Body mass is associated with hibernation length, body temperature, and heart rate in free-ranging brown bears.

IF 2.6 2区 生物学 Q1 ZOOLOGY
Alina L Evans, Boris Fuchs, Navinder J Singh, Alexandra Thiel, Sylvain Giroud, Stephane Blanc, Timothy G Laske, Ole Frobert, Andrea Friebe, Jon E Swenson, Jon M Arnemo
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引用次数: 1

Abstract

Background: Despite centuries of research, debate remains on the scaling of metabolic rate to mass especially for intraspecific cases. The high variation of body mass within brown bears presents a unique opportunity to study the intraspecific effects of body mass on physiological variables. The amplitude of metabolic rate reduction in hibernators is dependent on body mass of the species. Small hibernators have high metabolic rates when euthermic but experience a drastic decrease in body temperature during torpor, which is necessary to reach a very low metabolic rate. Conversely, large hibernators, such as the brown bear (Ursus arctos), show a moderate decrease in temperature during hibernation, thought to be related to the bear's large size. We studied body mass, abdominal body temperature, heart rate, and accelerometer-derived activity from 63 free-ranging brown bears (1-15 years old, 15-233 kg). We tested for relationships between body mass and body temperature, heart rate, and hibernation duration.

Results: The smallest individuals maintained lower body temperatures during hibernation, hibernated longer, and ended hibernation later than large bears. Unlike body temperature, winter heart rates were not associated with body mass. In summer, the opposite pattern was found, with smaller individuals having higher body temperature and daytime heart rates. Body mass was associated with body temperature in the winter hypometabolic state, even in a large hibernating mammal. Smaller bears, which are known to have higher thermal conductance, reached lower body temperatures during hibernation. During summer, smaller bears had higher body temperatures and daytime heart rates, a phenomenon not previously documented within a single mammalian species.

Conclusion: We conclude that the smallest bears hibernated more deeply and longer than large bears, likely from a combined effect of basic thermodynamics, the higher need for energy savings, and a lower cost of warming up a smaller body.

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在自由放养的棕熊中,体重与冬眠时间、体温和心率有关。
背景:尽管进行了几个世纪的研究,但关于代谢率与质量的比例,特别是种内病例,仍存在争议。棕熊身体质量的高度变化为研究身体质量对生理变量的种内影响提供了一个独特的机会。冬眠动物代谢率下降的幅度取决于该物种的体重。小型冬眠动物在恒温时代谢率高,但在冬眠期间体温急剧下降,这是达到非常低的代谢率所必需的。相反,大型冬眠动物,如棕熊(Ursus arctos),在冬眠期间表现出适度的体温下降,这被认为与熊的大体型有关。我们研究了63只自由放养的棕熊(1-15岁,15-233公斤)的体重、腹部体温、心率和加速度计得出的活动。我们测试了体重与体温、心率和冬眠时间之间的关系。结果:小个体冬眠时体温较低,冬眠时间较长,冬眠结束时间较晚。与体温不同,冬季心率与体重无关。而在夏季,情况正好相反,体型较小的人体温和白天心率更高。在冬季低代谢状态下,体重与体温有关,即使在大型冬眠哺乳动物中也是如此。体型较小的熊被认为具有更高的导热性,在冬眠期间体温较低。在夏天,体型较小的熊有更高的体温和白天的心率,这种现象以前没有在单一哺乳动物物种中记录过。结论:我们得出的结论是,最小的熊比大熊冬眠得更深,冬眠的时间更长,这可能是基本热力学、更高的节能需求和更小的身体取暖成本的综合影响。
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来源期刊
CiteScore
4.90
自引率
0.00%
发文量
29
审稿时长
>12 weeks
期刊介绍: Frontiers in Zoology is an open access, peer-reviewed online journal publishing high quality research articles and reviews on all aspects of animal life. As a biological discipline, zoology has one of the longest histories. Today it occasionally appears as though, due to the rapid expansion of life sciences, zoology has been replaced by more or less independent sub-disciplines amongst which exchange is often sparse. However, the recent advance of molecular methodology into "classical" fields of biology, and the development of theories that can explain phenomena on different levels of organisation, has led to a re-integration of zoological disciplines promoting a broader than usual approach to zoological questions. Zoology has re-emerged as an integrative discipline encompassing the most diverse aspects of animal life, from the level of the gene to the level of the ecosystem. Frontiers in Zoology is the first open access journal focusing on zoology as a whole. It aims to represent and re-unite the various disciplines that look at animal life from different perspectives and at providing the basis for a comprehensive understanding of zoological phenomena on all levels of analysis. Frontiers in Zoology provides a unique opportunity to publish high quality research and reviews on zoological issues that will be internationally accessible to any reader at no cost. The journal was initiated and is supported by the Deutsche Zoologische Gesellschaft, one of the largest national zoological societies with more than a century-long tradition in promoting high-level zoological research.
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