Department of Animal Ecology and Conservation, Biocentre Grindel, University of Hamburg, Hamburg, Germany.
PLoS One. 2010 May 24;5(5):e10797. doi: 10.1371/journal.pone.0010797.
Hibernation and daily torpor are energy- and water-saving adaptations employed to survive unfavourable periods mostly in temperate and arctic environments, but also in tropical and arid climates. Heterothermy has been found in a number of mammalian orders, but within the primates so far it seems to be restricted to one family of Malagasy lemurs. As currently there is no evidence of heterothermy of a primate outside of Madagascar, the aim of our study was to investigate whether small primates from mainland Africa are indeed always homeothermic despite pronounced seasonal changes in weather and food availability.
METHODOLOGY/PRINCIPAL FINDINGS: One of the nearest relatives of Malagasy lemurs, the African lesser bushbaby, Galago moholi, which inhabits a highly seasonal habitat with a hot wet-season and a cold dry-season with lower food abundance, was investigated to determine whether it is capable of heterothermy. We measured skin temperature of free-ranging individuals throughout the cool dry season using temperature-sensitive collars as well as metabolic rate in captured individuals. Torpor was employed by 15% of 20 animals. Only one of these animals displayed heterothermy in response to natural availability of food and water, whereas the other animals became torpid without access to food and water.
CONCLUSIONS/SIGNIFICANCE: Our results show that G. moholi are physiologically capable of employing torpor. However they do not use it as a routine behaviour, but only under adverse conditions. This reluctance is presumably a result of conflicting selective pressures for energy savings versus other ecological and evolutionary forces, such as reproduction or territory defence. Our results support the view that heterothermy in primates evolved before the division of African and Malagasy Strepsirhini, with the possible implication that more primate species than previously thought might still have the potential to call upon this possibility, if the situation necessitates it.
冬眠和日常蛰伏是动物为了在不利时期生存而采取的节能和节水适应策略，这些时期主要发生在温带和北极环境中，但也存在于热带和干旱气候中。异温动物在许多哺乳动物目中都有发现，但在灵长类动物中，目前似乎只限于马达加斯加狐猴的一个科。由于目前没有证据表明除了马达加斯加以外的灵长类动物存在异温现象，因此我们的研究目的是调查非洲大陆的小型灵长类动物是否确实始终是恒温动物，尽管天气和食物供应有明显的季节性变化。
方法/主要发现：马达加斯加狐猴的最近亲属之一，非洲小懒猴 Galago moholi，生活在一个季节性很强的栖息地，有炎热的雨季和寒冷的旱季，食物丰富度较低，我们调查了它是否有能力进行异温现象。我们使用温度敏感项圈测量了自由生活个体在整个凉爽旱季的皮肤温度，以及在捕获个体中的代谢率。20 只动物中有 15%进入了蛰伏状态。这些动物中只有一只对食物和水的自然供应做出了异温反应，而其他动物在没有食物和水的情况下进入了蛰伏状态。
结论/意义：我们的结果表明，G. moholi 在生理上有能力采用蛰伏。然而，它们并没有将其作为常规行为，而是仅在不利条件下使用。这种不情愿可能是由于能量节约与其他生态和进化力量（如繁殖或领地防御）之间存在冲突的选择压力所致。我们的结果支持这样一种观点，即灵长类动物的异温现象是在非洲和马达加斯加的原始灵长类动物分化之前进化而来的，这可能意味着比以前认为的更多的灵长类物种仍然有可能在必要时利用这种可能性。
