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Mella VSA, Cooper CE, Karr M, Krockenberger A, Madani G, Webb EB, Krockenberger MB. Hot climate, hot koalas: the role of weather, behaviour and disease on thermoregulation. CONSERVATION PHYSIOLOGY 2024; 12:coae032. [PMID: 38803425 PMCID: PMC11129715 DOI: 10.1093/conphys/coae032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 04/08/2024] [Accepted: 04/30/2024] [Indexed: 05/29/2024]
Abstract
Thermoregulation is critical for endotherms living in hot, dry conditions, and maintaining optimal core body temperature (Tb) in a changing climate is an increasingly challenging task for mammals. Koalas (Phascolarctos cinereus) have evolved physiological and behavioural strategies to maintain homeostasis and regulate their Tb but are thought to be vulnerable to prolonged heat. We investigated how weather, behaviour and disease influence Tb for wild, free-living koalas during summer in north-west New South Wales. We matched Tb with daily behavioural observations in an ageing population where chlamydial disease is prevalent. Each individual koala had similar Tb rhythms (average Tb = 36.4 ± 0.05°C), but male koalas had higher Tb amplitude and more pronounced daily rhythm than females. Disease disrupted the 24-hr circadian pattern of Tb. Koala Tb increased with ambient temperature (Ta). On the hottest day of the study (maximum Ta = 40.8°C), we recorded the highest (Tb = 40.8°C) but also the lowest (Tb = 32.4°C) Tb ever documented for wild koalas, suggesting that they are more heterothermic than previously recognized. This requires individuals to predict days of extreme Ta from overnight and early morning conditions, adjusting Tb regulation accordingly, and it has never been reported before for koalas. The large diel amplitude and low minimum Tb observed suggest that koalas at our study site are energetically and nutritionally compromised, likely due to their age. Behaviour (i.e. tree hugging and drinking water) was not effective in moderating Tb. These results indicate that Ta and koala Tb are strongly interconnected and reinforce the importance of climate projections for predicting the future persistence of koalas throughout their current distribution. Global climate models forecast that dry, hot weather will continue to escalate and drought events will increase in frequency, duration and severity. This is likely to push koalas and other arboreal folivores towards their thermal limit.
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Affiliation(s)
- Valentina S A Mella
- Sydney School of Veterinary Science, The University of Sydney, Sydney, New South Wales 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Christine E Cooper
- School of Molecular and Life Sciences, Curtin University, Perth, Western Australia 6102, Australia
| | - Madeline Karr
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Andrew Krockenberger
- Division of Research and Innovation, James Cook University, Cairns, Queensland 4878, Australia
| | - George Madani
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Elliot B Webb
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
- Department of Planning and Environment, Science, Economics and Insights Division, Parramatta, New South Wales 2150, Australia
| | - Mark B Krockenberger
- Sydney School of Veterinary Science, The University of Sydney, Sydney, New South Wales 2006, Australia
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Kitagawa Y, Maloney SK, Pool KR, Webster D, Ohkura S, Blache D, Ding L. Behavioural and physiological responses to stressors in sheep with temperament classified by genotype or phenotype. Sci Rep 2024; 14:8147. [PMID: 38584170 PMCID: PMC10999442 DOI: 10.1038/s41598-024-58959-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 04/04/2024] [Indexed: 04/09/2024] Open
Abstract
The single nucleotide polymorphism (SNP) rs107856856, located in the tryptophan hydroxylase-2 gene, is associated with the behavioural phenotype for sheep temperament measured at weaning. Here, we tested the association between that SNP and physiological and behavioural responses to stressors in adult sheep. Two groups of adult sheep, one with genotype A/A (calm genotype) and the other with G/G (nervous genotype) in rs107856856, were selected from 160 sheep and were exposed, twice, to an open-field arena and an isolation box test (IBT). During each repeat, the behaviour and physiological responses (cortisol, prolactin, dehydroepiandrosterone [DHEA], brain derived neurotrophic factor [BDNF], characteristics of the response of body temperature, and oxidative stress) were measured. The behavioural and physiological responses of the sheep were compared between genotypes and also between groups classified on their phenotype as assessed by their initial isolation box score ("low responders" and "high responders"). The SNP rs107856856 had some effects on the behavioural phenotype (IBT score) but no effects on the physiological response to stress (cortisol, prolactin, DHEA, BDNF, oxidative stress or changes in body temperature) in the adult sheep, probably because the sheep were exposed, and therefore had adapted, to human contact during their life.
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Affiliation(s)
- Yuri Kitagawa
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, Japan
- School of Agriculture and Environment, M087, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Shane K Maloney
- School of Human Sciences, M309, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Kelsey R Pool
- School of Agriculture and Environment, M087, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Dane Webster
- School of Human Sciences, M309, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Satoshi Ohkura
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, Japan
| | - Dominique Blache
- College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China.
- School of Agriculture and Environment, M087, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia.
| | - Luoyang Ding
- College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China.
- School of Agriculture and Environment, M087, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia.
