Análise do padrão de atividade e ecologia térmica do lagarto Tropidurus torquatus no sul do Brasil

Abstract

Lizards are model organisms in ecology, providing understanding of patterns and relationships between organisms and their environment. Tropidurus torquatus is a species with populations living in different habitats and under different environmental pressures. The objective of this study is evaluated thermal ecology and activity pattern of Tropidurus torquatus and this relation with environmental variables utilizing statistics methods. To answer questions regarding the activity pattern and thermal ecology, sighted individuals along transects were recorded and body temperature of animals captured manually checked. The time in activity was higher in summer (p <0.001) than in winter. In summer the animals began their activity sooner (p <0.001) and early return to shelters in winter (p <0.01). When seasons were analyzed separately only the photoperiod (r = 0.62 p = 0.01) and sunlight (r = 0.53, p = 0.03) were correlated with the period of activity in the summer and only sunlight (r = 0.85 p <0.01) and the substrate temperature (r = 0.58 p = 0.01) in winter. There is a higher proportion of animals exposed to sun at the beginning and at the end of the day in the summer and near midday in winter (p <0.01). The body temperatures ( ̅= 33.6 °C ± 2.86; n= 369 were correlated with the temperatures of the substrate (r = 0.58, p <0.01) and air (r = 0.57, p<0.01). There was no difference between the two populations (p = 0.23) and between sexes (F1, 359 = 0.32, p = 0.57) using the ambient temperatures as a covariate (p <0.01). The difference in the duration of the activity is due to the reduction of temperature, sunlight and photoperiod in winter. Despite the seasonality in the duration of the activity, the activity pattern is unimodal type, similar to other populations and other tropidurids. The data suggest that both historical factors and phenotypic plasticity are acting in southern populations of Tropidurus torquatus in environmental response.