Christian Keith A, Griffiths Anthony D, Bedford Gavin S
School of Biological Sciences, Northern Territory University, 0909, Darwin, NT, Australia.
Oecologia. 1996 Apr;106(1):49-56. doi: 10.1007/BF00334406.
The frillneck lizard, Chlamydosaurus kingii, is a conspicuous component of the fauna of the wetdry tropics of northern Australia during the wet season, but it is rarely seen in the dry season. Previous studies have demonstrated that during the dry season the field metabolic rate (FMR) is only about one-quarter of the wet-season rate, and one factor involved in this seasonal drop is a change in the behavioural thermoregulation of the species such that lower body temperatures (T s) are selected during dry-season days. Here we examine other factors that could be responsible for the seasonal change in FMR: standard metabolic rates (SMR) and activity. Samples from stomach flushing revealed that the lizards in the dry season continued to feed, but the volume of food was half as much as in the wet season. SMR in the laboratory was 30% less in the dry season. During the dry season, the energy expended by the lizards is 60.4 kJ kg day less than during the wet season. Combining laboratory and field data, we determined the relative contribution of the factors involved in this energy savings: 10% can be attributed to lower nighttime T , 12% is attributable to lower daytime T , 12% is attributable to decreased metabolism, and the remaining 66% is attributable to other activities (including e.g. locomotion, reproductive costs, digestion). Calculations indicate that if FMR did not drop in the dry season the lizards would not survive on the observed food intake during this season. Seasonal analysis of blood plasma and urine indicated an accumulation of some electrolytes during the dry season suggesting modest levels of water stress.
褶伞蜥（Chlamydosaurus kingii）是澳大利亚北部干湿季热带地区雨季动物群的显著组成部分，但在旱季却很少见。先前的研究表明，在旱季，其野外代谢率（FMR）仅约为雨季的四分之一，导致这种季节性下降的一个因素是该物种行为体温调节的变化，即旱季白天选择较低的体温（Ts）。在此，我们研究了可能导致FMR季节性变化的其他因素：标准代谢率（SMR）和活动。洗胃样本显示，旱季的蜥蜴仍在进食，但食量仅为雨季的一半。实验室中的SMR在旱季降低了30%。在旱季，蜥蜴消耗的能量比雨季少60.4千焦/千克/天。结合实验室和野外数据，我们确定了这种能量节省所涉及因素的相对贡献：10%可归因于夜间较低的体温，12%归因于白天较低的体温，12%归因于新陈代谢降低，其余66%归因于其他活动（包括例如运动、繁殖成本、消化）。计算表明，如果旱季FMR不下降，蜥蜴将无法依靠该季节观察到的食物摄入量生存。血浆和尿液的季节性分析表明，旱季某些电解质会积累，这表明存在一定程度的水分胁迫。
