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Metcalfe NB, Bellman J, Bize P, Blier PU, Crespel A, Dawson NJ, Dunn RE, Halsey LG, Hood WR, Hopkins M, Killen SS, McLennan D, Nadler LE, Nati JJH, Noakes MJ, Norin T, Ozanne SE, Peaker M, Pettersen AK, Przybylska-Piech A, Rathery A, Récapet C, Rodríguez E, Salin K, Stier A, Thoral E, Westerterp KR, Westerterp-Plantenga MS, Wojciechowski MS, Monaghan P. Solving the conundrum of intra-specific variation in metabolic rate: A multidisciplinary conceptual and methodological toolkit: New technical developments are opening the door to an understanding of why metabolic rate varies among individual animals of a species: New technical developments are opening the door to an understanding of why metabolic rate varies among individual animals of a species. Bioessays 2023; 45:e2300026. [PMID: 37042115 DOI: 10.1002/bies.202300026] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 04/13/2023]
Abstract
Researchers from diverse disciplines, including organismal and cellular physiology, sports science, human nutrition, evolution and ecology, have sought to understand the causes and consequences of the surprising variation in metabolic rate found among and within individual animals of the same species. Research in this area has been hampered by differences in approach, terminology and methodology, and the context in which measurements are made. Recent advances provide important opportunities to identify and address the key questions in the field. By bringing together researchers from different areas of biology and biomedicine, we describe and evaluate these developments and the insights they could yield, highlighting the need for more standardisation across disciplines. We conclude with a list of important questions that can now be addressed by developing a common conceptual and methodological toolkit for studies on metabolic variation in animals.
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Affiliation(s)
- Neil B Metcalfe
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Jakob Bellman
- Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Pierre Bize
- Swiss Ornithological Institute, Sempach, Switzerland
| | - Pierre U Blier
- Département de Biologie, Université de Québec à Rimouski, Rimouski, Canada
| | - Amélie Crespel
- Department of Biology, University of Turku, Turku, Finland
| | - Neal J Dawson
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Ruth E Dunn
- Lancaster Environment Centre, University of Lancaster, Lancaster, UK
| | - Lewis G Halsey
- School of Life and Health Sciences, University of Roehampton, London, UK
| | - Wendy R Hood
- Department of Biological Sciences, Auburn University, Auburn, USA
| | - Mark Hopkins
- School of Food Science and Nutrition, Leeds University, Leeds, UK
| | - Shaun S Killen
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Darryl McLennan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Lauren E Nadler
- Ocean and Earth Science, NOC, University of Southampton, Southampton, UK
| | - Julie J H Nati
- Ocean Sciences Center, Memorial University of Newfoundland, St John's, Canada
| | - Matthew J Noakes
- School of Animal, Plant, and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Tommy Norin
- DTU Aqua: National Institute of Aquatic Resources, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Susan E Ozanne
- Wellcome-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | | | - Amanda K Pettersen
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
- School of Life & Environmental Sciences, The University of Sydney, Sydney, Australia
| | - Anna Przybylska-Piech
- Department of Vertebrate Zoology & Ecology, Nicolaus Copernicus University, Toruń, Poland
| | - Alann Rathery
- School of Life and Health Sciences, University of Roehampton, London, UK
| | - Charlotte Récapet
- Universite de Pau et des Pays de l'Adour, E2S UPPA, INRAE, ECOBIOP, Saint-Pée-sur-, Nivelle, France
| | - Enrique Rodríguez
- Department of Genetics, Evolution & Environment, University College London, London, UK
| | - Karine Salin
- IFREMER, Univ Brest, CNRS, IRD, Laboratory of Environmental Marine Sciences, Plouzané, France
| | - Antoine Stier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne, France
| | - Elisa Thoral
- Department of Biology, Lund University, Lund, Sweden
| | - Klaas R Westerterp
- Department of Nutrition & Movement Sciences, Maastricht University, Maastricht, The Netherlands
| | | | - Michał S Wojciechowski
- Department of Vertebrate Zoology & Ecology, Nicolaus Copernicus University, Toruń, Poland
| | - Pat Monaghan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
