Reproductive success, apparent survival, and ventral blue coloration in male prairie lizards (Sceloporus consobrinus)

Abstract

AbstractColoration can evolve in response to selection targeting colorful traits that affect survival or reproductive success. Trait covariation can complicate evolutionary dynamics when selection on covarying traits acts antagonistically. In prairie lizards (Sceloporus consobrinus), males exhibit blue ventral patches that are reduced in females. The development of ventral coloration corresponds with increases of circulating testosterone at sexual maturity. Previous work has illustrated that testosterone and coloration covary, such that individuals with higher testosterone have bluer patches. However, testosterone is known to increase mortality in many organisms, including Sceloporus, so selection against high testosterone can lead to indirect selection against bluer males. While previous work has suggested that patch coloration does not affect fitness, this has not yet been explicitly tested using estimates of survival and reproductive success. Here, we quantify patch coloration, apparent survival, encounter probability, and reproductive success in a wild population of male prairie lizards to assess the role of patch color variation on fitness. Specifically, we tested how patch coloration affects survival and reproductive success across 2 years. We found that none of the patch phenotypes we measured covaried with fitness, suggesting that neither natural nor sexual selection act, or act very weakly, on patch morphology. We found evidence of sexual selection on body size, such that larger males sired more offspring, likely through increased activity. However, this result was inconsistent, as it was only found in one year. Interestingly, we found that, in both years, bluer males were more likely to sire at least one offspring, suggesting some role of patch coloration in reproduction, although we cannot detect what that role may be. Overall, our study suggests that neither apparent survival nor reproductive success is strong drivers of the evolution of ventral coloration in S. consobrinus.