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Goh G, Vesterdorf K, Fuller A, Blache D, Maloney SK. Optimal sampling interval for characterisation of the circadian rhythm of body temperature in homeothermic animals using periodogram and cosinor analysis. Ecol Evol 2024; 14:e11243. [PMID: 38601852 PMCID: PMC11004550 DOI: 10.1002/ece3.11243] [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: 05/18/2022] [Revised: 03/19/2024] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
Core body temperature (T c) is a critical aspect of homeostasis in birds and mammals and is increasingly used as a biomarker of the fitness of an animal to its environment. Periodogram and cosinor analysis can be used to estimate the characteristics of the circadian rhythm of T c from data obtained on loggers that have limited memory capacity and battery life. The sampling interval can be manipulated to maximise the recording period, but the impact of sampling interval on the output of periodogram or cosinor analysis is unknown. Some basic guidelines are available from signal analysis theory, but those guidelines have never been tested on T c data. We obtained data at 1-, 5- or 10-min intervals from nine avian or mammalian species, and re-sampled those data to simulate logging at up to 240-min intervals. The period of the rhythm was first analysed using the Lomb-Scargle periodogram, and the mesor, amplitude, acrophase and adjusted coefficient of determination (R 2) from the original and the re-sampled data were obtained using cosinor analysis. Sampling intervals longer than 60 min did not affect the average mesor, amplitude, acrophase or adjusted R 2, but did impact the estimation of the period of the rhythm. In most species, the period was not detectable when intervals longer than 120 min were used. In all individual profiles, a 30-min sampling interval modified the values of the mesor and amplitude by less than 0.1°C, and the adjusted R 2 by less than 0.1. At a 30-min interval, the acrophase was accurate to within 15 min for all species except mice. The adjusted R 2 increased as sampling frequency decreased. In most cases, a 30-min sampling interval provides a reliable estimate of the circadian T c rhythm using periodogram and cosinor analysis. Our findings will help biologists to select sampling intervals to fit their research goals.
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Affiliation(s)
- Grace Goh
- School of Human SciencesThe University of Western AustraliaCrawleyWestern AustraliaAustralia
| | - Kristine Vesterdorf
- School of Human SciencesThe University of Western AustraliaCrawleyWestern AustraliaAustralia
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health SciencesUniversity of the WitwatersrandJohannesburgSouth Africa
| | - Dominique Blache
- School of Agriculture and EnvironmentThe University of Western AustraliaCrawleyWestern AustraliaAustralia
| | - Shane K. Maloney
- School of Human SciencesThe University of Western AustraliaCrawleyWestern AustraliaAustralia
- Brain Function Research Group, School of Physiology, Faculty of Health SciencesUniversity of the WitwatersrandJohannesburgSouth Africa
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Botha A, Fuller A, Beechler BR, Combrink HJ, Jolles AE, Maloney SK, Hetem RS. Cold and Hungry: Heterothermy Is Associated with Low Leptin Levels in a Bulk Grazer during a Drought. Physiol Biochem Zool 2023; 96:342-355. [PMID: 37713716 DOI: 10.1086/726162] [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] [Indexed: 09/17/2023]
Abstract
AbstractReduced energy intake can compromise the ability of a mammal to maintain body temperature within a narrow 24-h range, leading to heterothermy. To investigate the main drivers of heterothermy in a bulk grazer, we compared abdominal temperature, body mass, body condition index, and serum leptin levels in 11 subadult Cape buffalo (Syncerus caffer caffer) during a drought year and a nondrought year. Low food availability during the drought year (as indexed by grass biomass, satellite imagery of vegetation greenness, and fecal chlorophyll) resulted in lower body condition index, lower body mass relative to that expected for an equivalent-aged buffalo, and lower leptin levels. The range of 24-h body temperature rhythm was 2°C during the nondrought year and more than double that during the drought year, and this was caused primarily by a lower minimum 24-h body temperature rhythm during the cool dry winter months. After rain fell and vegetation greenness increased, the minimum 24-h body temperature rhythm increased, and the range of 24-h body temperature rhythm was smaller than 2°C. In order of importance, poor body condition, low minimum 24-h air temperature, and low serum leptin levels were the best predictors of the increase in the range of 24-h body temperature rhythm. While the thermoregulatory role of leptin is not fully understood, the association between range of 24-h body temperature rhythm and serum leptin levels provides clues about the underlying mechanism behind the increased heterothermy in large mammals facing food restriction.