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Noakes MJ, Przybylska-Piech AS, Wojciechowski MS, Jefimow M. Is torpor a water conservation strategy? Heterothermic responses to acute water and food deprivation are repeatable among individuals of Phodopus sungorus. J Therm Biol 2022; 109:103321. [DOI: 10.1016/j.jtherbio.2022.103321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/01/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022]
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Maggini I, Noakes MJ, Hawkes LA, Hegemann A. Editorial: Ecophysiological adaptations associated with animal migration. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1022173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Czenze ZJ, Noakes MJ, Wojciechowski MS. Home is where the heat is: Thermoregulation of European bats inhabiting artificial roosts and the threat of heat waves. J Appl Ecol 2022. [DOI: 10.1111/1365-2664.14230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Zenon J. Czenze
- Centre for Behavioural and Physiological Ecology University of New England Armidale NSW Australia
| | - Matthew J. Noakes
- Department of Vertebrate Zoology and Ecology Nicolaus Copernicus University Toruń Poland
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Noakes MJ, McKechnie AE, Brigham RM. Interspecific variation in heat tolerance and evaporative cooling capacity among sympatric temperate-latitude bats. CAN J ZOOL 2021. [DOI: 10.1139/cjz-2020-0276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that interspecific variation in chiropteran heat tolerance and evaporative cooling capacity is correlated with day-roost microclimates, using three vespertilionid bats that occur sympatrically during summer in Saskatchewan, Canada. We predicted that hoary bats (Lasiurus cinereus (Palisot de Beauvois, 1796); ∼22 g) would have higher heat tolerance than little brown bats (Myotis lucifugus (Le Conte, 1831); ∼7 g) and silver-haired bats (Lasionycteris noctivagans (Le Conte, 1831); ∼13 g), as the latter two species roost in tree crevices or cavities that are more thermally buffered than the foliage roosts of hoary bats. We measured core body temperature (Tb; passive integrated transponder tags), evaporative water loss, and resting metabolic rate (flow-through respirometry) while exposing individuals to a stepped profile of increasing air temperature (Ta) from ∼30 °C in ∼2 °C increments. Experiments were terminated when individuals became hyperthermic (Tb ≈ 42.5 °C), with maximum Ta (Ta,max) ranging from 42.0 to 49.7 °C. As predicted, hoary bats had the highest heat tolerance and evaporative cooling capacity, reaching Ta,max ∼2.4 and 1.2 °C higher than little brown and silver-haired bats, respectively. Our results are consistent with the hypothesis that heat tolerance of bats is correlated with roost microclimates, although interspecific variation in body mass and phylogeny may confound these conclusions.
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Affiliation(s)
- Matthew J. Noakes
- Department of Vertebrate Zoology and Ecology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, ul. Lwowska 1, 87-100 Toruń, Poland
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, Gauteng, 0002, South Africa
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
| | - Andrew E. McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria, Gauteng, 0001, South Africa
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, Gauteng, 0002, South Africa
| | - R. Mark Brigham
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
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Green DM, McGuire LP, Vanderwel MC, Willis CKR, Noakes MJ, Bohn SJ, Green EN, Brigham RM. Local trends in abundance of migratory bats across 20 years. J Mammal 2021. [DOI: 10.1093/jmammal/gyaa154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Abstract
Hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans) are species of conservation concern because of the documented annual mortality that occurs at wind energy facilities. Several recent studies have predicted continental-scale declines of hoary bat populations due to interactions with wind turbines. We predicted a decrease in captures at a summer site over 20 years where researchers have captured bats using generally consistent methods. We developed a hierarchical Bayesian model to estimate the relative change in the expected number of captures while controlling for time of year, temperature, and netting effort. We found no decrease in the number of captures for either species. We suggest that the lack of decrease observed at our study site may be a result of compensatory immigration, despite potential broader-scale population declines.
