Physiological Consequences of Food Limitation for a Color Polymorphic Lizard: Are Coping Responses Morph-Specific?

Color polymorphism in animals often reflects discrete intraspecific variation in suites of traits linked with survival and reproductive success, as well as an ability to exploit diverse habitat types. Given those considerations, it has been hypothesized that color polymorphic species may be better able to withstand broad-scale environmental disturbances compared to monomorphic taxa. An assumption underlying this hypothesis is that morphs differ in their responses to the consequences of a disturbance. We test whether two color morphs of the Ornate Tree Lizard ( Urosaurus ornatus ) differ in their physiological responses to a likely outcome of a habitat disturbance, food limitation. We subjected blue and yellow morph U. ornatus to one of two feeding treatments (control [fed every other day] and food-limited [fed every five days]) and monitored their changes in body mass and stamina capacity for the next four weeks. We found that in general, food-limited males lost mass and had reduced stamina over time. Although yellow males had consistently greater stamina than blue males, the temporal patterns of change in stamina, as well as body mass, were not morph-specific. Our findings suggest that at least one aspect of a species' coping tactics, in terms of energy-allocation decisions, is similar for these two U. ornatus morphs. Despite this overlap, the consistently lower stamina capacity of blue males in this study, coupled with data from ongoing field work in our lab, suggest that this morph may nonetheless suffer greater long-term fitness costs than yellow males in disturbed environments.