Meeting Abstract
At its core, evolutionary endocrinology represents a synthesis between comparative endocrinology and evolutionary genetics. This synthesis can be viewed through the breeder’s equation, a cornerstone of quantitative genetics that, in univariate form, states that a population’s evolutionary response is the product of the heritability of a trait and selection on that trait (R = h2S). Under this framework, evolutionary endocrinologists have begun to quantify the heritability of, and the strength of selection on, a variety of hormonal phenotypes. With reference to our work in birds and lizards, we review theses studies while emphasizing the challenges of applying this framework to hormonal phenotypes that are inherently plastic and mediate adaptive responses to environmental variation. Next, we consider the untapped potential of evolutionary endocrinology as a framework for exploring multivariate versions of the breeder’s equation, with emphasis on the role of hormones in structuring genetic covariance. As an extension of the familiar concepts of phenotypic integration and hormonal pleiotropy, we illustrate how the hormonal milieu of an individual acts as a local environment for gene expression, thereby influencing the quantitative-genetic architecture of integrated, multivariate phenotypes. In particular, we show how classic hormonal manipulations and quantitative-genetic breeding designs can be integrated with next-generation transcriptomic surveys to link genotypes to phenotypes via hormonal regulation. We emphasize that hormones are more than mechanistic links in the translation of genotype to phenotype: they are interactive features of the evolutionary process, structuring the genetic variances and covariances that determine a population’s evolutionary response to selection.
