The selective pressures exerted by predation can have considerable influence on the behavior of prey species across a wide range of taxa. Within a species, this force may differ between the sexes, leading to sex‐specific behavioral responses to predators. We tested whether the black spiny‐tailed iguana Ctenosaura similis is able to use auditory cues to detect an avian predator and whether antipredator responses differ in a sex‐dependent fashion. We conducted behavioral assays in which a food item was used as bait while iguanas were subjected to a recording of a Harris's hawk or white noise as a control. We found that a significantly greater percentage of individuals of either sex responded to the hawk call than to the white noise. We also found that a significantly greater percentage of females than males responded to either sound. These results suggest that not only do black spiny‐tailed iguanas incorporate auditory cues into predator detection, but that antipredator behavioral responses differ between the sexes as well. Such sex‐specific behaviors can be attributed to morphological and endocrine differences between male and female iguanas. These findings may also lend insight into how behavior can influence the evolution of sexual dimorphism within a species.

In many species, sexually selected combat and display traits can confer dramatic fitness benefits to males by aiding in mate acquisition, so individuals maximally invest energy into their growth and maintenance. Such traits are deemed condition-dependent, as the energy that is available for investment depends on the health and condition of the individual. Condition dependence is present in a wide range of traits across many taxa, but the extent to which condition dependence varies among shared traits in closely related species is poorly understood. We tested for condition dependence in two Anolis lizards, the ground anole (Anolis humilis) and the slender anole (Anolis limifrons). Specifically, we measured dewlap area, jaw length, jaw width, and sprint speed, and then regressed one of two indices of body condition on each of these traits for both species. We found that dewlap area and jaw width exhibited condition dependence in ground anoles, but not in slender anoles. Sprint speed and jaw length were not condition-dependent in either species. The presence of condition dependence in ground anoles, but not slender anoles, implies evolutionary liability in the condition dependence of shared traits. Additionally, the fact that condition dependence was only detected in ground anoles, which have a greater relative dewlap size, suggests a potential role for signal evolution or strength of sexual selection in the evolution of condition dependence. Finally, our research suggests that variation in condition dependence of sexually selected traits could have implications for the evolution of dewlap diversity among Anolis species.