Testing the Pace-of-Life Syndrome in the Tree Lizard, Urosaurus ornatus

Abstract The pace-of-life syndrome (POLS) describes covariation between behavioral, physiological, and in some instances thermal traits. The POLS predicts that bolder, more exploratory individuals should have higher metabolic rates, higher physiological performance, and prefer and perform better at high temperatures. Evidence supporting the POLS has been mixed. The goal of this study was to test the POLS in the color polymorphic tree lizard (Urosaurus ornatus) by comparing behavioral, thermal, and physiological performance traits, among all individuals, between the sexes, and among color morphs. We measured behavioral traits using laboratory-based estimates of boldness and exploration, thermal preference traits using a thermal gradient, and used stamina as a measure of locomotor performance. We described the patterns of covariation among the physiological, behavioral, and thermal traits using a principal component analysis. Bolder lizards were more exploratory, but selected cooler body temperatures, which contradicts the relationship predicted by the POLS. We also found that stamina was unrelated to either behavioral or thermal traits. Only boldness and exploration differed among the color morphs: blue and yellow/blue throated males were more exploratory than yellow males and yellow/blue males were bolder than yellow and orange/yellow males. Our results provide little support for the POLS in tree lizards. This study emphasizes the importance of not overgeneralizing the prevalence of the POLS and that in some populations, local conditions and selection pressures may play a larger role in trait correlations than suites of generalized traits.