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

Abstract

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.

Effects of different substrates on the sprint performance of lizards

“…A Panasonic SV200 camcorder set at 30framess -1 was mounted 61cm above the surface in all cases, and a segment of length 20cm was filmed, which related to a track distance of 0.45 to 0.65m. Previous studies on the speed performance of 10 species of Liolaemus showed that maximum speed was obtained at a distance between 0.45 and 0.60m from the starting point (Bonino et al, 2011). Additionally, the speed values obtained here are similar to those obtained by Bonino and colleagues, who used a racetrack with lightemitting diode sensors and an electronic timer.…”

“…Additionally, we explored whether there is a tradeoff between clinging ability and speed in these Liolaemini lizards using equivalent types of substrates. Considering the many previous results that relate morphology and ecological traits in the same lizard group (Jaksic et al, 1980;Schulte et al, 2004;Fernandez et al, 2011;Tulli et al, 2009;Tulli et al, 2011b;Bonino et al, 2011), we predicted that the morphological traits would be better explained by phylogeny. By contrast, because habitat structure might influence locomotor performance, it was reasonable to expect that lizard species would show better performance on a racetrack that mimics their own habitat structure.…”

“…For example, living in relatively open areas might be selective for highspeed sprinting over long distances; conversely, inhabiting highly structured habitats might favor short bursts of locomotion (Fuller et al, 2011). A considerable body of literature has focused on relationships between morphology and ecology (Miles and Ricklefs, 1984;Pounds, 1988;Herrel et al, 2002;Herrel et al, 2008;Herrel et al, 2011;Bickel and Losos, 2002;Irschick, 2002;Goodman et al, 2007;Goodman et al, 2008;Essner, 2007;Kohlsdorf et al, 2001;Kohlsdorf et al, 2004;Kohlsdorf et al, 2008;Marshall et al, 2008;McElroy et al, 2008;Collar et al, 2010;Grizante et al, 2010;Vanhooydonck et al, 2011) or between habitat use and performance (Losos, 1990a;Losos, 1990b;Irschick and Losos, 1999;Melville and Swain, 2000;Vanhooydonck et al, 2005;Mattingly and Jayne, 2004;Autumm et al, 2006;Goodman et al, 2008;Johnson et al, 2010;Bonino et al, 2011;Fuller et al, 2011). However, there are relatively few studies about how habitat structure might influence the relationships between morphology and ecology (e.g.…”

“…Thus, these species show a diversity in habitat usage, including generalized terrestrial as well as habitat specialists living on arboreal substrates, rock boulders (using the crevices or slipping underneath them) or sand (Halloy et al, 1998;Schulte et al, 2004;Tulli et al, 2009;Tulli et al, 2011a). Only two studies of Liolaemus species have considered information on running performance from a mechanistic point of view for Liolaemus (Fernandez et al, 2011;Bonino et al, 2011), but none so far has investigated the effect of surface or habitat structure on performance within an evolutionary context. Thus, we selected Liolaemus as our primary study group, and other Liolaemini and Leiosaurine species served as outgroups.…”

Climate, geographic distribution and Viviparity in Liolaemus (Reptilia; Squamata) species: when hypotheses need to be tested

“…Las especies de Liolaemus parecen estar adaptadas a temperaturas ambientales bajas (Cruz et al 2005;Rodríguez-Serrano et al 2009;Fernández et al 2011;Medina et al 2012;Moreno Azócar et al 2013), tanto por su relación con los valores medios de Tc como en los de TCmín (Cruz et al 2005;Bonino et al 2011, Moreno Azócar et al 2013). …”