Meeting Abstract
Rosemary Knapp’s research contributions emphasize the importance of considering individual life history stage and strategy when seeking to understand endocrine traits. This perspective has been central in clarifying the role of endocrine signals in regulating complex life history traits, and for understanding variation among individuals in responses to the same signals. In essence, this work placed the endocrine phenotype into an ecological and evolutionary context, and recognized that optimal endocrine phenotypes differ not only among the sexes, but also within sexes, among individuals with alternative reproductive tactics. Here, we extend this view to consider variation among individuals, rather than among morphs. If individuals express near-optimal endocrine phenotypes, well matched to their context, we predict that manipulations of these phenotypes (e.g., through hormone implants) should generally compromise fitness. We use a meta-analysis of hormone manipulation studies to test this prediction, and find some support for it, along with interesting sources of variation. Effects of hormone manipulations on fitness varied depending on the sex of individuals being manipulated, as well as on the metric used to estimate fitness. These findings reinforce the importance of understanding individual life history and environmental context when we seek to understand how selection has shaped, and is shaping, endocrine traits.
