Performance, behavior and offspring morphology may offset reproductive costs of male-typical ornamentation for female lizards

Females of sexually dimorphic species that bear male-typical secondary sexual traits, such as male ornaments, may incur costs. However, in some species, ornamented females can be found in high numbers, suggesting that they may experience benefits that offset these costs. Some female fence lizards (Sceloporus undulatus) possess blue badges that are similar to, but less dramatic than, those displayed by males during courtship and dominance contests. Females bearing these badges have reduced reproductive investment and are less desirable as mates, costs that are difficult to reconcile with the high prevalence of this trait (up to 95% of females) in some populations. To test the hypothesis that there are potential benefits associated with male-typical ornamentation in females, we compared fitness-relevant performance, behavior and morphology of ornamented and unornamented female fence lizards and their offspring. Ornamented females achieved faster sprinting speeds and had offspring that were more likely to flee from predatory attacks and had longer bodies; these traits are associated with higher survival in this species. These results suggest the presence of two female morphotypes that may be differentially favored under contrasting environmental conditions. Unornamented females appear to have a reproductive advantage that should be favored under low predation environments. By contrast, ornamented females have traits that would confer a fitness advantage in high-predation environments. This work suggests a potential mechanism maintaining male-typical female ornamentation in nature.