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Survivable hypothermia or torpor in a wild-living rat: rare insights broaden our understanding of endothermic physiology

Nowack, J and Turbill, C (2021) Survivable hypothermia or torpor in a wild-living rat: rare insights broaden our understanding of endothermic physiology. Journal of Comparative Physiology B. ISSN 0174-1578

Nowack and Turbill 2021. Survivable Hypothermia Or Torpor In Bush Rats.pdf - Published Version
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Maintaining a high and stable body temperature as observed in endothermic mammals and birds is energetically costly. Thus, it is not surprising that we discover more and more heterothermic species that can reduce their energetic needs during energetic bottlenecks through the use of torpor. However, not all heterothermic animals use torpor on a regular basis. Torpor may also be important to an individual’s probability of survival, and hence fitness, when used infrequently. We here report the observation of a single, ~ 5.5 h long hypothermic bout with a decrease in body temperature by 12 °C in the native Australian bush rat (Rattus fuscipes). Our data suggest that bush rats are able to rewarm from a body temperature of 24 °C, albeit with a rewarming rate lower than that expected on the basis of their body mass. Heterothermy, i.e. the ability to withstand and overcome periods of reduced body temperature, is assumed to be an evolutionarily ancestral (plesiomorphic) trait. We thus argue that such rare hypothermic events in species that otherwise appear to be strictly homeothermic could be heterothermic rudiments, i.e. a less derived form of torpor with limited capacity for rewarming. Importantly, observations of rare and extreme thermoregulatory responses by wild animals are more likely to be discovered with long-term data sets and may not only provide valuable insight about the physiological capability of a population, but can also help us to understand the constraints and evolutionary pathways of different phenologies.

Item Type: Article
Uncontrolled Keywords: 0601 Biochemistry and Cell Biology, 0606 Physiology, 0608 Zoology
Subjects: Q Science > QH Natural history
Q Science > QH Natural history > QH301 Biology
Q Science > QL Zoology
Q Science > QR Microbiology
Divisions: Biological & Environmental Sciences (from Sep 19)
Publisher: Springer
Date Deposited: 20 Oct 2021 10:27
Last Modified: 20 Oct 2021 10:30
DOI or ID number: 10.1007/s00360-021-01416-3
URI: https://researchonline.ljmu.ac.uk/id/eprint/15671
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