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Durunna O, Carroll JA, Dailey JW, Damiran D, Larson KA, Timsit E, Parsons R, Manafiazar G, Lardner HA. Phenotypic and genetic parameters of circadian rhythms from core body temperature profiles and their relationships with beef steers' production efficiency profiles during successive winter feeding periods. Front Genet 2023; 14:1026601. [PMID: 36741324 PMCID: PMC9893500 DOI: 10.3389/fgene.2023.1026601] [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: 08/24/2022] [Accepted: 01/06/2023] [Indexed: 01/20/2023] Open
Abstract
This 2-year study evaluated differences in circadian parameters obtained from measures of core body temperatures using telemetric reticulo-rumen and rectal devices during two winter feeding regimes in western Canada. The study also estimated phenotypic correlations and genetic parameters associated with circadian parameters and other production traits in each feeding regime. Each year, 80 weaned steer calves (initial age: 209 ± 11 days; BW: 264 ± 20 kg) from the same cohort were tested over two successive regimes, Fall-Winter (FW) and Winter-Spring (WS) at Lanigan, Saskatchewan, Canada. The steers received forage-based rations in both regimes where the individual feed intake was measured with automatic feeding units. During the trial, the reticulo-rumen (RTMP) and rectal (RCT) temperatures were simultaneously measured every 5 min using telemetric devices. These were used to calculate the circadian parameters (Midline Estimating Statistic Of Rhythms, amplitude, and acrophase/peak time) for both temperature measures. Growth and efficiency performance traits were also determined for all steers. Each steer was assigned into inefficient, neutral, and efficient classes based on the SD of the residual feed intake (RFI), residual gain (RG), and residual intake and gain (RIG) within each year and feeding regime. Higher (p < 0.0003) RTMP and rectal temperature MESORs were observed in the Fall-Winter compared to the Winter-Spring regime. While the two test regimes were different (p < 0.05) for the majority of the RTMP or RCT temperature parameters, they did not differ (p > 0.10) with the production efficiency profiles. The heritability estimates were higher in FW (0.78 ± 0.18 vs. 0.56 ± 0.26) than WS (0.50 ± 0.18 vs. 0.47 ± 0.22) for the rumen and rectal MESORs, respectively. There were positive genetic correlations between the two regimes for the RTMP (0.69 ± 0.21) and RCT (0.32 ± 0.59). There was a negative correlation (p < 0.001) between body temperature and ambient temperature. The high heritability estimates and genetic correlations for rumen and rectal temperature parameters demonstrate their potential as beef genetic improvement tools of economic traits associated with the parameters. However, there are limited practical implications of using only the core-body temperature as a proxy for production efficiency traits for beef steers during winter.
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Affiliation(s)
- Obioha Durunna
- Department of Applied Research, Lakeland College, Vermilion, AB, Canada,Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada,*Correspondence: Obioha Durunna,
| | | | - Jeff W. Dailey
- USDA ARS Livestock Issues Research Unit, Lubbock, TX, United States
| | - Daalkhaijav Damiran
- Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada
| | - Kathy A. Larson
- Department of Agricultural and Resource Economics, University of Saskatchewan, Saskatoon, SK, Canada
| | - Edouard Timsit
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Rex Parsons
- Australian Centre for Health Services Innovation and Centre for Healthcare Transformation, School of Public Health and Social Work, Faculty of Health, Queensland University of Technology, Kelvin Grove, QLD, Australia
| | - Ghader Manafiazar
- Animal Science and Aquaculture Department, Faculty of Agriculture, Dalhousie University, Halifax, NS, Canada
| | - Herbert A. Lardner
- Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada
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6
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Abecia JA, Luis S, Canto F, Plaza J, Palacios C. Using subcutaneous bio-loggers to monitor circadian rhythmicity of temperature, heart rate and activity in sheep under intensive housing conditions. BIOL RHYTHM RES 2021. [DOI: 10.1080/09291016.2021.2016131] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- José-Alfonso Abecia
- Instituto de Investigación en Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Zaragoza, Spain
| | - Silvia Luis
- Instituto de Investigación en Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Zaragoza, Spain
| | - Francisco Canto
- Instituto de Investigación en Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Zaragoza, Spain
| | - Javier Plaza
- Departamento de Construcción y Agronomía, Facultad de Ciencias Agrarias y Ambientales, Salamanca, Spain
| | - Carlos Palacios
- Departamento de Construcción y Agronomía, Facultad de Ciencias Agrarias y Ambientales, Salamanca, Spain
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7
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Goh GH, Mark PJ, Blache D, Binks D, Parsons R, Rawashdeh O, Maloney SK. Diet-altered body temperature rhythms are associated with altered rhythms of clock gene expression in peripheral tissues in vivo. J Therm Biol 2021; 100:102983. [PMID: 34503769 DOI: 10.1016/j.jtherbio.2021.102983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/25/2021] [Accepted: 04/26/2021] [Indexed: 10/21/2022]
Abstract
Temperature rhythms can act as potent signals for the modulation of the amplitude and phase of clock gene expression in peripheral organs in vitro, but the relevance of the circadian rhythm of core body temperature (Tc) as a modulating signal in vivo has not yet been investigated. Using calorie restriction and cafeteria feeding, we induced a larger and a dampened Tc amplitude, respectively, in male Wistar rats, and investigated the circadian expression profile of the core clock genes Bmal1, Per2, Cry1, and Rev-erbα, the heat-responsive genes heat shock protein 90 (Hsp90) and cold-inducible RNA binding protein (Cirbp), and Pgc1α, Pparα/γ/δ, Glut1/4, and Chop10 in the liver, skeletal muscle, white adipose tissue (WAT), and adrenal glands. Diet-altered Tc rhythms differentially affected the profiles of clock genes, Hsp90, and Cirbp expression in peripheral tissues. Greater Tc amplitudes elicited by calorie restriction were associated with large amplitudes of Hsp90 and Cirbp expression in the liver and WAT, in which larger amplitudes of clock gene expression were also observed. The amplitudes of metabolic gene expression were greater in the WAT, but not in the liver, in calorie-restricted rats. Conversely, diet-altered Tc rhythms were not translated to distinct changes in the amplitude of Hsp90, Cirbp, or clock or metabolic genes in the skeletal muscle or adrenal glands. While it was not possible to disentangle the effects of diet and temperature in this model, taken together with previous in vitro studies, our study presents novel data consistent with the notion that the circadian Tc rhythm can modulate the amplitude of circadian gene expression in vivo. The different responses of Hsp90 and Cirbp in peripheral tissues may be linked to the tissue-specific responses of peripheral clocks to diet and/or body temperature rhythms, but the association with the amplitude of metabolic gene expression is limited to the WAT.
