The Comparison Of Thermoregulation Between Phrynocephalus Erythrurus And Phrynocephalus Przewalskii

Temperature is an important factor affecting physiological activity of ectotherm. In this study, the Phrynocephalus przewalskii and Phrynocephalus erythrurus located in desert regions of Minqin, Gansu province and in a high altitude regions WuDaoliang, Qinhai province, respectively, were used to study thermoregulation and pressure of environmental temperature, as well as physiological indices about thermoregulation.The P. przewalskii and P. erythrurus are small toad-headed sand lizards endemic to China, which inhabit desert and semi-desert region ranging from1000to1700m and region ranging from4500to5300m respectively. These different environments may cause different survival strategy of lizards. To explore physiological adaption mechanism of P. erythrurus living in highland, we conducted a study in both field and laboratory. In the field, we measured the body temperature of lizards, the time of capture, and the body temperature of simulative lizards without behavioural and physiological thermoregulation. In the laboratory, a temperature gradient ranging from20℃to50℃was built to test preferred body temperature at10:00h,13:00h and16:00h every day. Finally, the heating and cooling rate, heart rate, and limited tolerance temperature were tested in the laboratory to analysis physiological thermoregulation of two species of lizards.The results showed that firstly, selected body temperature of P. erythrurus was significantly lower than that of P. przewalskii. Then, the temperature of P. erythrurus was more relative with the set-point range than that of P. przewalskii in the field. Thirdly, heating rate of P. erythrurus was markedly higher than that of P. przewalskii, however, they had similar cooling rate. Fourthly, heart-rate hysteresis appeared during these two species, and there was not difference in heart rate at any given temperature between these two species. Finally, limited tolerance temperatures of P. erythrurus were higher signally than that of P. przewalskii. Thus, the thermoregulated ability of P. erythrurus is more stronger than that of P. przewalskii. The rate of heating of P. erythrurus is faster than that of P. przewalskii, which maybe not caused by difference of heart rate in this study.