Körtner Gerhard, Pavey Chris R, Geiser Fritz
Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia.
Physiol Biochem Zool. 2008 Jul-Aug;81(4):442-51. doi: 10.1086/589545.
Little is known about the energy conservation strategies of free-ranging marsupials living in resource-poor Australian deserts. We studied activity patterns and torpor of free-living mulgaras (Dasycercus blythi) in arid central Australia during the winter of 2006. Mulgaras are small (approximately 75 g), nocturnal, insectivorous marsupials, with a patchy distribution in hummock grasslands. Mulgaras (six males, three females) were implanted intraperitoneally with temperature-sensitive transmitters and monitored for 6-55 d. Temperature profiles for different microhabitats and the thermal properties of soil and a number of burrows were also measured. Air temperature ranged from -3 degrees C at night to 30 degrees C during the day. Although burrows buffered temperature extremes, the thermal diffusivity of the sandy soil was high, and many burrows were shallow. Hence, soil and burrow temperatures averaged about 15 degrees C. The activity of mulgaras was often restricted to a few hours after sunset, before they retired into their burrows. Mulgaras employed torpor frequently, often entering torpor during the night and arousing around midday, with arousals occurring later on cooler days. Shallow burrows allowed cooling below mean T(soil). Consequently, body temperatures as low as 10.8 degrees C were observed. The longest torpor bout was 20.8 h. Torpor patterns changed seasonally and differed between males and females. From June to August, females entered torpor almost daily despite mating and gestation, but from the end of the gestation period onward, they remained normothermic. In contrast, males showed only shallow and short torpor during the mating season, but from mid-July, a transition to more frequent and deeper torpor resembling that of females was observed. Apparently, in both sexes, the reproductive effort entails energetic costs, but torpor, as an energy-saving mechanism, and reproduction are not exclusive in mulgaras. In a resource-poor environment during the least productive part of the year, frequent torpor seems to provide the means to compensate for the increased energetic costs associated with reproduction.
对于生活在资源匮乏的澳大利亚沙漠中的野生有袋动物的能量守恒策略，人们了解甚少。我们在2006年冬季对澳大利亚中部干旱地区自由生活的毛鼻袋熊（Dasycercus blythi）的活动模式和蛰伏状态进行了研究。毛鼻袋熊体型较小（约75克），夜行性，以昆虫为食，在小丘草原上分布零散。给7只毛鼻袋熊（6只雄性，3只雌性）腹腔植入温度敏感发射器，并监测6 - 55天。还测量了不同微生境的温度曲线以及土壤和一些洞穴的热特性。气温范围从夜间的 - 3摄氏度到白天的30摄氏度。虽然洞穴缓冲了极端温度，但沙质土壤的热扩散率很高，而且许多洞穴很浅。因此，土壤和洞穴温度平均约为15摄氏度。毛鼻袋熊的活动通常仅限于日落后的几个小时，之后它们就回到洞穴中。毛鼻袋熊频繁进入蛰伏状态，通常在夜间进入蛰伏，中午左右苏醒，在较凉爽的日子里苏醒时间会更晚。浅洞穴使得体温能降至土壤平均温度以下。因此，观察到体温低至10.8摄氏度。最长的蛰伏期为20.8小时。蛰伏模式随季节变化，且雄性和雌性有所不同。从6月到8月，雌性几乎每天都进入蛰伏状态，尽管处于交配和妊娠期，但从妊娠期结束后，它们保持正常体温。相比之下，雄性在交配季节仅表现出浅而短的蛰伏，但从7月中旬开始，观察到它们向更频繁、更深的蛰伏转变，类似于雌性的蛰伏模式。显然，对于两性来说，繁殖活动都需要消耗能量，但蛰伏作为一种节能机制，与繁殖在毛鼻袋熊身上并非相互排斥。在一年中生产力最低的时期、资源匮乏的环境中，频繁的蛰伏似乎为补偿与繁殖相关的能量消耗增加提供了一种方式。
