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In this dissertation, a nocturnal lizard Gekko japonicus was used as a model animal to study synthetically:(1) field active body temperature and thermoregulation;(2)basic traits of thermal biology, including preferred body temperature, thermal dependent locomotor performance;(3)thermoregulatory mechanism, including physiological and behavioral thermoregulation.The main results and conclusions are summarized as following:1. Field active body temperature and thermoregulationField active body temperatures did not differ among geckos of different ages. Between-sex difference in the trait was also not evident. There was seasonal variation in field active body temperatures. The average field active body temperatures in July were higher than those in May and September.During nocturnal activity, the effectiveness of thermoregulation in gravid females was higher than that in males, nongravid females and juveniles.2. Basic traits of thermal biology in Gekko japonicusPreferred body temperatures differed evidently in different seasons, but not among different geographic populations. Preferred body temperatures in July were higher than in those in May and October.Preferred body temperatures of the geckos showed between-sex difference in May, but not in June and October. Preferred body temperatures of females were higher than those in males.In June, preferred body temperatures differed among geckos of different ages, furthermore, preferred body temperatures of gravid females and juveniles were higher than those in nongravid females and males.There was no among-location or between-sex difference in critical thermal maximum and critical thermal minimum of geckos. The curves of CTmax and CTmin showed that CTmax of the gecko was about41.9℃, and the CTmin was about-5.8℃.Locomotor performance was profoundly affected by body temperature of the geckos:average speed increased with the increase of body temperatures from15℃to34℃, and decreased when the temperature was higher than34℃. There were no among-age or between-sex differences in average speed. The locomotor performance of females was significantly affected by their body mass and the slope of race track.3. Thermoregulatory mechanismPhysiological thermoregulation mechanismBody temperature increased with the increase of ambient temperatures, and decreased slightly when the ambient temperature was higher than31℃, while increased a little when the ambient temperature was lower than18℃. Behavioral thermoregulation mechanismHeat transmission mode(heliothermic patch vs thigmothermic patch) did not influence heating rates and the selection of pathes for heating, but operatical temperature affected observably on heating rates.Geckos were able to actively explore suitable thermal environments. Body temperatures of geckos decreased rapidly without heating, and they were inclined to move to warming treat-site.Both photoperiod and the position of light source influenced the diel cycle of thermal selection. The position of light source also significantly affected mean body temperature. Photoperiod and the position of light source were important both as separate and conjunctional factors influencing behavioral thermoregulation.