The evolution of sexually selected traits and antagonistic androgen expression in actinopterygiian fishes.

Many sexually selected traits in male fishes are controlled by testosterone. Directional selection for male ornaments could theoretically increase male testosterone levels over evolutionary timescales, and when genetically correlated, female testosterone levels as well. Because of the negative fitness consequences of high testosterone, it is plausible that female choice for sexually selected traits in males results in decreased female reproductive fitness. I used comparative analysis to examine the association between male peak testosterone expression and sexually selected ornaments. I also tested for genetic correlation between male and female androgen levels. The presence of sexually selected traits in males was significantly correlated with increased peak androgen levels in males as well as females, and female testosterone levels were significantly correlated with male peak testosterone titers, although the slope was only marginally <1. This suggests that selection to decouple high male and female testosterone levels is either weak or otherwise ineffective.