CONICET | Buscador de Institutos y Recursos Humanos

In environments where the temperature periodically drops lower than zero, some lizards remarkably endure. Behaviorally, lizards can find microsites for overwintering where temperatures do not drop as much as air temperature. Physiologically, they can alter their biochemical balance to tolerate freezing or avoid it by supercooling. We evaluated the cold hardiness of a population of Liolaemus pictus argentinus Duméril and Bibron, 1837 in the mountains of Esquel (Patagonia Argentina) during autumn. Additionally, we assessed the 46 thermal quality (in Degree-days) of potential refuges in a mid-elevation forest (1100 m a.s.l.) and in the high-Andean steppe (1400 m a.s.l.). We analyzed the role of urea, glucose, total proteins and albumin as possible cryoprotectants, comparing a group of lizards gradually exposed to temperatures lower than 0°C with a control group maintained at room temperature. However, we found no evidence supporting the presence of freeze tolerance or supercooling mechanisms in this species related to the analyzed metabolites. Instead, the low frequency of Degree-days below 0°C and temperatures never lower than -3° C in potential refuges suggest that L. pictus argentinus might avoid physiological investments (such as supercooling and freeze tolerance) by behaviorally selecting appropriate refuges to overcome cold environmental temperatures.