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Affiliation(s)
- Dana M Green
- Department of Biology, Laboratory Building LB109, University of Regina, Regina, SK, Canada
| | - Liam P McGuire
- Department of Biological Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Mark C Vanderwel
- Department of Biology, Laboratory Building LB248, University of Regina, Regina, SK, Canada
| | - Craig K R Willis
- Department of Biology and Centre for Forest Inter-Disciplinary Research (C-FIR), University of Winnipeg, Winnipeg, MB, Canada
| | - Matthew J Noakes
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
| | - Shelby J Bohn
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Eric N Green
- Department of Biology, Laboratory Building LB109, University of Regina, Regina, SK, Canada
| | - R Mark Brigham
- Department of Biology, Laboratory Building LB109, University of Regina, Regina, SK, Canada
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Noakes MJ, McKechnie AE. Phenotypic flexibility of metabolic rate and evaporative water loss does not vary across a climatic gradient in an Afrotropical passerine bird. J Exp Biol 2020; 223:jeb220137. [PMID: 32165435 DOI: 10.1242/jeb.220137] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/02/2020] [Indexed: 12/30/2022]
Abstract
Small birds inhabiting northern temperate and boreal latitudes typically increase metabolic rates during cold winters or acclimation to low air temperatures (Taccl). Recent studies suggest considerable variation in patterns of seasonal metabolic acclimatization in birds from subtropical and tropical regions with milder winters, but there remains a dearth of acclimation studies investigating metabolic flexibility among lower-latitude birds. We used short-term thermal acclimation experiments to investigate phenotypic flexibility in basal metabolic rate (BMR), thermoneutral evaporative water loss (EWL) and summit metabolism (Msum) in three populations of white-browed sparrow-weavers (Plocepasser mahali) along a climatic and aridity gradient. We allocated individuals to one of three Taccl treatments (5, 20 and 35°C; n=11 per population per Taccl) for 28 days, and measured post-acclimation BMR, EWL and Msum using flow-through respirometry. Our data reveal the expected pattern of lower BMR and EWL (∼12% and 25% lower, respectively) in birds at Taccl=35°C compared with cooler Taccl treatments, as observed in previous acclimation studies on subtropical birds. We found no variation in the reaction norms of BMR and EWL among populations in response to acclimation, suggesting previously documented differences in seasonal BMR acclimatization are the result of phenotypic flexibility. In contrast to higher-latitude species, Msum did not significantly vary in response to thermal acclimation. These findings support the idea that factors other than enhancing cold tolerance may be driving patterns of metabolic variation in subtropical birds.
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Affiliation(s)
- Matthew J Noakes
- DST-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0001, South Africa
| | - Andrew E McKechnie
- DST-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0001, South Africa
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria 0001, South Africa
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Noakes MJ, Karasov WH, McKechnie AE. Seasonal variation in body composition in an Afrotropical passerine bird: increases in pectoral muscle mass are, unexpectedly, associated with lower thermogenic capacity. J Comp Physiol B 2020; 190:371-380. [PMID: 32189062 DOI: 10.1007/s00360-020-01273-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 02/22/2020] [Accepted: 03/02/2020] [Indexed: 11/26/2022]
Abstract
Phenotypic flexibility in avian metabolic rates and body composition have been well-studied in high-latitude species, which typically increase basal metabolic rate (BMR) and summit metabolism (Msum) when acclimatized to winter conditions. Patterns of seasonal metabolic acclimatization are more variable in lower-latitude birds that experience milder winters, with fewer studies investigating adjustments in avian organ and muscle masses in the context of metabolic flexibility in these regions. We quantified seasonal variation (summer vs winter) in the masses of organs and muscles frequently associated with changes in BMR (gizzard, intestines and liver) and Msum (heart and pectoral muscles), in white-browed sparrow-weavers (Plocepasser mahali). We also measured pectoral muscle thickness using a portable ultrasound system to determine whether we could non-lethally estimate muscle size. A concurrent study measured seasonal changes in BMR and Msum in the same population of sparrow-weavers, but different individuals. There was no seasonal variation in the dry masses of the gizzard, intestines or liver of sparrow-weavers, and during the same period, BMR did not vary seasonally. We found significantly higher heart (~ 18% higher) and pectoral muscle (~ 9% higher) dry mass during winter, although ultrasound measurements did not detect seasonal changes in pectoral muscle size. Despite winter increases in pectoral muscle mass, Msum was ~ 26% lower in winter compared to summer. To the best of our knowledge, this is the first study to report an increase in avian pectoral muscle mass but a concomitant decrease in thermogenic capacity.
