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Przybylska-Piech AS, Nowak A, Jefimow M. Warm spells in winter affect the equilibrium between winter phenotypes. J Therm Biol 2024; 120:103811. [PMID: 38382412 DOI: 10.1016/j.jtherbio.2024.103811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 01/10/2024] [Accepted: 01/26/2024] [Indexed: 02/23/2024]
Abstract
Each phenotype is a product of the interaction of the genes and the environment. Although winter phenotype in seasonal mammals is heritable, its development may be modified by external conditions. In today's world, global climate change and increasing frequency of unpredictable weather events may affect the dynamic equilibrium between phenotypes. We tested the effect of changes in ambient temperature during acclimation to short photoperiod on the development of winter phenotypes in three generations of Siberian hamsters (Phodopus sungorus). Based on seasonal changes in fur colour, body mass, and expression of daily torpor we distinguished three different winter phenotypes: responding, non-responding, and partially-responding to short photoperiod. We found that warm spells in winter can increase the proportion of non-responding individuals in the population, while stable winter conditions can increase photoresponsiveness among the offspring of non-responders. We conclude that the polymorphism of winter phenotype is an inherent characteristic of the Siberian hamster population but the development of winter phenotype is not fixed but rather a plastic response to the environmental conditions.
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Affiliation(s)
| | - Anna Nowak
- Department of Vertebrate Zoology and Ecology, Nicolaus Copernicus University, Toruń, Poland
| | - Małgorzata Jefimow
- Department of Animal Physiology and Neurobiology, Nicolaus Copernicus University Toruń, Poland.
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2
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Nespolo RF, Peña I, Mejías C, Ñunque A, Altamirano T, Bozinovic FF. Communal nesting is the optimal strategy for heat conservation in a social marsupial: lessons from biophysical models. J Exp Biol 2022; 225:284634. [PMID: 36420835 PMCID: PMC9720746 DOI: 10.1242/jeb.244606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 11/07/2022] [Indexed: 11/25/2022]
Abstract
Endothermy, understood as the maintenance of continuous and high body temperatures owing to the combination of metabolic heat production and an insulative cover, is severely challenged in small endotherms inhabiting cold environments. As a response, social clustering combined with nest use (=communal nesting) is a common strategy for heat conservation. To quantify the actual amount of energy that is saved by this strategy, we studied the social marsupial Dromiciops gliroides (monito del monte), an endemic species of the cold forests of southern South America. It is hypothesized that sociability in this marsupial was driven by cold conditions, but evidence supporting this hypothesis is unclear. Here, we used taxidermic models ('mannequins') to experimentally test the energetic benefits of clustering combined with nest use. To do this, we fitted and compared cooling curves of solitary and grouped mannequins, within and outside of a nest, at the typical winter ambient temperatures of their habitat (5°C). We found that the strategy that minimized euthermic cost of maintenance was the combination of nest use and clustering, thus supporting communal nesting as a social adaptation to cope with the cold. Considering the basal metabolic rate of monitos, our estimates suggest that the savings represents almost half of energy consumption per day (in resting conditions). This study shows how simple biophysical models could help to evaluate bioenergetic hypotheses for social behavior in cold-adapted endotherms.
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Affiliation(s)
- Roberto F. Nespolo
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile,Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile,Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Santiago, Chile,Millennium Nucleus of Patagonian Limit of Life (LiLi), Valdivia, Chile,Author for correspondence ()
| | - Isabella Peña
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
| | - Carlos Mejías
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile,Magister en Ecología Aplicada, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Abel Ñunque
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile,Millennium Nucleus of Patagonian Limit of Life (LiLi), Valdivia, Chile
| | - Tomás Altamirano
- ECOS (Ecology-Complexity-Society) Laboratory, Center for Local Development (CEDEL), Pontificia Universidad Católica de Chile, Villarrica Campus, La Araucanía Region, Chile,National Audubon Society and Cape Horn International Center for Global Change Studies and Biocultural Conservation, Universidad de Magallanes, Punta Arenas, Chile,Millennium Nucleus Center for the Socioeconomic Impact of Environmental Policies (CESIEP), Chile
| | - Francisco F. Bozinovic
- Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Santiago, Chile,Departamento de Ecología Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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3
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Charlanne LM, Vetter S, Einwaller J, Painer J, Gilbert C, Giroud S. Sticking Together: Energetic Consequences of Huddling Behavior in Hibernating Juvenile Garden Dormice. Physiol Biochem Zool 2022; 95:400-415. [PMID: 35930826 DOI: 10.1086/721184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
AbstractHibernation, or multiday torpor, allows individuals to save energy via substantial reductions of metabolism and body temperature but is regularly interrupted by euthermic phases called arousals. Social thermoregulation, or "huddling," can act in synergy with torpor in reducing individuals' energy and heat losses. In the wild, the garden dormouse (Eliomys quercinus) combines both strategies, which are crucial for winter survival of juveniles with limited prehibernation body fat reserves. We investigated via thermographic and temperature measurements (i) the energetic impact of huddling during an arousal from deep torpor, (ii) the dynamics of huddling behavior during hibernation, and (iii) its consequences during the entire winter in juvenile garden dormice. Thermographic images revealed a significant effect of huddling on torpor energetics, as it reduced heat exchange and mass loss by two-thirds in huddling versus single individuals during arousal. Our investigation of the dynamics of huddling further revealed a "random-like mechanistic" behavior during winter hibernation, as arousals from torpor were not always initiated by the same individuals. Animals took turns in initiating rewarming within a group, and the individual with highest body temperature during arousal entered into torpor later than the others within the huddle. The animals share both costs and benefits of huddling during arousals, without any energetic benefit of huddling over the entire winter on an individual level. We conclude that the dynamics of social thermoregulation during hibernation seems to counterbalance its benefit of reducing energetic costs associated against the energy-demanding process of rewarming from torpor.
