Vol. 46 No. 5, 2007

Thermal Tolerance and Altitudinal Distribution of Three Trimeresurus Snakes (Viperidae: Crotalinae) in Taiwan

Szu-Mien Huang, Shu-Ping Huang, Yi-Huei Chen, and Ming-Chung Tu*

Department of Life Science, National Taiwan Normal University, 88 Ting-Chow Rd., Sec. 4, Taipei 116, Taiwan

Szu-Mien Huang, Shu-Ping Huang, Yi-Huei Chen, and Ming-Chung Tu (2007) We measured and compared the acute thermal tolerances of a high-altitude pit viper, Trimeresurus gracilis, with that of its lowland congeners, T. mucrosquamatus and T. s. stejnegeri, to test whether their thermal tolerances are limiting factors determining their altitudinal distributions. The critical body temperatures, both the summer critical thermal maximum (CTMax) and the winter critical thermal minimum (CTMin), of these 3 species were measured after 2 wk of acclimation at 3 temperature regimes (10, 20, and 30°C). We discovered that (1) both the CTMin and CTMax of these 3 Trimeresurus snakes increased with increasing acclimation temperatures; (2) the lowest CTMin values of T. gracilis and T. mucrosquamatus did not significantly differ from each other, and both of them were significantly higher than that of T. s. stejnegeri; and (3) the CTMax values of these 3 Trimeresurus snakes did not significantly differ from each other. Overall, we did not find a clear relationship between acute thermal tolerances and altitudinal distributions of these 3 Trimeresurus species; hence, their acute thermal tolerances should not be limiting factors in determining their altitudinal distributions.

Key words: Pit viper, Critical thermal maximum, Critical thermal minimum, altitude, Temperature.

*Correspondence: Tel: 886-2-29333149. Fax: 886-2-29312904. E-mail:biofv026@ntnu.edu.tw