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Affiliation(s)
- Matthew J Noakes
- DST-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002, South Africa
| | - William H Karasov
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, USA
| | - Andrew E McKechnie
- DST-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002, South Africa.
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria, South Africa.
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Noakes MJ, McKechnie AE. Seasonal Metabolic Acclimatization Varies in Direction and Magnitude among Years in Two Arid-Zone Passerines. Physiol Biochem Zool 2020; 93:140-152. [DOI: 10.1086/707679] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Noakes MJ, McKechnie AE. Reaction norms for heat tolerance and evaporative cooling capacity do not vary across a climatic gradient in a passerine bird. Comp Biochem Physiol A Mol Integr Physiol 2019; 236:110522. [PMID: 31278988 DOI: 10.1016/j.cbpa.2019.06.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/02/2019] [Accepted: 06/27/2019] [Indexed: 11/25/2022]
Abstract
There is increasing evidence for considerable phenotypic flexibility in endotherm thermal physiology, a phenomenon with far-reaching implications for the evolution of traits related to heat tolerance. Numerous studies have documented intraspecific variation in avian thermoregulatory traits, but few have revealed the shapes of thermoregulatory reaction norms or how these might vary among populations. We investigated phenotypic flexibility in the ability of a model Afrotropical passerine bird (the white-browed sparrow-weaver, Plocepasser mahali) to handle high air temperatures (Ta). We allocated birds from three sites varying by ~ 11 °C in mean daily summer maximum Ta to three acclimation temperature (Taccl) treatments (daytime Taccl ≈ 30 °C, 36 °C or 42 °C respectively; n ≈ 10 per site per Taccl). After an acclimation period of 30 days, heat tolerance and evaporative cooling capacity was quantified by exposing birds to progressively higher Ta until they approached severe hyperthermia (body temperature [Tb] = 44.5 °C; Ta range: 38-54 °C). We measured metabolic rate and evaporative water loss using open flow-through respirometry, and Tb using temperature-sensitive passive-integrated transponder tags. Hyperthermia threshold Ta (Ta,HT) was significantly higher and Tb significantly lower in birds acclimated to the hottest Taccl compared to those from milder acclimation treatments. Population (i.e., site of capture) was not a significant predictor of any thermoregulatory variables or hyperthermia threshold Ta (Ta,HT) after acclimation, revealing that the shape of reaction norms for heat tolerance and evaporative cooling capacity does not vary among these three populations.
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Affiliation(s)
- Matthew J Noakes
- DST-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
| | - Andrew E McKechnie
- DST-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa; South African Research Chair in Conservation Physiology, National Zoological Garden, South African National Biodiversity Institute, Pretoria, South Africa.