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4
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Housing conditions modify seasonal changes in basal metabolism and body mass of the Siberian hamster, Phodopus sungorus. J Comp Physiol B 2022; 192:513-526. [PMID: 35348882 PMCID: PMC9197917 DOI: 10.1007/s00360-022-01434-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 02/21/2022] [Accepted: 03/07/2022] [Indexed: 10/27/2022]
Abstract
Proper housing conditions are important aspects of animal welfare. Animals housed in enriched environments show less stereotypic behaviours than animals kept in barren cages. However, different types of cage enrichment may affect the results of experimental studies and hinder comparative analyses of animal physiology and behaviour. We investigated whether access to a running wheel, availability of nesting material, and pair housing affect basal metabolic rate (BMR) of Siberian hamsters (Phodopus sungorus) under various acclimation conditions. We used 70 adult hamsters (35 males and 35 females) divided into five groups housed under different cage conditions. All individuals experienced the same acclimation procedure: first a winter (L8:D16) then a summer (L16:D8) photoperiod, at air temperatures of first 20 °C then 7 °C under both photoperiods. We found that nesting material and pair housing did not affect hamster BMR, while access to a running wheel increased BMR and body mass regardless of photoperiod and ambient temperature. Thus, we suggest that cage enrichment should be applied with caution, especially in studies on energetics or thermoregulation, particularly in seasonal animals.
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Social thermoregulation in Mediterranean greater white-toothed shrews (Crocidura russula). Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03072-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Xu JH, Wang Z, Mou JJ, Wang CL, Huang WM, Xue HL, Wu M, Chen L, Xu LX. Up-Regulation of Glycogen Synthesis and Degradation Enzyme Level Maintained Myocardial Glycogen in Huddling Brandt's Voles Under Cool Environments. Front Physiol 2021; 12:593129. [PMID: 33841168 PMCID: PMC8033036 DOI: 10.3389/fphys.2021.593129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 03/04/2021] [Indexed: 11/13/2022] Open
Abstract
Small mammals exhibit limited glucose use and glycogen accumulation during hypothermia. Huddling is a highly evolved cooperative behavioral strategy in social mammals, allowing adaptation to environmental cooling. However, it is not clear whether this behavior affects the utilization of glycogen in cold environments. Here, we studied the effects of huddling on myocardial glycogen content in Brandt’s voles (Lasiopodomys brandtii) under a mild cold environment (15°C). Results showed that (1) Compared to the control (22°C) group (CON), the number of glycogenosomes more than tripled in the cool separated group (CS) in both males and females; whereas the number of glycogenosomes increased in females but was maintained in males in the cool huddling group (CH). (2) Glycogen synthase (GS) activity in the CS group remained unchanged, whereas glycogen phosphorylase (GYPL) activity decreased, which mediated the accumulation of glycogen content of the CS group. (3) Both GS and GYPL activity increased which may contribute to the stability of glycogen content in CH group. (4) The expression levels of glucose transporters GLUT1 and GLUT4 increased in the CS group, accompanied by an increase in glucose metabolism. These results indicate that the reduced glycogen degradation enzyme level and enhanced glucose transport may lead to an increase in myocardial glycogen content of the separated voles under cool environment; while the up-regulation of glycogen synthesis and degradation enzyme level maintained myocardial glycogen content in the huddling vole.