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Affiliation(s)
- Grace H Goh
- School of Human Biology, University of Western Australia, Crawley, 6009, Australia.
| | - Peter J Mark
- School of Human Biology, University of Western Australia, Crawley, 6009, Australia
| | - Dominique Blache
- School of Agriculture and Environment, University of Western Australia, Crawley, WA, 6009, Australia
| | - Daniel Binks
- School of Human Biology, University of Western Australia, Crawley, 6009, Australia
| | - Rex Parsons
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St Lucia, QLD, 4072, Australia
| | - Oliver Rawashdeh
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St Lucia, QLD, 4072, Australia
| | - Shane K Maloney
- School of Human Biology, University of Western Australia, Crawley, 6009, Australia
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8
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Willis RS, Fleming PA, Dunston-Clarke EJ, Barnes AL, Miller DW, Collins T. Animal welfare indicators for sheep during sea transport: The effect of voyage day and time of day. Appl Anim Behav Sci 2021. [DOI: 10.1016/j.applanim.2021.105304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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9
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Fuller A, Mitchell D, Maloney SK, Hetem RS, Fonsêca VFC, Meyer LCR, van de Ven TMFN, Snelling EP. How dryland mammals will respond to climate change: the effects of body size, heat load and a lack of food and water. J Exp Biol 2021; 224:224/Suppl_1/jeb238113. [PMID: 33627465 DOI: 10.1242/jeb.238113] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Mammals in drylands are facing not only increasing heat loads but also reduced water and food availability as a result of climate change. Insufficient water results in suppression of evaporative cooling and therefore increases in body core temperature on hot days, while lack of food reduces the capacity to maintain body core temperature on cold nights. Both food and water shortage will narrow the prescriptive zone, the ambient temperature range over which body core temperature is held relatively constant, which will lead to increased risk of physiological malfunction and death. Behavioural modifications, such as shifting activity between night and day or seeking thermally buffered microclimates, may allow individuals to remain within the prescriptive zone, but can incur costs, such as reduced foraging or increased competition or predation, with consequences for fitness. Body size will play a major role in predicting response patterns, but identifying all the factors that will contribute to how well dryland mammals facing water and food shortage will cope with increasing heat loads requires a better understanding of the sensitivities and responses of mammals exposed to the direct and indirect effects of climate change.
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Affiliation(s)
- Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa .,Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.,Centre for Veterinary Wildlife Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa.,School of Human Sciences, Faculty of Science, University of Western Australia, Crawley 6009, WA, Australia
| | - Shane K Maloney
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa.,School of Human Sciences, Faculty of Science, University of Western Australia, Crawley 6009, WA, Australia
| | - Robyn S Hetem
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa.,School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg 2000, South Africa
| | - Vinicius F C Fonsêca
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa.,Innovation Group of Biometeorology and Animal Welfare (INOBIO-MANERA), Universidade Federal da Paraíba, Areia, 58397000, Brazil
| | - Leith C R Meyer
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa.,Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.,Centre for Veterinary Wildlife Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa
| | - Tanja M F N van de Ven
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa
| | - Edward P Snelling
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa.,Centre for Veterinary Wildlife Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.,Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa
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Refinetti R. Circadian rhythmicity of body temperature and metabolism. Temperature (Austin) 2020; 7:321-362. [PMID: 33251281 PMCID: PMC7678948 DOI: 10.1080/23328940.2020.1743605] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/11/2020] [Accepted: 03/12/2020] [Indexed: 12/19/2022] Open
Abstract
This article reviews the literature on the circadian rhythms of body temperature and whole-organism metabolism. The two rhythms are first described separately, each description preceded by a review of research methods. Both rhythms are generated endogenously but can be affected by exogenous factors. The relationship between the two rhythms is discussed next. In endothermic animals, modulation of metabolic activity can affect body temperature, but the rhythm of body temperature is not a mere side effect of the rhythm of metabolic thermogenesis associated with general activity. The circadian system modulates metabolic heat production to generate the body temperature rhythm, which challenges homeothermy but does not abolish it. Individual cells do not regulate their own temperature, but the relationship between circadian rhythms and metabolism at the cellular level is also discussed. Metabolism is both an output of and an input to the circadian clock, meaning that circadian rhythmicity and metabolism are intertwined in the cell.