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van Dyk M, Noakes MJ, McKechnie AE. Interactions between humidity and evaporative heat dissipation in a passerine bird. J Comp Physiol B 2019; 189:299-308. [DOI: 10.1007/s00360-019-01210-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/14/2019] [Accepted: 02/17/2019] [Indexed: 12/01/2022]
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Noakes MJ, Wolf BO, McKechnie AE. Seasonal Metabolic Acclimatization Varies in Direction and Magnitude among Populations of an Afrotropical Passerine Bird. Physiol Biochem Zool 2017; 90:178-189. [DOI: 10.1086/689030] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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McKechnie AE, Smit B, Whitfield MC, Noakes MJ, Talbot WA, Garcia M, Gerson AR, Wolf BO. Avian thermoregulation in the heat: evaporative cooling capacity in an archetypal desert specialist, Burchell's sandgrouse (Pterocles burchelli). ACTA ACUST UNITED AC 2016; 219:2409. [PMID: 27489220 DOI: 10.1242/jeb.146563] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Noakes MJ, Wolf BO, McKechnie AE. Seasonal and geographical variation in heat tolerance and evaporative cooling capacity in a passerine bird. ACTA ACUST UNITED AC 2016; 219:859-69. [PMID: 26787477 DOI: 10.1242/jeb.132001] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/08/2016] [Indexed: 11/20/2022]
Abstract
Intraspecific variation in avian thermoregulatory responses to heat stress has received little attention, despite increasing evidence that endothermic animals show considerable physiological variation among populations. We investigated seasonal (summer versus winter) variation in heat tolerance and evaporative cooling in an Afrotropical ploceid passerine, the white-browed sparrow-weaver (Plocepasser mahali; ∼ 47 g) at three sites along a climatic gradient with more than 10 °C variation in mid-summer maximum air temperature (Ta). We measured resting metabolic rate (RMR) and total evaporative water loss (TEWL) using open flow-through respirometry, and core body temperature (Tb) using passive integrated transponder tags. Sparrow-weavers were exposed to a ramped profile of progressively higher Ta between 30 and 52 °C to elicit maximum evaporative cooling capacity (N=10 per site per season); the maximum Ta birds tolerated before the onset of severe hyperthermia (Tb ≈ 44 °C) was considered to be their hyperthermia threshold Ta (Ta,HT). Our data reveal significant seasonal acclimatisation of heat tolerance, with a desert population of sparrow-weavers reaching significantly higher Ta in summer (49.5 ± 1.4 °C, i.e. higher Ta,HT) than in winter (46.8 ± 0.9 °C), reflecting enhanced evaporative cooling during summer. Moreover, desert sparrow-weavers had significantly higher heat tolerance and evaporative cooling capacity during summer compared with populations from more mesic sites (Ta,HT=47.3 ± 1.5 and 47.6 ± 1.3 °C). A better understanding of the contributions of local adaptation versus phenotypic plasticity to intraspecific variation in avian heat tolerance and evaporative cooling capacity is needed for modelling species' responses to changing climates.
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Affiliation(s)
- Matthew J Noakes
- DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
| | - Blair O Wolf
- UNM Biology Department, University of New Mexico, MSC03-2020, Albuquerque, NM 87131-0001, USA
| | - Andrew E McKechnie
- DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
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McKechnie AE, Smit B, Whitfield MC, Noakes MJ, Talbot WA, Garcia M, Gerson AR, Wolf BO. Avian thermoregulation in the heat: evaporative cooling capacity in an archetypal desert specialist, Burchell's sandgrouse (Pterocles burchelli). J Exp Biol 2016; 219:2137-44. [DOI: 10.1242/jeb.139733] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 05/02/2016] [Indexed: 11/20/2022]
Abstract
Sandgrouse (Pterocliformes) are quintessential examples of avian adaptation to desert environments, but relatively little is known about the limits to their heat tolerance and evaporative cooling capacity. We predicted that evaporative cooling in Burchell's sandgrouse (Pterocles burchelli) is highly efficient and provides the basis for tolerance of very high air temperature (Ta). We measured body temperature (Tb), resting metabolic rate (RMR) and evaporative water loss (EWL) at Ta between 25 °C and ∼58 °C in birds exposed to successive increments in Ta. Normothermic Tb averaged 39.0 °C, lower than typical avian values. At Ta>34.5 °C, Tb increased linearly to a maximum of 43.6 °C at Ta=56 °C. The upper critical limit of thermoneutrality (Tuc) was Ta=43.8 °C, closely coinciding with the onset of panting and gular flutter. Above the Tuc, RMR increased 2.5-fold to 2.89 W at Ta=56 °C, a fractional increase far exceeding that of many other species under comparable conditions. Rates of EWL increased rapidly at Ta>42.9 °C to 7.84±0.90 g h−1 at Ta=56 °C, an 11-fold increase above minimal levels. Maximum evaporative cooling efficiency (ratio of evaporative heat loss to metabolic heat production) was 2.03, but could be as high as 2.70 if our assumption that the birds were metabolising lipids is incorrect. Thermoregulation at very high Ta in P. burchelli was characterised by large increases in RMR and EWL, and is much less efficient than in taxa such as columbids and caprimulgids.