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Affiliation(s)
- Jin-Hui Xu
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Zhe Wang
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Jun-Jie Mou
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Chuan-Li Wang
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Wei-Mei Huang
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Hui-Liang Xue
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Ming Wu
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Lei Chen
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Lai-Xiang Xu
- College of Life Sciences, Qufu Normal University, Qufu, China
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7
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Swanson DL, Agin TJ, Zhang Y, Oboikovitz P, DuBay S. Metabolic Flexibility in Response to Within-Season Temperature Variability in House Sparrows. Integr Org Biol 2021; 2:obaa039. [PMID: 33791577 PMCID: PMC7810579 DOI: 10.1093/iob/obaa039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The climatic variability hypothesis (CVH) posits that more flexible phenotypes should provide a fitness advantage for organisms experiencing more variable climates. While typically applied across geographically separated populations, whether this principle applies across seasons or other conditions (e.g., open vs. sheltered habitats) which differ in climatic variability remains essentially unstudied. In north-temperate climates, climatic variability in winter usually exceeds that in summer, so extending the CVH to within-population seasonal variation predicts that winter phenotypes should be more flexible than summer phenotypes. We tested this prediction of the within-season extension of the CVH by acclimating summer and winter-collected house sparrows (Passer domesticus) to 24, 5, and -10°C and measuring basal metabolic rate (BMR) and summit metabolic rate (Msum = maximum cold-induced metabolic rate) before and after acclimation (Accl). To examine mechanistic bases for metabolic variation, we measured flight muscle and heart masses and citrate synthase and β-hydroxyacyl coA-dehydrogenase activities. BMR and Msum were higher for cold-acclimated than for warm-acclimated birds, and BMR was higher in winter than in summer birds. Contrary to our hypothesis of greater responses to cold Accl in winter birds, metabolic rates generally decreased over the Accl period for winter birds at all temperatures but increased at cold temperatures for summer birds. Flight muscle and heart masses were not significantly correlated with season or Accl treatment, except for supracoracoideus mass, which was lower at -10°C in winter, but flight muscle and heart masses were positively correlated with BMR and flight muscle mass was positively correlated with Msum. Catabolic enzyme activities were not clearly related to metabolic variation. Thus, our data suggest that predictions of the CVH may not be relevant when extended to seasonal temperature variability at the within-population scale. Indeed, these data suggest that metabolic rates are more prominently upregulated in summer than in winter in response to cold. Metabolic rates tended to decrease during Accl at all temperatures in winter, suggesting that initial metabolic rates at capture (higher in winter) influence metabolic Accl for captive birds.
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Affiliation(s)
- D L Swanson
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
| | - T J Agin
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
| | - Y Zhang
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
| | - P Oboikovitz
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
| | - S DuBay
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
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8
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Mortola JP. Social interaction and the thermogenic response of chicken hatchlings. Physiol Behav 2021; 232:113317. [PMID: 33472054 DOI: 10.1016/j.physbeh.2021.113317] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 01/11/2021] [Accepted: 01/15/2021] [Indexed: 11/19/2022]
Abstract
The aggregation of two or more individuals of the same species (huddling) is common in mammals and birds, especially in the cold. The physical contact reduces the weight-specific body surface exposed to the environment, thus lowering heat loss and the thermogenic needs. This study investigated the possibility that the mere presence of a conspecific, in absence of physical contact, may by itself influence metabolic rate during cold. The oxygen consumption (Vo2) of pairs of chicken hatchlings was measured when the hatchlings were in isolation (individuals), together in the respirometer but kept separated by a grid (separated) or together in the respirometer free to huddle (together), in random order, in warm (ambient normothermia, 37.5 °C) and cold conditions (26 °C, 1 h). In warm, Vo2 did not differ significantly among individuals, separated and together (~ 1.03 ± 0.04 ml O2/min). During the whole cold period, Vo2 of individuals exceeded the value by 23.3 ± 3.1 ml of O2, significantly more than in separated (15.3 ± 2.0 ml O2, P<0.01) and together (13.9 ± 3.3 ml O2; P<0.001). Separated and together did not differ significantly. Vo2 in the cold averaged 149 ± 7% of the value measured in normothermia in isolated, 132 ± 5% in separated and 128 ± 7% in together. By the end of the cold-exposure, Vo2 averaged 166 ± 8% of normothermia in isolated, 146 ± 8% in separated and 140 ± 9% in together. In all cases, values of isolated significantly exceeded those of separated (P<0.01) and together (P<0.0001), while separated and together did not differ from each other (P>0.05; Two-way RM ANOVA). Hence, in this experimental model, social interaction without physical contact decreased the thermogenic response to cold as much as huddling did. Presumably, during the cold exposure, social interaction lowered the additional energetic cost of the stress of isolation.
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Affiliation(s)
- Jacopo P Mortola
- Department of Physiology, McGill University, 3655 Sir William Osler promenade, Montreal, QC, Canada, H3G 1Y6.
