Ecologia térmica e uso de abrigos artificiais por um lagarto ameaçado de extinção: estudo de caso de Liolaemus lutzae em uma área de restinga (Arraial do Cabo, RJ)

Abstract

The regulation of body temperature is one of the most important processes in the ecology of lizards, influencing physiological, morphological and behavioral processes. To keep their temperatures within a suitable range, these organisms obtain energy from environmental heat sources such as direct sunlight, air temperature or substrate temperature. Thus, habitat structure plays tend to play an important role in thermoregulation process. This study aimed to understand the processes influencing the thermoregulation the lizard Liolaemus lutzae which is threatened with extinction. Through the study of the thermal ecology of the population of Restinga da Praia Grande, Arraial do Cabo, Rio de Janeiro, we seek to understand how the species uses different microhabitats available in its environment and to assess to what extent this use can be influenced by the thermal characteristics of these microhabitats. The average body temperature of active individuals in the population was 31.3°C. Environmental temperatures (substrate and air) influenced the body temperature of the species in both seasons. We found no significant differences in mean body temperatures of females, males or juvenile in the rainy season and, in the dry season, the differences were considered negligible. During activity, the species used different types of anthropogenic materials in their habitat as shelter and as sites for thermorregulation. The microhabitats most frequently used both in the rainy and in the dry seasons were vegetation, plastic and pieces of wood. Adults used predominantly plastic, while juvenile used mainly vegetation. Models established to simulate the body of a lizard, placed under or within different types of materials used by L. lutzae for shelter sites for thermorregulation, recorded different temperatures both in the dry and in the wet, excepting wood and ceramics, since the temperatures of models under these microhabitats varied similarly. During the rainy season, the frequency of use of vegetation remained high even at the hottest times of the day when the models placed under this microhabitat reached temperatures above the range of the preferred temperature (Tpref) for the species (between 32.8 36.8 °C), while those models in wood and plastic reached values close to Tpref temperatures. The average body temperature of individuals under wood and plastic varied more consistently during the day than that of those individuals found in vegetation, but, in general, remained within the optimum range at peak times of activity of lizards. Liolaemus lutzae is currently listed as endangered species in the state (Rio de Janeiro), Country (Brazil) and Global (IUCN) listas of threatened soecies and has its distribution restricted to one of the most fragile and vulnerable environments in the country (Restinga habitats). Thus the study of their thermal environment can provide an important subsidy for conservation of the species and its habitat (Restinga) and allow a better understand of climate effcts on the species and on this coastal environment