Termorregulación de la lagartija Liolaemus chacoensis (Squamata: Liolaemidae) durante su ciclo reproductivo, en el Chaco occidental, Argentina

Abstract

Regulation of body temperature in lizards plays a key role in the survival of species. Their physiological condition, in reference to their dependence on the ambient temperature makes them an excellent study model. Also, changes in the reproductive cycle cause changes in thermophysiological parameters. This study is the first to address the relationship of thermoregulation with reproductive activity and sex, for a species of Liolaemus from the Chaco ecoregion. The aim of this work was to determine how the reproductive, recruitment and post-reproductive periods influences, as well as the effect of sex and snout-vent length on the thermoregulation of Liolaemus chacoensis. Individuals were captured by hand in the Southern sector of Valle Fertil, San Juan province, Argentina. A total of 44 individuals were captured during the months of November 2014, February 2015 and March 2015. Body (Tb), substrate (Ts) and air (Ta) temperatures were recorded. Also, biophysical models were used to record operative temperatures. Later selected temperatures (Tsel) were evaluated at the laboratory. Finally, thermoregulatory efficiency index was calculated. Results indicated that L. chacoensis Tb was positively related to Ta, presenting a heliothermic behavior that was maintained during periods and sex. Also, Tb was higher in reproductive and recruitment periods than in post-reproductive period. In particular, only sex had an effect on Tsel, however for the interquartile range of Tsel both the period of reproductive cycle and sex had an effect. The thermoregulatory efficiency index indicated that L. chacoensis is an absolute thermoconformist. However, in the reproductive period both males and females change towards active thermoregulation. These results show that thermophysiological parameters vary in different periods of reproductive cycle and the active microsite selection would be a mechanism in maintenance of body temperature of this species.