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Affiliation(s)
- Roberto Refinetti
- Department of Psychology, University of New Orleans, New Orleans, LA, USA
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11
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Thermoregulatory differences in African mole-rat species from disparate habitats: Responses and limitations. J Therm Biol 2019; 88:102495. [PMID: 32125983 DOI: 10.1016/j.jtherbio.2019.102495] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/06/2019] [Accepted: 12/25/2019] [Indexed: 12/20/2022]
Abstract
Individuals and populations possess physiological adaptations to survive local environmental conditions. To occur in different regions where ambient temperature varies, animals must adopt appropriate thermoregulatory mechanisms. Failure to adjust to environmental challenges may result in species distributional range shifts or decreased viability. African mole-rats (Bathyergidae) occupy various habitats in sub-Saharan Africa from deserts to montane regions to mesic coastal areas. We examined thermoregulatory characteristics of three African mole-rat species originating from disparate (montane, savannah, and arid/semi-arid) habitats. Animals were exposed to various ambient temperatures, whilst core body temperature and the surface temperature of different body parts were measured. Oxygen consumption was determined as a measure of heat production. Core body temperatures of Natal (montane) mole-rats (Cryptomys hottentotus natalensis) increased significantly at ambient temperatures >24.5 °C, while those of the highveld (Cryptomys hottentotus pretoriae) (savannah) and Damaraland (Fukomys damarensis) (arid/semi-arid) mole-rats remained within narrower ranges. In terms of surface temperature variation, while pedal surfaces were important in regulating heat loss in Natal and Damaraland mole-rats at high ambient temperatures, the ventral surface was important for heat dissipation in Damaraland and highveld mole-rats. This study provides evidence of the variation and limitations of thermo-physiological mechanisms for three mole-rat species relative to their habitats. Information on physiological adaptations to particular habitats may inform predictive modelling of species movements, declines, and extinctions in response to a changing environment, such as climate change.
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12
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Nascimento ST, Maia ASC, de França Carvalho Fonsêca V, Nascimento CCN, de Carvalho MD, da Graça Pinheiro M. Physiological responses and thermal equilibrium of Jersey dairy cows in tropical environment. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2019; 63:1487-1496. [PMID: 31147777 DOI: 10.1007/s00484-019-01734-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 03/14/2019] [Accepted: 05/14/2019] [Indexed: 06/09/2023]
Abstract
Long-term assessments of thermal responses of housed Jersey cows raised in tropical conditions were performed to investigate the effect of climate environment on their physiological performance and thermal equilibrium. Twelve Jersey dairy cows with 326.28 ± 30 kg of body weight, 17.66 ± 1.8 of milk yield, and 165.5 ± 6.8 of days in milking were assigned in two 12 × 12 Latin square designs. Air temperature, relative humidity, partial vapor pressure, direct and diffuse short-wave solar radiation and black globe temperature under the shade, and direct sunlight were recorded. Physiological responses as respiratory rate (RR, breaths min-1), ventilation (VE, L s-1), proportion (%) of oxygen (O2) and carbon dioxide (CO2), saturation pressure (PS{TEXH}), and air temperature (TEXH, °C) of the exhaled air were assessed protected from solar radiation and rain. Rectal temperature (TR, °C), skin temperature (TEP, °C), and hair coat surface temperature (TS, °C) were also recorded. The thermal equilibrium was determined from biophysical equations according to the principles of the energy conservation law in a control volume. Exploratory and confirmatory analyses were performed from principal components and by the least square method, respectively. The cows were evaluated under range of ambient air temperature from 26 to 35 °C, relative humidity from 27 to 89%, and short-wave radiation from 0 to 729 W m-2. Exploratory and confirmatory analyses demonstrated that a similar level of nocturnal and diurnal air temperatures evoked distinct (P < 0.05) responses for rectal (TR, °C) and skin (TEP, °C) temperatures, ventilation (VE, L s-1), tidal volume (TV, L breaths-1), and oxygen consumption (∆O2, %) and carbon dioxide output (∆CO2, %), clearly revealing an endogenous rhythm dependence. In conclusion, these findings clarify how the circadian rhythmicity of the thermal environment and animal's biological clock dictate dynamics of heat generated by metabolism, dissipated to the environment and physiological parameters of the housed Jersey cows raised in tropical condition; therefore, it is fundamental to help us to understand how the Jersey dairy cows under tropics are affected by the climatic conditions, leading to better ways of the environmental management.
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Affiliation(s)
- Sheila Tavares Nascimento
- Faculty of Agronomy and Veterinary Science, University of Brasília, Darcy Ribeiro Campus, Brasília, DF, 70910-900, Brazil.
