Meeting Abstract
Hormones play a central role in coordinating behavior and physiology, responding to changes in the environment, and promoting transitions among stages of the life cycle. Despite their importance, and the large amount of available data on circulating hormone levels, we still know remarkably little about how and why circulating hormone levels differ. Hormone concentrations show striking variability at all taxonomic scales, but to test large-scale hypotheses on hormonal evolution, a comprehensive database of hormonal data is needed. Here, we introduce HormoneBase, a publicly-available database of published measures of testosterone, 11-ketotestosterone, corticosterone, and cortisol in free-living, adult vertebrates. HormoneBase includes over 6,300 measures of hormones from 431 species, reported in 658 publications from 1967 to 2015. Using this database, we test for abiotic and biotic predictors of mean testosterone or 11-ketotesosterone levels, as well as variability in hormone levels, across all vertebrate groups: fishes, amphibians, reptiles, birds, and mammals. Variables include latitude, elevation, and breeding season length, as well as numerous life-history and social-organization variables. We also looked specifically within fishes to determine if patterns were similar when considering 11-ketotestosterone. Finally, we determined whether baseline glucocorticoid levels were related to androgen levels across vertebrates. While these analyses have been performed in specific taxonomic groups separately, our analyses represent the first vertebrate-wide analysis of androgen levels and provide important insight into the evolution of vertebrate endocrine function.