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9
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Wang Z, Xu JH, Mou JJ, Kong XT, Zou JW, Xue HL, Wu M, Xu LX. Novel ultrastructural findings on cardiac mitochondria of huddling Brandt's voles in mild cold environment. Comp Biochem Physiol A Mol Integr Physiol 2020; 249:110766. [DOI: 10.1016/j.cbpa.2020.110766] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/25/2020] [Accepted: 07/09/2020] [Indexed: 10/23/2022]
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10
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Ruf T, Bieber C. Physiological, Behavioral, and Life-History Adaptations to Environmental Fluctuations in the Edible Dormouse. Front Physiol 2020; 11:423. [PMID: 32431626 PMCID: PMC7214925 DOI: 10.3389/fphys.2020.00423] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/07/2020] [Indexed: 11/22/2022] Open
Abstract
The edible dormouse (Glis glis, formerly Myoxus glis) is a small arboreal mammal inhabiting deciduous forests in Europe. This rodent shows behavioral and physiological adaptations to three types of environmental fluctuations: (i) predictable seasonal variation in climate and food resources (ii) unpredictable year-to-year fluctuation in seed-production by trees and (iii) day-to-day variation in ambient temperature and precipitation. They cope with seasonally fluctuating conditions by seasonal fattening and hibernation. Dormice have adjusted to tree-mast fluctuations, i.e., pulsed resources, by sensing future seed availability in spring, and restricting reproduction to years with at least some seed production by beech and oak trees, which are a crucial food-resource for fast-growing juveniles in fall. Finally, dormice respond to short-term drops in ambient temperature by increased use of daily torpor as well as by huddling in groups of up to 24 conspecifics. These responses to environmental fluctuations strongly interact with each other: Dormice are much more prone to using daily torpor and huddling in non-reproductive years, because active gonads can counteract torpor and energy requirements for reproduction may prevent the sharing of food resources associated with huddling. Accordingly, foraging activity in fall is much more intense in reproductive mast years. Also, depending on their energy reserves, dormice may retreat to underground burrows in the summers of non-reproductive years, causing an extension of the hibernation season to up to 11.4 months. In addition to these interactions, responses to environmental fluctuations are modulated by the progression of life-history stages. With increasing age and diminishing chances of future reproduction, females reproduce with increasing frequency even under suboptimal environmental conditions. Simultaneously, older dormice shorten the hibernation season and phase-advance the emergence from hibernation in spring, apparently to occupy good breeding territories early, despite increased predation risk above ground. All of the above adaptions, i.e., huddling, torpor, hibernation, and reproduction skipping do not merely optimize energy-budgets but also help to balance individual predation risk against reproductive success, which adds another layer of complexity to the ability to make flexible adjustments in this species.
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Affiliation(s)
- Thomas Ruf
- Research Institute of Wildlife Ecology, Department of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Claudia Bieber
- Research Institute of Wildlife Ecology, Department of Interdisciplinary Life Sciences, University of Veterinary Medicine, Vienna, Austria
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11
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Eto T, Sakamoto SH, Okubo Y, Tsuzuki Y, Koshimoto C, Morita T. Individual variation of daily torpor and body mass change during winter in the large Japanese field mouse (Apodemus speciosus). J Comp Physiol B 2018; 188:1005-1014. [PMID: 30194463 DOI: 10.1007/s00360-018-1179-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 08/12/2018] [Accepted: 09/03/2018] [Indexed: 11/24/2022]
Abstract
Daily torpor is a strategy used by some overwintering small endotherms to aid in energy conservation. However, the pattern of torpor varies among individuals within species and populations, even under the same environmental conditions, with significant implications for survival rate and reproductive success. Body mass is one factor that may influence this variation, especially in some small mammals that accumulate fat stores prior to overwintering. However, to our knowledge there has been no previous study examining the detailed relationships between torpor expression and body mass change in small mammals that hoard food as an energy resource during winter. The large Japanese field mouse, Apodemus speciosus, whose winter survival strategy depends on food caches instead of fat stores, displays daily torpor under artificial winter conditions (short-day photoperiod and cold). The present study clarifies the characteristics and patterns of daily torpor and body mass change in this species in the laboratory. Although expression of daily torpor was facilitated progressively as in other species, the observed patterns of torpor expression and body mass change showed considerable individual variation. Moreover, there was no obvious correlation between body mass and daily torpor expression. Therefore, it is suggested that in A. speciosus body mass may not contribute to individual variation of daily torpor during winter. Daily torpor during winter may be adjusted by not only mechanisms common to other small mammals, but also species-specific factors relating to the external or internal reserves of energy in small mammals.
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Affiliation(s)
- Takeshi Eto
- Interdisciplinary Graduate School of Agriculture and Engineering, Kibana Campus, University of Miyazaki, Miyazaki, 889-2192, Japan.,Center for Toki and Ecological Restoration, Niigata University, Niigata, 952-0103, Japan
| | - Shinsuke H Sakamoto
- Faculty of Agriculture, Kibana Campus, University of Miyazaki, Miyazaki, 889-2192, Japan
| | - Yoshinobu Okubo
- Interdisciplinary Graduate School of Agriculture and Engineering, Kibana Campus, University of Miyazaki, Miyazaki, 889-2192, Japan
| | - Yasuhiro Tsuzuki
- Faculty of Agriculture, Kibana Campus, University of Miyazaki, Miyazaki, 889-2192, Japan
| | - Chihiro Koshimoto
- Division of Bio-Resources, Frontier Science Research Center, Kiyotake Campus, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Tetsuo Morita
- Faculty of Agriculture, Kibana Campus, University of Miyazaki, Miyazaki, 889-2192, Japan. .,Division of Bio-Resources, Frontier Science Research Center, Kiyotake Campus, University of Miyazaki, Miyazaki, 889-1692, Japan.