| | - Alex Sandro Campos Maia
- Innovation Group of Biometeorology, Behavior and Animal Welfare (INOBIO-MANERA), Biometorology Laboratory, Sao Paulo State University, Jaboticabal, Brazil
| | - Vinícius de França Carvalho Fonsêca
- Innovation Group of Biometeorology, Behavior and Animal Welfare (INOBIO-MANERA), Biometorology Laboratory, Sao Paulo State University, Jaboticabal, Brazil
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
| | - Carolina Cardoso Nagib Nascimento
- Innovation Group of Biometeorology, Behavior and Animal Welfare (INOBIO-MANERA), Biometorology Laboratory, Sao Paulo State University, Jaboticabal, Brazil
| | | | - Maria da Graça Pinheiro
- Agência Paulista de Tecnologia dos Agronegócios, 2419 Bandeirantes Avenue, Ribeirão Preto, SP, 14030-670, Brazil
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13
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Maloney SK, Marsh MK, McLeod SR, Fuller A. Heterothermy is associated with reduced fitness in wild rabbits. Biol Lett 2018; 13:rsbl.2017.0521. [PMID: 29212751 DOI: 10.1098/rsbl.2017.0521] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 11/14/2017] [Indexed: 11/12/2022] Open
Abstract
An increase in variation in the 24 h pattern of body temperature (heterothermy) in mammals can be induced by energy and water deficits. Since performance traits such as growth and reproduction also are impacted by energy and water balance, we investigated whether the characteristics of the body temperature rhythm provide an indication of the reproductive success of an individual. We show that the amplitude of the daily rhythm of body temperature in wild rabbits (Oryctolagus cuniculus) prior to breeding is inversely related to the number of pregnancies in the subsequent seven months, while the minimum daily body temperature is positively correlated to the number of pregnancies. Because reproductive output could be predicted from characteristics of the core body temperature rhythm prior to the breeding season, we propose that the pattern of the 24 h body temperature rhythm could provide an index of animal fitness in a given environment.
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Affiliation(s)
- Shane K Maloney
- School of Human Sciences, University of Western Australia, Stirling Highway, Crawley 6009, Australia .,Brain Function Research Group, School of Physiology, University of the Witwatersrand, Medical School, 7 York Road, Parktown 2193, South Africa
| | - Maija K Marsh
- Environment Department, University of York, Heslington, York YO10 5DD, UK
| | - Steven R McLeod
- Vertebrate Pest Research Unit, New South Wales Department of Primary Industries, Forest Road, Orange, New South Wales 2800, Australia
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Medical School, 7 York Road, Parktown 2193, South Africa
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14
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Crew RC, Waddell BJ, Maloney SK, Mark PJ. Diet-induced obesity reduces core body temperature across the estrous cycle and pregnancy in the rat. Chronobiol Int 2018; 35:1077-1087. [PMID: 29659304 DOI: 10.1080/07420528.2018.1458035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Obesity during pregnancy causes adverse maternal and fetal health outcomes and programs offspring for adult-onset diseases, including cardiovascular disease. Obesity also disrupts core body temperature (Tc) regulation in nonpregnant rodents; however, it is unknown whether obesity alters normal maternal Tc adaptations to pregnancy. Since Tc is influenced by the circadian system, and both obesity and pregnancy alter circadian biology, it was hypothesized that obesity disrupts the normal rhythmic patterns of Tc before and during gestation. Obesity was induced by cafeteria (CAF) feeding in female Wistar rats for 8 weeks prior to and during gestation, whereas control (CON) animals had free access to chow. Intraperitoneal temperature loggers measured daily Tc profiles throughout the study, while maternal body composition and leptin levels were assessed near term. Daily temperature profiles were examined for rhythmic features (mesor, amplitude and acrophase) by cosine regression analysis. CAF animals exhibited increased fat mass (93%) and associated hyperleptinemia (3.2-fold increase) compared to CON animals. CAF consumption reduced the average Tc (by up to 0.29°C) across the estrous cycle and most of pregnancy; however, Tc for CAF and CON animals converged toward the end of gestation. Obesity reduced the amplitude of Tc rhythms at estrus and proestrus and on day 8 of pregnancy, but increased the amplitude at day 20 of pregnancy. Photoperiod analysis revealed that obesity reduced Tc exclusively in the light period during pre-pregnancy but only during the dark period in late gestation. In conclusion, obesity alters rhythmic Tc profiles and reduces the magnitude of the Tc decline late in rat gestation, which may have implications for maternal health and fetal development.
