Physical and physiological performance adjust according to magnitude of an integrated immune challenge in the side-blotched lizard (Uta stansburiana)

Physical and physiological performance traits are constrained by their energetic costs, potentiating trade-offs when competing demands of the environment (internal, external) impinge upon concurrent investment. For reptiles, the costs of responding to internal challenges (e.g. infection, injury) can impede coping with external challenges (e.g. predator avoidance, foraging), and vice versa. Whether phenotypic shifts in performance occur may depend on not only challenge type and energetic state, but also challenge severity and response priority. To address how magnitude of an integrated immune challenge impacts both physical and physiological performance, comparisons of maximal sprint speed and rates of healing from wounds of discrete sizes (small, large) were made in male common side-blotched lizards (Uta stansburiana). Energy budget (i.e. food intake) and oxidative stress (i.e. free radicals versus antioxidant capacity) associated with performance investment were also compared among lizards by wound size. Findings herein reveal sprint speeds were not constrained overall when recovering from wounds of either size. Instead, relationships between wound healing and sprint speed deviate with wound size over time such that both are concurrently invested for small wounds and at a tradeoff for large wounds. Adjustments in performance according to the demands of an immune challenge may offset the associated energetic and oxidative costs. Nonetheless, greater wound size also led to decreases in both food intake and oxidative resistance, suggesting aspects of survival may become compromised if an immune challenge exceeds a certain magnitude.