Color as a signal: The relationship between coloration and morphology in male eastern fence lizards, sceloporus undulatus

Color is used in social signaling by many species. Male Eastern Fence Lizards, Sceloporus undulatus, possess sex-specific dorsal and ventral coloration, including vivid blue badges on their throat and abdomen, which they behaviorally display to conspecifics. The presence of abdominal badges serves as a signal of an individual's sex, but the significance of badge and integument coloration for signaling fitness traits is unknown. We tested for associations between coloration (color of the dorsal surface, chest, and abdominal and throat badges, as well as relative badge size) and a range of fitness-relevant morphological traits (body size and condition, tail and hind-limb length, and head size) in male Eastern Fence Lizards from two sites. Larger males have darker colored abdominal badges and relatively larger abdominal and throat badges. Males with longer tails and wider heads have darker dorsal coloration, and there is a correlation between head length and the color of the black abdominal badges, but this is not consistent between sites. Adults also have darker chest and dorsal coloration than do juveniles. These relationships suggest that S. undulatus color may signal competitive ability to male opponents. However, if this were the case, we would expect body condition and limb length, morphological measures that are tightly correlated with these fitness traits, to also correlate with coloration. This was not evident from our data. Therefore, despite significant variation in coloration of male S. undulatus, it is unlikely to reflect fitness associated with the traits measured in this study.