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Affiliation(s)
- Andrew E. McKechnie
- DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Ben Smit
- Department of Zoology, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031, South Africa
| | - Maxine C. Whitfield
- DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Matthew J. Noakes
- DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - William A. Talbot
- UNM Biology Department, University of New Mexico, MSC03-2020, Albuquerque, NM 87131-0001, USA
| | - Mateo Garcia
- UNM Biology Department, University of New Mexico, MSC03-2020, Albuquerque, NM 87131-0001, USA
| | | | - Blair O. Wolf
- UNM Biology Department, University of New Mexico, MSC03-2020, Albuquerque, NM 87131-0001, USA
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Noakes MJ, Smit B, Wolf BO, McKechnie AE. Thermoregulation in African Green Pigeons (Treron calvus) and a re-analysis of insular effects on basal metabolic rate and heterothermy in columbid birds. J Comp Physiol B 2013; 183:969-82. [PMID: 23689380 DOI: 10.1007/s00360-013-0763-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/13/2013] [Accepted: 05/03/2013] [Indexed: 10/26/2022]
Abstract
Columbid birds represent a useful model taxon for examining adaptation in metabolic and thermal traits, including the effects of insularity. To test predictions concerning the role of insularity and low predation risk as factors selecting for the use of torpor, and the evolution of low basal metabolic rate in island species, we examined thermoregulation under laboratory and semi-natural conditions in a mainland species, the African Green Pigeon (Treron calvus). Under laboratory conditions, rest-phase body temperature (T b) was significantly and positively correlated with air temperature (T a) between 0 and 35 °C, and the relationship between resting metabolic rate (RMR) and T a differed from typical endothermic patterns. The minimum RMR, which we interpret as basal metabolic rate (BMR), was 0.825 ± 0.090 W. Green pigeons responded to food restriction by significantly decreasing rest-phase T b, but the reductions were small (at most ~5 °C below normothermic values), with a minimum T b of 33.1 °C recorded in a food-deprived bird. We found no evidence of the large reductions in T b and metabolic rate and the lethargic state characteristic of torpor. The absence of torpor in T. calvus lends support to the idea that species restricted to islands that are free of predators are more likely to use torpor than mainland species that face the risk of predation during the rest-phase. We also analysed interspecific variation in columbid BMR in a phylogenetically informed framework and verified the conclusions of an earlier study which found that BMR is significantly lower in island species compared to those that occur on mainlands.
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Affiliation(s)
- Matthew J Noakes
- Department of Zoology and Entomology, DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, University of Pretoria, Pretoria, 0002, South Africa
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Abstract
A method of assessing and comparing double contrast barium meals has been devised. The use of the linear analogue scale has been found to be a consistent method of recording and measuring radiological impression of mucosal coating and gaseous distension. By this means the effectiveness of various currently available barium and gas preparations has been assessed in 125 patients. Appreciable differences in mucosal coating achieved by different barium preparations were detected. Satisfactory gaseous distension of the stomach and duodenum was produced in the majority of patients by all of the methods tested, and the following measurements are suggested as an index of good distension: gastric fundus 10 cm, gastric midbody 7 cm, duodenal loop 4 cm. The relationships between mucosal coating, gaseous distension and areae gastricae have been shown to be tenuous. It is suggested that the methods we have used are very suitable for repetition in other centres for the comparison of any of the many barium and gas-producing agents which continue to come on to the market.
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Abstract
A case is described of the death of a young female patient following the administration of a salt emetic after a relatively minor overdose of a proprietary analgesic containing aspirin. It is suggested that death occurred as a direct consequence of the salt ingestion and that the dangers of this method of inducing emesis should be more widely appreciated.
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