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Affiliation(s)
- Rachael C Crew
- a School of Human Sciences , The University of Western Australia , Perth , Australia
| | - Brendan J Waddell
- a School of Human Sciences , The University of Western Australia , Perth , Australia
| | - Shane K Maloney
- a School of Human Sciences , The University of Western Australia , Perth , Australia
| | - Peter J Mark
- a School of Human Sciences , The University of Western Australia , Perth , Australia
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15
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Ayo JO, Makeri HK, Minka NS, Aluwong T. Circadian rhythms of biomarkers of oxidative stress and their characteristics in broiler chickens reared under natural light/dark cycle. BIOL RHYTHM RES 2017. [DOI: 10.1080/09291016.2017.1336880] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Joseph Olusegun Ayo
- Faculty of Veterinary Medicine, Department of Physiology, Ahmadu Bello University, Zaria, Nigeria
| | - Harold Kuta Makeri
- Division of Agricultural Colleges, Department of Animal Health and Husbandry, College of Agriculture and Animal Science, Ahmadu Bello University, Mando-Kaduna, Nigeria
| | - Ndazo Salka Minka
- Faculty of Veterinary Medicine, Department of Physiology, Ahmadu Bello University, Zaria, Nigeria
| | - Tagang Aluwong
- Faculty of Veterinary Medicine, Department of Physiology, Ahmadu Bello University, Zaria, Nigeria
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16
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Davimes JG, Alagaili AN, Bertelsen MF, Mohammed OB, Hemingway J, Bennett NC, Manger PR, Gravett N. Temporal niche switching in Arabian oryx (Oryx leucoryx): Seasonal plasticity of 24h activity patterns in a large desert mammal. Physiol Behav 2017; 177:148-154. [PMID: 28431978 DOI: 10.1016/j.physbeh.2017.04.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 11/19/2022]
Abstract
The Arabian oryx, a moderately large mammal that inhabits a harsh desert environment, has been shown to exhibit seasonal variations in activity and inactivity patterns. Here we analyzed the continuous year-round activity patterns of twelve free-roaming Arabian oryx under natural conditions from two varying desert environments in Saudi Arabia using abdominally implanted activity meters. We simultaneously recorded weather parameters at both sites to determine whether environmental factors are responsible for temporal niche switching as well as the seasonal structuring and timing of this behavioural plasticity. Our results demonstrate that Arabian oryx undergo temporal niche switching of 24h activity patterns at a seasonal level and exhibit distinct nocturnal/crepuscular activity during summer, diurnal activity during winter and intermittent patterns of behaviour during the transitional seasons of autumn and spring. In addition, the oryx exhibited inter- and intra-seasonal variations in the temporal budgeting of 24h activity patterns. Strong relationships with both photoperiod and ambient temperatures were found and in some instances suggested that increasing ambient temperatures are a primary driving force behind seasonal shifts in activity patterns. These adaptive patterns may be dictated by the availability of food and water, which in turn are strongly influenced by seasonal climate variations. Overall, the adaptive responses of free-roaming Arabian oryx in such harsh and non-laboratorial conditions provide a framework for comparing wild populations as well as aiding conservation efforts.
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Affiliation(s)
- Joshua G Davimes
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193 Johannesburg, South Africa
| | - Abdulaziz N Alagaili
- KSU Mammals Research Chair, Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | - Osama B Mohammed
- KSU Mammals Research Chair, Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Jason Hemingway
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193 Johannesburg, South Africa
| | - Nigel C Bennett
- KSU Mammals Research Chair, Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; South African Research Chair of Mammal Behavioural Ecology and Physiology, University of Pretoria, Pretoria 0002, South Africa
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193 Johannesburg, South Africa
| | - Nadine Gravett
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193 Johannesburg, South Africa.
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17
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Towards a mechanistic understanding of the responses of large terrestrial mammals to heat and aridity associated with climate change. ACTA ACUST UNITED AC 2016. [DOI: 10.1186/s40665-016-0024-1] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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18
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Maloney SK. Energy signaling in obese mice delays the impact of fasting on thermoregulation. Temperature (Austin) 2016; 3:197-198. [PMID: 27857949 PMCID: PMC4964989 DOI: 10.1080/23328940.2016.1139961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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19
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Hetem RS, Maloney SK, Fuller A, Mitchell D. Heterothermy in large mammals: inevitable or implemented? Biol Rev Camb Philos Soc 2014; 91:187-205. [PMID: 25522232 DOI: 10.1111/brv.12166] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 10/24/2014] [Accepted: 11/11/2014] [Indexed: 11/26/2022]
Abstract
Advances in biologging techniques over the past 20 years have allowed for the remote and continuous measurement of body temperatures in free-living mammals. While there is an abundance of literature on heterothermy in small mammals, fewer studies have investigated the daily variability of body core temperature in larger mammals. Here we review measures of heterothermy and the factors that influence heterothermy in large mammals in their natural habitats, focussing on large mammalian herbivores. The mean 24 h body core temperatures for 17 species of large mammalian herbivores (>10 kg) decreased by ∼1.3°C for each 10-fold increase in body mass, a relationship that remained significant following phylogenetic correction. The degree of heterothermy, as measured by the 24 h amplitude of body core temperature rhythm, was independent of body mass and appeared to be driven primarily by energy and water limitations. When faced with the competing demands of osmoregulation, energy acquisition and water or energy use for thermoregulation, large mammalian herbivores appear to relax the precision of thermoregulation thereby conserving body water and energy. Such relaxation may entail a cost in that an animal moves closer to its thermal limits for performance. Maintaining homeostasis requires trade-offs between regulated systems, and homeothermy apparently is not accorded the highest priority; large mammals are able to maintain optimal homeothermy only if they are well nourished, hydrated, and not compromised energetically. We propose that the amplitude of the 24 h rhythm of body core temperature provides a useful index of any compromise experienced by a free-living large mammal and may predict the performance and fitness of an animal.
