Genoud Michel
Department of Ecology and Evolution, University of Lausanne, Biophore, CH-1015 Lausanne, Switzerland.
J Therm Biol. 2014 Apr;41:95-103. doi: 10.1016/j.jtherbio.2014.01.006. Epub 2014 Feb 26.
The thermal energetics of rodents from cool, wet tropical highlands are poorly known. Metabolic rate, body temperature and thermal conductance were measured in the moss-forest rat, Rattus niobe (Rodentia), a small murid endemic to the highlands of New Guinea. These data were evaluated in the context of the variation observed in the genus Rattus and among tropical murids. In 7 adult R. niobe, basal metabolic rate (BMR) averaged 53.6±6.6mLO2h(-1), or 103% of the value predicted for a body mass of 42.3±5.8g. Compared to other species of Rattus, R. niobe combines a low body temperature (35.5±0.6°C) and a moderately low minimal wet thermal conductance cmin (5.88±0.7mLO2h(-1)°C(-1), 95% of predicted) with a small size, all of which lead to reduced energy expenditure in a constantly cool environment. The correlations of mean annual rainfall and temperature, altitude and body mass with BMR, body temperature and cmin were analyzed comparatively among tropical Muridae. Neither BMR, nor cmin or body temperature correlated with ambient temperature or altitude. Some of the factors which promote high BMR in higher latitude habitats, such as seasonal exposure to very low temperature and short reproductive season, are lacking in wet montane tropical forests. BMR increased with rainfall, confirming a pattern observed among other assemblages of mammals. This correlation was due to the low BMR of several desert adapted murids, while R. niobe and other species from wet habitats had a moderate BMR.
来自凉爽、湿润的热带高地的啮齿动物的热能量学鲜为人知。我们对新几内亚高地特有的小型鼠科动物苔藓林鼠（Rattus niobe，啮齿目）的代谢率、体温和热导率进行了测量。这些数据在大鼠属以及热带鼠科动物所观察到的变异背景下进行了评估。在7只成年苔藓林鼠中，基础代谢率（BMR）平均为53.6±6.6毫升氧气/小时，即体重为42.3±5.8克时预测值的103%。与其他大鼠物种相比，苔藓林鼠体型较小，同时具有较低的体温（35.5±0.6°C）和适度较低的最小湿热导率cmin（5.88±0.7毫升氧气/小时·°C-1，为预测值的95%），所有这些因素导致其在持续凉爽的环境中能量消耗减少。我们比较分析了热带鼠科动物中年平均降雨量、温度、海拔和体重与基础代谢率、体温和cmin之间的相关性。基础代谢率、cmin或体温均与环境温度或海拔无关。在湿润的山地热带森林中，缺乏一些在高纬度栖息地促进高基础代谢率的因素，比如季节性暴露于极低温度和较短的繁殖季节。基础代谢率随降雨量增加，这证实了在其他哺乳动物群体中观察到的一种模式。这种相关性是由于几种适应沙漠环境的鼠科动物基础代谢率较低，而苔藓林鼠和其他来自湿润栖息地的物种基础代谢率适中。
