Thermoregulation in Coastal Sand Dunes: Impacts of the Habitat Modification on the Wiegmann´s Lizard

Abstract

The notion of thermoregulation implies that organisms actively use behavioral and physiological adjustments to maintain body temperature (Tb) within a narrow range. Behavioral adjustments are the primary means that ectotherms like lizards use to regulate their Tb, of whom microhabitat selection is more important than postural adjustments. The structural properties of the habitat influence the capabilities of some lizards to thermoregulate efficiently, even many of the costs associated with thermoregulation can be reduced by inhabiting environments with environmental temperatures that are similar to their preferred Tb. Anyway, most of individuals acquire and maintain Tb by shuttling between different microhabitats where they can gain or lose heat. However, in places where the physiognomic structure of the native habitat has been modified by exotic vegetation the effects can be harmful, and some lizards must cope with a low thermal efficiency. In Argentina, the coastal sand dunes of the province of Buenos Aires have been planted whit acacia trees (Acacias pp) for stabilizing dunes and decorative purposes since the last 70 years. As a result, the structure of the native vegetation in some places has changed from open grasslands to areas covered with different degrees of a closed canopy, which reduces and deteriorates the thermal spectrum of the environment. The Wieggman´s lizard, Liolaemus wiegmannii, inhabits these coastal dunes using the vegetation cover of the semi fixed-dunes in natural and modified sites. This chapter presents the analysis of different aspects of the thermoregulation of this lizard (such as preferred and mean body temperatures, thermoregulatory efficiency, behavioral mechanisms, and thermal patch selection) in natural and modified grasslands, exploring how the structural alteration of native grasslands of coastal sand dunes affects thermoregulation of this species.