Heat tolerance and altitudinal distribution of a mountainous lizard, Takydromus hsuehshanensis, in Taiwan

1.We investigated whether heat tolerance has a crucial impact on the altitudinal distribution of a high-altitude lizard, Takydromus hsuehshanensis (>1800 m altitude).2.We measured and compared its heat tolerance with that of another two lowland species. Heat tolerance measurement included critical thermal maximum (CTMax) and survival rates under three fluctuating daily temperature treatments over a 3-month period. Two of the three temperature treatments, the extremely high temperature (EH treatment) and the average temperature (H treatment), were set to approximate lowland summer temperatures. The third one was set to approximate cool temperature in mountain areas (C treatment).3.Our results showed that (1) CTMax of T. hsuehshanensis was higher than the summer temperature in the lowland areas, and not significantly lower than that of two other lowland species, (2) T. hsuehshanensis survived the H and EH treatments over a 3-month period and its survival rate was not significantly lower than that of the other two lowland species. Therefore, T. hsuehshanensis was not only able to tolerate high temperatures mimicking lowland areas for a short period of time, but also for a much longer period of time.4.We conclude that the heat tolerance of T. hsuehshanensis is not a crucial factor limiting its current altitudinal distribution.