Understanding the factors that determine a species’ range is a central objective in ecology and evolutionary biology. It also provides important information in predicting species distributions in response to environmental changes and future conservation. This thesis examined the effect of environmental factor, mainly on abiotic factors, on three Takydromus lizards living at different altitudinal ranges in Taiwan. These three Takydromus lizards are the high mountainous T. hsuehshanensis (> 1800m in altitude), T. formosanus (recently revised as T. viridipunctatus, < 1500m in altitude) and lowland T. stejnegeri (< 500m). This study had two main objectives: one was to investigate the difference in thermal physiology and its role on altitudinal distributions of these three species, another was focusing on the mountainous T. hsuehshanensis to investigate whether it was able to live well under the lowland environment. To achieve the first objective I analyzed three thermal physiological traits of these three species: the heat thermal tolerance, the cold thermal tolerance, and the sprint speed. To achieve the second objective I conducted a transplant experiment on the mountainous T. hsuehshanensis. I moved it to the semi-natural outdoor enclosures in lowland areas and recorded its growth and survival rates during one year period. In chapter 1, I investigated whether heat tolerance was a crucial factor for the altitudinal distributions of T. hsuehshanensis. T. formosanus and T. stejnegeri were served as comparative groups. I measured and compared their critical thermal maximum (CTMax) and survival rates under 3 fluctuating daily temperature treatments over a 3 month period. Two of the 3 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 the cool temperatures in mountain areas (C treatment). The results showed that (1) CTMax of T. hsuehshanensis was higher than the summer temperature in the lowland areas, but was not significantly lower than those of the other two lowland species, (2) T. hsuehshanensis survived the H and EH treatments for 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. I concluded that the heat tolerance of T. hsuehshanensis is not a crucial factor limiting its current altitudinal distribution. In chapter 2, I investigated whether cold tolerance was an important limiting factor for the current altitudinal distributions of two Takydromus lizards, T. formosanus and the lowland-dwelling T. stejnegeri in Taiwan. I measured their critical thermal minimum (CTMin) and 3-month survival rates in 4 cold treatments, and compared these with T. hsuehshanensis. The results indicated that (1) both the CTMin and prolonged cold tolerance were correlated with their upper limit of altitudinal distributions as predicted and (2) T. formosanus and T. stejnegeri had reasonable survival rates at temperatures that were lower than the underground temperature of high altitudinal areas. I concluded that although cold tolerance was correlated with altitudinal distribution, it is not a crucial factor limiting T. formosanus and T. stejnegeri in higher altitudes. In chapter 3, I investigated the impact of environmental temperature on altitudinal distributions of T. hsuehshanensis by examining its thermal sensitivity of locomotor performance. Its sprint speed was measured at nine body temperatures after two weeks acclimation at two different temperatures. The same measurement was performed on T. formosanus. The results indicated that (1) T. hsuehshanensis was capable of maintaining normal locomotor performance within a body temperature range approximating summer temperatures of lowland areas; (2) T. formosanus was able to run significantly faster than T. hsuehshanensis in body temperatures range of 20oC to 40 oC; (3) these two species did not differ in thermal sensitivity of locomotor performance; and (4) temperature acclimation did not affect the locomotor performance of these two species. I concluded that locomotor performance was not a factor limiting the distribution of T. hsuehshanensis to lowland areas. In chapter 4, I checked the survivorship and growth rate of T. hsuehshanensis in semi-natural enclosures in a lowland area during one year period. I provided them with plenty of water, food, and shelters, and removed/isolated the potential predators. The results indicated that (1) T. hsuehshanensis could maintain a reasonable survival rate at least within the first 6 months, (2) at the 9th and 12th month, the survivorship of T. hsuehshanensis declined to 41.9% and 19.3% respectively, which was significantly lower than those of the T. formosanus (80.6% at both the 9th and 12th month), and (3) in the summer T. hsuehshanensis was able to survive well and to increase their body weights; while in the winter it remained active but was not able to perform a normal shedding and was detected to have fester toes and eye disease. Compared to T. hsuehshanensis, T. formosanus did not shed their skin in the winter and had significantly less individuals having fester toes and eye diseases. According to these results, I concluded that the lowland area was not a suitable environment for T. hsuehshanensis to establish population in its recent state. I also inferred that the environment in winter had a negative effect on year-round successful survival of T. hsuehshanensis in lowland areas. However, since this experiment lasted for only one year, further investigations are needed to confirm this conclusion. In summery, I have demonstrated that thermal tolerances were not crucial physiological factors that limited the altitudinal distributions of these 3 species. The locomotion capacity of T. hsuehshanensis was not reduced in the temperatures approximating lowland temperatures. Further examination on other important traits will help to clarify the temperature effect on the altitudinal distributions of these three species. T. hsuehshanensis was not able to survive well in the outdoor enclosures in lowland areas, which may be due to the effects of climate or infective micro-organism in lowland area. Further investigations are needed to support my interpretation.