Simon Fraser University

There is growing debate as to whether (and if so how) baseline glucocorticoids (GCs) are linked to variation in organismal fitness (e.g., the “CORT-fitness hypothesis”). Baseline GCs show all the potential hallmarks of an adaptive trait: large intra-specific (individual) variation, an apparent genetic (heritable) component, and trait repeatability when measured under optimal or captive conditions. However, we lack basic information about the adaptive potential of baseline GCs, and paradigms such as the CORT-fitness hypothesis have not been tested within an environmental or individual quality context via experimental manipulations. We will discuss results of an experimental manipulation of environmental context during reproduction in a free-living bird designed to examine two key components of the CORT-fitness paradigm: i) the repeatability of baseline GCs across two within-year reproductive events, and ii) whether single point measures of GCs or plasticity in GCs during reproduction better predict fitness. Using our results, we will emphasize that environmental context can significantly influence the repeatability of baseline GCs and therefore alter the relationship between both static measures and plasticity of GCs and fitness.