Meeting Abstract
As signaling molecules, steroids can inform the body of impending changes in energetic state and facilitate a suite of metabolic, physiological and behavioral effects. Their vital roles in reproduction, stress and behavior means they are well-studied in both clinical and comparative disciplines, resulting in an enormous of data available comparing steroids across ranges of energetic challenges and measures. Traditionally, the different steroid classes have been associated with well-defined energetic effects, but a literature survey demonstrates highly variable and often contradicting results that may or may not support these roles. Thus aligning the traditional views relating energy and steroid functions have made developing a coherent framework difficult. I conducted an in-depth systematic review and meta-analysis of the comparative literature that relates steroids and energy (e.g., fasting, caloric restriction, and body condition). This review has demonstrated a significant discordance between: 1) manipulative studies and correlative research; 2) field and lab studies; 3) endotherms and ectotherms; 4) studies relating steroid levels to changes in body mass and those with changes in metabolic biomarkers; and 5) studies relating body condition with across varying steroid concentrations. Interestingly, mapping the effect sizes of energetic challenges against the variation in a respective steroid’s concentration reveals a robust relationship that is only apparent beyond an inflection point. This suggests only steroids that exhibit a wide range of variation in concentrations within a population of interest will exhibit the traditionally defined energetic effect of steroids. I propose a new framework for investigating the relationship between steroids and energy that accounts for population-level variation in steroid concentration.