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12
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Olson MN, Bowman J, Burness G. Social thermoregulation does not explain heterospecific nesting in North American flying squirrels. Biol J Linn Soc Lond 2018. [DOI: 10.1093/biolinnean/bly014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Megan N Olson
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada
| | - Jeff Bowman
- Wildlife Research and Monitoring Section, Ontario Ministry of Natural Resources and Forestry, Trent University DNA Building, Peterborough, ON, Canada
| | - Gary Burness
- Department of Biology, Trent University, Peterborough, ON, Canada
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13
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Seasonal energetics and torpor use in North American flying squirrels. J Therm Biol 2017; 70:46-53. [DOI: 10.1016/j.jtherbio.2017.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 10/04/2017] [Accepted: 10/21/2017] [Indexed: 11/18/2022]
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14
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Geiser F, Gasch K, Bieber C, Stalder GL, Gerritsmann H, Ruf T. Basking hamsters reduce resting metabolism, body temperature and energy costs during rewarming from torpor. ACTA ACUST UNITED AC 2016; 219:2166-72. [PMID: 27207637 DOI: 10.1242/jeb.137828] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/02/2016] [Indexed: 01/22/2023]
Abstract
Basking can substantially reduce thermoregulatory energy expenditure of mammals. We tested the hypothesis that the largely white winter fur of hamsters (Phodopus sungorus), originating from Asian steppes, may be related to camouflage to permit sun basking on or near snow. Winter-acclimated hamsters in our study were largely white and had a high proclivity to bask when resting and torpid. Resting hamsters reduced metabolic rate (MR) significantly (>30%) when basking at ambient temperatures (Ta) of ∼15 and 0°C. Interestingly, body temperature (Tb) also was significantly reduced from 34.7±0.6°C (Ta 15°C, not basking) to 30.4±2.0°C (Ta 0°C, basking), which resulted in an extremely low (<50% of predicted) apparent thermal conductance. Induced torpor (food withheld) during respirometry at Ta 15°C occurred on 83.3±36.0% of days and the minimum torpor MR was 36% of basal MR at an average Tb of 22.0±2.6°C; movement to the basking lamp occurred at Tb<20.0°C. Energy expenditure for rewarming was significantly reduced (by >50%) during radiant heat-assisted rewarming; however, radiant heat per se without an endogenous contribution by animals did not strongly affect metabolism and Tb during torpor. Our data show that basking substantially modifies thermal energetics in hamsters, with a drop of resting Tb and MR not previously observed and a reduction of rewarming costs. The energy savings afforded by basking in hamsters suggest that this behaviour is of energetic significance not only for mammals living in deserts, where basking is common, but also for P. sungorus and probably other cold-climate mammals.
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Affiliation(s)
- Fritz Geiser
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Kristina Gasch
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Claudia Bieber
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Gabrielle L Stalder
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Hanno Gerritsmann
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
| | - Thomas Ruf
- Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1, Vienna 1160, Austria
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15
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Kuepper ND, Melber M, Kerth G. Nightly clustering in communal roosts and the regular presence of adult females at night provide thermal benefits for juvenile Bechstein's bats. Mamm Biol 2016. [DOI: 10.1016/j.mambio.2015.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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16
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Nowack J, Geiser F. Friends with benefits: the role of huddling in mixed groups of torpid and normothermic animals. ACTA ACUST UNITED AC 2015; 219:590-6. [PMID: 26685170 DOI: 10.1242/jeb.128926] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 12/01/2015] [Indexed: 12/24/2022]
Abstract
Huddling and torpor are widely used for minimizing heat loss by mammals. Despite the questionable energetic benefits from social heterothermy of mixed groups of warm normothermic and cold torpid individuals, the heterothermic Australian sugar glider (Petaurus breviceps) rests in such groups during the cold season. To unravel why they might do so, we examined torpor expression of two sugar glider groups of four individuals each in outside enclosures during winter. We observed 79 torpor bouts during 50 days of observation and found that torpor bouts were longer and deeper when all individuals of a group entered torpor together, and therefore infer that they would have saved more energy in comparison to short and shallow solitary torpor bouts. However, all gliders of either group only expressed torpor uniformly in response to food restriction, whereas on most occasions at least one individual per group remained normothermic. Nevertheless, the presence of warm gliders in mixed groups also appears to be of energetic advantage for torpid individuals, because nest box temperature was negatively correlated with the number of torpid gliders, and normothermic individuals kept the nest temperature at a value closer to the threshold for thermoregulatory heat production during torpor. Our study suggests that mixed groups of torpid and normothermic individuals are observed when environmental conditions are adverse but food is available, leading to intermediate energy savings from torpor. However, under especially challenging conditions and when animals are starving, energy savings are maximized by uniform and pronounced expression of torpor.
