Running in cold weather: morphology, thermal biology, and performance in the southernmost lizard clade in the world (Liolaemus lineomaculatus section: Liolaemini: Iguania).

The integration or coadaptation of morphological, physiological, and behavioral traits is represented by whole-organism performance traits such as locomotion or bite force. Additionally, maximum sprint speed is a good indicator of whole-organism performance capacity as variation in sprinting ability can affect survival. We studied thermal biology, morphology, and locomotor performance in a clade of Liolaemus lizards that occurs in the Patagonian steppe and plateaus, a type of habitat characterized by its harsh cold climate. Liolaemus of the lineomaculatus section display a complex mixture of conservative and flexible traits. The phylogenetically informed analyses of these ten Liolaemus species show little coevolution of their thermal traits (only preferred and optimum temperatures were correlated). With regard to performance, maximum speed was positively correlated with optimum temperature. Body size and morphology influenced locomotor performance. Hindlimbs are key for maximal speed, but forelimb length was a better predictor for sustained speed (i.e. average speed over a total distance of 1.2 m). Finally, sustained speed differed among species with different diets, with herbivores running on average faster over a long distance than omnivores.