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

Abstract

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.

Honest signals and sexual conflict: Female lizards carry undesirable indicators of quality

“…Among female S . undulatus , a signaling function of rudimentary badges is even less clear, as few fitness benefits have been associated with the presence of badges (Assis et al., 2018). In fact, females bearing residual ornaments appear to incur costs: laboratory mate choice trials indicate that males were more likely to court unornamented females, and ornamented females had lower reproductive output (Swierk & Langkilde, 2013).…”

Plastic sexual ornaments: Assessing temperature effects on color metrics in a color-changing reptile

“…Moreover, variation in color appears to be fitness-relevant for this species: males with more saturated badges are more likely to be larger-bodied [31], and males with larger badges are preferred by females [32]. On the other hand, females exhibiting color are less preferred by males [30], but achieve faster running speeds and have offspring that evade predatory attacks more often [33].…”

Fitness Costs of Maternal Ornaments and Prenatal Corticosterone Manifest as Reduced Offspring Survival and Sexual Ornament Expression

“…Females have badges that lack the melanin pigmentation seen in males and consequently show a fainter (less saturated) blue ( 28 ). The fitness consequences of ornamentation in female fence lizards is still ambiguous, with studies linking it to costs ( 25 , 29 ) and benefits ( 30 ). Further, the size and saturation of these color patches are co-regulated by individual condition and physiology, with testosterone (T), dihydrotestosterone (DHT), and corticosterone (CORT) playing important roles ( 27 , 31 , 32 ).…”

“…studies linking it to costs (25,29) and benefits (30). Further, the size and saturation of these color patches are co-regulated by individual condition and physiology, with testosterone (T), dihydrotestosterone (DHT), and corticosterone (CORT) playing important roles (27,31,32).…”