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Affiliation(s)
- Julia Nowack
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, New South Wales 2351, Australia
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Boratyński JS, Willis CKR, Jefimow M, Wojciechowski MS. Huddling reduces evaporative water loss in torpid Natterer's bats, Myotis nattereri. Comp Biochem Physiol A Mol Integr Physiol 2014; 179:125-32. [PMID: 25289993 DOI: 10.1016/j.cbpa.2014.09.035] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/18/2014] [Accepted: 09/25/2014] [Indexed: 11/17/2022]
Abstract
Periodic arousals during hibernation consume most of the winter energy budget for hibernating mammals. Evaporative water loss (EWL) is thought to affect the frequency of arousals and thus energy balance, and might have dramatic implications for over-winter survival and fitness. We hypothesized that huddling affects EWL and energy expenditure in torpid mammals. We tested this hypothesis using bats as a model and predicted that, during torpor, EWL and energy expenditure of huddling individuals would be lower than in individuals that are not in a huddle. We measured EWL and metabolic rate of torpid Myotis nattereri (Kuhl, 1817) huddling in groups or roosting individually. Evaporative water loss in huddling individual bats was almost 30% lower than in solitary animals (P=0.03), even after correcting for the effects of metabolic rate. Our results suggest that conservation of water is a substantial benefit underlying huddling by bats during hibernation. Ultimately, huddling could reduce the total cost of hibernation by reducing the number of expensive periodic arousals from torpor caused by the need to supplement water.
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Affiliation(s)
- Jan S Boratyński
- Nicolaus Copernicus University, Department of Animal Physiology, ul. Lwowska 1, 87-100 Toruń, Poland
| | - Craig K R Willis
- Department of Biology and Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, Canada
| | - Małgorzata Jefimow
- Nicolaus Copernicus University, Department of Animal Physiology, ul. Lwowska 1, 87-100 Toruń, Poland
| | - Michał S Wojciechowski
- Nicolaus Copernicus University, Department of Animal Physiology, ul. Lwowska 1, 87-100 Toruń, Poland.
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18
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McCue MD, Voigt CC, Jefimow M, Wojciechowski MS. Thermal acclimation and nutritional history affect the oxidation of different classes of exogenous nutrients in Siberian hamsters, Phodopus sungorus. ACTA ACUST UNITED AC 2014; 321:503-14. [PMID: 25045129 DOI: 10.1002/jez.1882] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 05/05/2014] [Accepted: 06/16/2014] [Indexed: 11/06/2022]
Abstract
During acclimatization to winter, changes in morphology and physiology combined with changes in diet may affect how animals use the nutrients they ingest. To study (a) how thermal acclimation and (b) nutritional history affect the rates at which Siberian hamsters (Phodopus sungorus) oxidize different classes of dietary nutrients, we conducted two trials in which we fed hamsters one of three (13) C-labeled compounds, that is, glucose, leucine, or palmitic acid. We predicted that under acute cold stress (3 hr at 2°C) hamsters previously acclimated to cold temperatures (10°C) for 3 weeks would have higher resting metabolic rate (RMR) and would oxidize a greater proportion of dietary fatty acids than animals acclimated to 21°C. We also investigated how chronic nutritional stress affects how hamsters use dietary nutrients. To examine this, hamsters were fed four different diets (control, low protein, low lipid, and low-glycemic index) for 2 weeks. During cold challenges, hamsters previously acclimated to cold exhibited higher thermal conductance and RMR, and also oxidized more exogenous palmitic acid during the postprandial phase than animals acclimated to 21°C. In the nutritional stress trial, hamsters fed the low protein diet oxidized more exogenous glucose, but not more exogenous palmitic acid than the control group. The use of (13) C-labeled metabolic tracers combined with breath testing demonstrated that both thermal and nutritional history results in significant changes in the extent to which animals oxidize dietary nutrients during the postprandial period.
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Affiliation(s)
- Marshall D McCue
- Department of Biological Sciences, St. Mary's University, San Antonio, Texas
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19
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The effects of poly-unsaturated fatty acids on the physiology of hibernation in a South American marsupial, Dromiciops gliroides. Comp Biochem Physiol A Mol Integr Physiol 2014; 177:62-9. [PMID: 25047800 DOI: 10.1016/j.cbpa.2014.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 06/24/2014] [Accepted: 07/03/2014] [Indexed: 10/25/2022]
Abstract
Many mammals hibernate, which is a profound lethargic state of several weeks or months during winter, that represents a transitory episode of hetherothermy. As with other cases of dormancy, the main benefit of hibernation seems to be energy saving. However, the depth and duration of torpor can be experimentally modified by the composition of food, especially by fattyacid composition. In eutherians, diets rich in unsaturated fatty acids (i.e., fatty acids with at least one double bond) lengthen torpor, reduce metabolism and permit hibernation at lower temperatures. Here we studied whether diets varying in fatty acid composition have an effect on the physiology of hibernation in a South American marsupial, Dromiciops gliroides. We designed a factorial experiment where thermal acclimation (two levels: natural versus constant temperature) was combined with diet acclimation: saturated (i.e., diets with high concentration of saturated fatty acids) versus unsaturated (i.e., diets with high concentration of unsaturated fatty acids). We measured energy metabolism in active and torpid individuals, as well as torpor duration, and a suite of 12 blood biochemical parameters. After a cafeteria test, we found that D. gliroides did not show any preference for a given diet. Also, we did not find effects of diet on body temperature during torpor, or its duration. However, saturated diets, combined with high temperatures provoked a disproportionate increase in fat utilization, leading to body mass reduction. Those animals were more active, and metabolized more fats than those fed with a high proportion of unsaturated fatty acids (="unsaturated diets"). These results contrast with previous studies, which showed a significant effect of fatty acid composition of diets on food preferences and torpor patterns in mammals.
