Influence of body temperature on food assimilation and locomotor performance in white-striped grass lizards, Takydromus wolteri (Lacertidae)

Abstract

Influence of body temperature on food assimilation and locomotor performance was studied in adult white-striped grass lizards ( Takydromus wolteri) from a population in Chuzhou (Anhui, Eastern China). Food passage time dramatically decreased with increase in body temperature within the range from 26°C to 34°C, and then nearly levelled at higher body temperatures. Lizards overall gained net mass at 26°C, 28°C and 30°C and lost mass at 32°C and 34°C. Daily production of faeces (mass-specific) was affected by body temperature and, when influence of variation in the total food energy intake was removed by an ANCOVA, lizards at 26°C were found to produce faeces that contained significantly lower energy as compared with those at higher body temperatures. The total energy of urates was affected by the total food energy intake, but an ANCOVA with the total food energy intake as the covariate showed that lizards at different body temperatures did not produce urates that differed in energy. Within the temperature range considered, daily production of urates (mass-specific), apparent digestive coefficient (ADC) and assimilation efficiency (AE) were not affected by body temperature, although both ADC and AE were apparently greater in lizards at 26°C. Both locomotor stamina and sprint speed increased with increase in body temperature within the range from 18°C to 30°C, and then decreased at higher temperatures. Inter-individual differences were a significant source of variation in locomotor performance. Except for ADC and AE, all traits examined were significantly affected by body temperature, although thermal sensitivities differed considerably among traits. Within the body temperature range considered, 26°C was the most suitable body temperature for somatic tissue growth, and 30°C was an optimal body temperature for locomotor performance.