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Affiliation(s)
- Robyn S Hetem
- Brain Function Research Group, School of Physiology, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa
| | - Shane K Maloney
- Brain Function Research Group, School of Physiology, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa.,School of Anatomy, Physiology, and Human Biology, University of Western Australia, Crawley, 6009, Australia
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, Faculty of Health Science, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa
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20
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Hetem RS, Fuller A, Maloney SK, Mitchell D. Responses of large mammals to climate change. Temperature (Austin) 2014; 1:115-27. [PMID: 27583293 PMCID: PMC4977165 DOI: 10.4161/temp.29651] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 07/15/2014] [Accepted: 07/19/2014] [Indexed: 12/04/2022] Open
Abstract
Most large terrestrial mammals, including the charismatic species so important for ecotourism, do not have the luxury of rapid micro-evolution or sufficient range shifts as strategies for adjusting to climate change. The rate of climate change is too fast for genetic adaptation to occur in mammals with longevities of decades, typical of large mammals, and landscape fragmentation and population by humans too widespread to allow spontaneous range shifts of large mammals, leaving only the expression of latent phenotypic plasticity to counter effects of climate change. The expression of phenotypic plasticity includes anatomical variation within the same species, changes in phenology, and employment of intrinsic physiological and behavioral capacity that can buffer an animal against the effects of climate change. Whether that buffer will be realized is unknown, because little is known about the efficacy of the expression of plasticity, particularly for large mammals. Future research in climate change biology requires measurement of physiological characteristics of many identified free-living individual animals for long periods, probably decades, to allow us to detect whether expression of phenotypic plasticity will be sufficient to cope with climate change.
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Affiliation(s)
- Robyn S Hetem
- Brain Function Research Group; School of Physiology; University of the Witwatersrand; Faculty of Health Science; Parktown, South Africa
| | - Andrea Fuller
- Brain Function Research Group; School of Physiology; University of the Witwatersrand; Faculty of Health Science; Parktown, South Africa
| | - Shane K Maloney
- Brain Function Research Group; School of Physiology; University of the Witwatersrand; Faculty of Health Science; Parktown, South Africa
- School of Anatomy, Physiology, and Human Biology; University of Western Australia; Crawley, Australia
| | - Duncan Mitchell
- Brain Function Research Group; School of Physiology; University of the Witwatersrand; Faculty of Health Science; Parktown, South Africa
- School of Anatomy, Physiology, and Human Biology; University of Western Australia; Crawley, Australia
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21
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Lubbe A, Hetem RS, McFarland R, Barrett L, Henzi PS, Mitchell D, Meyer LCR, Maloney SK, Fuller A. Thermoregulatory plasticity in free-ranging vervet monkeys, Chlorocebus pygerythrus. J Comp Physiol B 2014; 184:799-809. [PMID: 24938639 DOI: 10.1007/s00360-014-0835-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 05/12/2014] [Accepted: 05/28/2014] [Indexed: 11/27/2022]
Abstract
We used implanted miniature data loggers to obtain the first measurements of body temperature from a free-ranging anthropoid primate. Vervet monkeys (Chlorocebus pygerythrus) living in a highly seasonal, semi-arid environment maintained a lower mean 24-h body temperature in winter (34.6 ± 0.5 °C) than in summer (36.2 ± 0.1 °C), and demonstrated increased heterothermy (as indexed by the 24-h amplitude of their body temperature rhythm) in response to proximal environmental stressors. The mean 24-h amplitude of the body temperature rhythm in summer (2.5 ± 0.1 °C) was lower than that in winter (3.2 ± 0.4 °C), with the highest amplitude for an individual monkey (5.6 °C) recorded in winter. The higher amplitude of the body temperature rhythm in winter was a consequence primarily of lower 24-h minimum body temperatures during the nocturnal phase, when monkeys were inactive. These low minimum body temperatures were associated with low black globe temperature (GLMM, β = 0.046, P < 0.001), short photoperiod (β = 0.010, P < 0.001) and low rainfall over the previous 2 months, which we used as a proxy for food availability (β = 0.001, P < 0.001). Despite the lower average winter minimum body temperatures, there was no change in the lower modal body temperature between winter and summer. Therefore, unlike the regulated physiological adjustments proposed for torpor or hibernation, these minimum winter body temperatures did not appear to reflect a regulated reduction in body temperature. The thermoregulatory plasticity nevertheless may have fitness benefits for vervet monkeys.
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Affiliation(s)
- Alwyn Lubbe
- Brain Function Research Group, Faculty of Health Sciences, School of Physiology, University of the Witwatersrand, 7 York Road, Medical School, Parktown, Johannesburg, 2193, South Africa,
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22
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Fuller A, Hetem RS, Maloney SK, Mitchell D. Adaptation to Heat and Water Shortage in Large, Arid-Zone Mammals. Physiology (Bethesda) 2014; 29:159-67. [DOI: 10.1152/physiol.00049.2013] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although laboratory studies of large mammals have revealed valuable information on thermoregulation, such studies cannot predict accurately how animals respond in their natural habitats. Through insights obtained on thermoregulatory behavior, body temperature variability, and selective brain cooling in free-living mammals, we show here how we can better understand the physiological capacity of large mammals to cope with hotter and drier arid-zone habitats likely with climate change.
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Affiliation(s)
- Andrea Fuller
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; and
| | - Robyn S. Hetem
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; and
| | - Shane K. Maloney
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; and
- School of Anatomy, Physiology, and Human Biology, University of Western Australia, Perth, Australia
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa; and
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