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Huddling facilitates expression of daily torpor in the large Japanese field mouse Apodemus speciosus. Physiol Behav 2014; 133:22-9. [DOI: 10.1016/j.physbeh.2014.04.051] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 04/09/2014] [Accepted: 04/29/2014] [Indexed: 11/22/2022]
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Egginton S, May S, Deveci D, Hauton D. Is cold acclimation of benefit to hibernating rodents? ACTA ACUST UNITED AC 2013; 216:2140-9. [PMID: 23430997 DOI: 10.1242/jeb.079160] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The thermal challenge associated with cold acclimation (CA) and hibernation requires effective cardio-respiratory function over a large range of temperatures. We examined the impact of acute cooling in a cold-naïve hibernator to quantify the presumed improvement in cardio-respiratory dysfunction triggered by CA, and estimate the role of the autonomic nervous system in optimising cardiac and respiratory function. Golden hamsters (Mesocricetus auratus) were held at a 12 h:12 h light:dark photoperiod and room temperature (21°C euthermic control) or exposed to simulated onset of winter in an environmental chamber, by progression to 1 h:23 h light:dark and 4°C over 4 weeks. In vivo acute cooling (core temperature Tb=25°C) in euthermic controls led to a hypotension and bradycardia, but preserved cardiac output. CA induced a hypertension at normothermia (Tb=37°C) but on cooling led to decreases in diastolic pressure below euthermic controls and a decrease in cardiac output, despite an increase in left ventricular conductance. Power spectral analysis of heart rate variability suggested a decline in vagal tone on cooling euthermic hamsters (Tb=25°C). Following CA, vagal tone was increased at Tb=37°C, but declined more quickly on cooling (Tb=25°C) to preserve vagal tone at levels similar to euthermic controls at Tb=37°C. For the isolated heart, CA led to concentric hypertrophy with decreased end-diastolic volume, but with no change in intrinsic heart rate at either 37 or 25°C. Mechanical impairment was noted at 37°C following CA, with peak developed pressure decreased by 50% and peak rate-pressure product decreased by 65%; this difference was preserved at 25°C. For euthermic hearts, coronary flow showed thermal sensitivity, decreasing by 65% on cooling (T=25°C). By contrast, CA hearts had low coronary flow compared with euthermic controls, but with a loss of thermal sensitivity. Together, these observations suggest that CA induced a functional impairment in the myocardium that limits performance of the cardiovascular system at euthermia, despite increased autonomic input to preserve cardiac function. On acute cooling this autonomic control was lost and cardiac performance declined further than for cold-naïve hamsters, suggesting that CA may compromise elements of cardiovascular function to facilitate preservation of those more critical for subsequent rewarming.
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Affiliation(s)
- Stuart Egginton
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Boratyński JS, Rusiński M, Kokurewicz T, Bereszyński A, Wojciechowski MS. Clustering Behavior in Wintering Greater Mouse-Eared BatsMyotis myotis— the Effect of Micro-Environmental Conditions. ACTA CHIROPTEROLOGICA 2012. [DOI: 10.3161/150811012x661738] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Franco M, Contreras C, Cortés P, Chappell MA, Soto-Gamboa M, Nespolo RF. Aerobic power, huddling and the efficiency of torpor in the South American marsupial, Dromiciops gliroides. Biol Open 2012; 1:1178-84. [PMID: 23259051 PMCID: PMC3522878 DOI: 10.1242/bio.20122790] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 08/20/2012] [Indexed: 11/20/2022] Open
Abstract
During periods of cold, small endotherms depend on a continuous supply of food and energy to maintain euthermic body temperature (T(b)), which can be challenging if food is limited. In these conditions, energy-saving strategies are critical to reduce the energetic requirements for survival. Mammals from temperate regions show a wide arrange of such strategies, including torpor and huddling. Here we provide a quantitative description of thermoregulatory capacities and energy-saving strategies in Dromiciops gliroides, a Microbiotherid marsupial inhabiting temperate rain forests. Unlike many mammals from temperate regions, preliminary studies have suggested that this species has low capacity for control and regulation of body temperature, but there is still an incomplete picture of its bioenergetics. In order to more fully understand the physiological capacities of this "living fossil", we measured its scope of aerobic power and the interaction between huddling and torpor. Specifically, we evaluated: (1) the relation between basal (BMR) and maximum metabolic rate (MMR), and (2) the role of huddling on the characteristics of torpor at different temperatures. We found that BMR and MMR were above the expected values for marsupials and the factorial aerobic scope (from [Formula: see text]CO(2)) was 6.0±0.45 (using [Formula: see text]CO(2)) and 6.2±0.23 (using [Formula: see text]O(2)), an unusually low value for mammals. Also, repeatability of physiological variables was non-significant, as in previous studies, suggesting poor time-consistency of energy metabolism. Comparisons of energy expenditure and body temperature (using attached data-loggers) between grouped and isolated individuals showed that at 20°C both average resting metabolic rate and body temperature were higher in groups, essentially because animals remained non-torpid. At 10°C, however, all individuals became torpid and no differences were observed between grouped and isolated individuals. In summary, our study suggests that the main response of Dromiciops gliroides to low ambient temperature is reduced body temperature and torpor, irrespective of huddling. Low aerobic power and low time-consistency of most thermoregulatory traits of Dromiciops gliroides support the idea of poor thermoregulatory abilities in this species.
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Affiliation(s)
- Marcela Franco
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile , Casilla 567, Valdivia , Chile
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Geiser F, Stawski C. Hibernation and torpor in tropical and subtropical bats in relation to energetics, extinctions, and the evolution of endothermy. Integr Comp Biol 2011; 51:337-48. [PMID: 21700575 DOI: 10.1093/icb/icr042] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Torpor, the most effective means of energy conservation available to endotherms, is still widely viewed as a specific adaptation in a few high-latitude, cold-climate endotherms with no adaptive function in warm regions. Nevertheless, a growing number of diverse terrestrial mammals and birds from low latitudes (0-30°), including species from tropical and subtropical regions, are heterothermic and employ torpor. Use of torpor is especially important for bats because they are small, expend large amounts of energy when active, rely on a fluctuating food supply, and have only a limited capacity for storage of fat. Patterns of torpor in tropical/subtropical bats are highly variable, but short bouts of torpor with relatively high body temperatures (T(b)) are most common. Hibernation (a sequence of multiday bouts of torpor) has been reported for free-ranging subtropical tree-dwelling vespertilionids, cave-dwelling hipposiderids, and house-dwelling molossids. The observed range of minimum T(b) is ∼6-30 °C, and the reduction of energy expenditure through the use of torpor, in comparison to normothermic values, ranges from 50 to 99%. Overall, torpor in the tropics/subtropics has been reported for 10 out of the currently recognized 18 bat families, which contain 1079 species, or 96.7% of all bats. Although it is unlikely that all of these are heterothermic, the large majority probably will be. Frequent use of torpor, including hibernation in diverse groups of tropical/subtropical bats, suggests that heterothermy is an ancestral chiropteran trait. Although data especially from the field are still scarce, it is likely that torpor, highly effective in reducing requirements for energy and water even under warm conditions, plays a crucial role in the long-term survival of the majority of small tropical and subtropical bats. Discovering how bats achieve this provides numerous opportunities for exiting new research.
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Affiliation(s)
- Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale NSW 2351, Australia.
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Wojciechowski MS, Jefimow M, Pinshow B. Heterothermy, and the energetic consequences of huddling in small migrating passerine birds. Integr Comp Biol 2011; 51:409-18. [PMID: 21693540 DOI: 10.1093/icb/icr055] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The success of migration of small passerine birds depends largely on effective refueling at stopover sites. In our previous studies, we found that hypothermia facilitates accumulation of fuel at the beginning of a stopover. Later we found that blackcaps, Sylvia atricapilla, might further reduce their energy expenditure by huddling while at rest. Here, we report experimental results supporting our hypothesis that huddling is beneficial to small migrating passerines both from energetic and thermoregulatory points of view. To test this hypothesis we measured metabolic rates and body temperatures of seven blackcaps placed in respirometry chambers overnight, either solitarily or in groups of three or four at ambient temperatures of 5, 10, and 15°C. Concurring with our predictions, huddling blackcaps maintained higher body temperatures than did solitary birds, but had mass-specific metabolic rates lower by ∼30% than those of solitary individuals. Based on our previous studies, we estimated energy savings through huddling to be comparable to energy savings through hypothermia in solitary blackcaps and suggest that huddling may be an important way of saving energy for small passerine birds resting at migratory stopovers. At the same time it might offer the additional benefit of lower risk of predation. In this light, we predict that huddling occurs frequently in nature, leading to significant savings of energy, faster accumulation of fuel, presumably lower risk of becoming a prey, more successful migration, and eventually increased fitness.
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Affiliation(s)
- Michał S Wojciechowski
- Department of Animal Physiology, Institute of General and Molecular Biology, Nicolaus Copernicus University, ul. Gagarina 9, PL 87-100 Toruń, Poland.
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