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Tremblay F, Choy ES, Fifield DA, Tattersall GJ, Vézina F, O'Connor R, Love OP, Gilchrist GH, Elliott KH. Dealing with the heat: Assessing heat stress in an Arctic seabird using 3D-printed thermal models. Comp Biochem Physiol A Mol Integr Physiol 2025:111880. [PMID: 40393560 DOI: 10.1016/j.cbpa.2025.111880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2025] [Revised: 05/06/2025] [Accepted: 05/12/2025] [Indexed: 05/22/2025]
Abstract
The Arctic is warming at four times the global average rate and most studies have focused on the indirect (e.g., changes in food web) rather than the direct effects of climate change. However, as Arctic animals often have low capacity to dissipate heat, the direct effect of warming could impact them significantly (heat stress). To study heat stress, biophysical models have been used in many species to estimate operative temperature (Te, integrated temperature of the thermal environment experienced by an individual). Here, we developed biophysical models of an Arctic seabird, the thick-billed murre (Uria lomvia). We demonstrated that 3D-printed painted models perform similarly to the more traditionally used feather-covered models. We deployed our models on Coats Island, Nunavut, Canada to study heat stress, which occurs in murres when operative temperature is above 21.2 °C (the temperature at which evaporative water loss (EWL) rates increase to maintain a constant body temperatures). Murre operative temperatures ranged from 5.5 °C to 46.5 °C despite ambient temperatures never exceeding 24.7 °C (range: 3.4-24.7 °C), and murres experienced heat stress on 61 % of the days during the breeding season (range: 24-85 %). Using known equations of EWL as a function of temperature, we estimated that murres lost 3.79 % to 4.61 % of their body mass in water daily. Our study confirms the physiological challenges faced by Arctic seabirds during the breeding season, while also demonstrating the value of biophysical models as non-invasive tools to study the effects of heat stress on seabirds.
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Affiliation(s)
- Fred Tremblay
- Department of Natural Resource Sciences, McGill University, Canada.
| | - Emily S Choy
- Department of Biology, McMaster University, Canada
| | - David A Fifield
- Wildlife Research Division, Environment and Climate Change Canada, Canada
| | | | - François Vézina
- Départment de biologie, chimie et géographie, Université du Québec à Rimouski, Canada
| | - Ryan O'Connor
- Départment de biologie, chimie et géographie, Université du Québec à Rimouski, Canada
| | - Oliver P Love
- Department of Integrative Biology, University of Windsor, Canada
| | - Grant H Gilchrist
- Wildlife Research Division, Environment and Climate Change Canada, Canada
| | - Kyle H Elliott
- Department of Natural Resource Sciences, McGill University, Canada
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2
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Tabh JKR, Persson E, Correia M, Cuív CÓ, Thoral E, Nord A. Limited evidence that body size shrinking and shape-shifting alleviate thermoregulatory pressures in a warmer world. Commun Biol 2025; 8:707. [PMID: 40335683 PMCID: PMC12059039 DOI: 10.1038/s42003-025-08131-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Accepted: 04/25/2025] [Indexed: 05/09/2025] Open
Abstract
Amassing evidence indicates that vertebrates across the globe are shrinking and changing shape concurrent with rising temperatures. Ecogeographical theories assert that these changes should provide thermoregulatory benefits by easing heat dissipation, however, thermophysical models underpinning such theories are highly simplified and lack empirical validation. Using data from three temperature-manipulation experiments, we quantified the contributions of body size and appendage lengths toward thermoregulatory performance in Japanese quail, while simultaneously querying neutral plasticity as an alternative driver of avian shape-shifts. In the cold, body mass and leg length (here, tarsus length) influenced energy costs of warming, but only among juveniles. In the warmth, smaller body sizes, longer legs and longer bills independently reduced energy and water costs of cooling across ages, but whole-body phenotypes necessary to provide even moderate thermoregulatory benefits were rare (2.5%) and required large departures from allometry. Last, rearing in the warmth reduced body sizes and increased appendage lengths comparable to recent changes observed in nature, but emergent morphologies provided no clear thermoregulatory benefit. Our findings question whether shrinking and shape-shifting are indeed easing thermoregulation in birds or reflect selection for such. Neutral plasticity, or relaxed selection against small body size in juveniles, may better explain recent avian shape-shifting.
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Affiliation(s)
| | - Elin Persson
- Department of Biology, Lund University, Lund, Sweden
| | - Maria Correia
- Department of Biology, Lund University, Lund, Sweden
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Ciarán Ó Cuív
- Department of Biology, Lund University, Lund, Sweden
- Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Elisa Thoral
- Department of Biology, Lund University, Lund, Sweden
- Département de Biologie, LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université, La Rochelle, France
| | - Andreas Nord
- Department of Biology, Lund University, Lund, Sweden
- Swedish Centre for Impacts of Climate Extremes (climes), Lund University, Lund, Sweden
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3
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Casagrande S, Dell'Omo G. Linking warmer nest temperatures to reduced body size in seabird nestlings: possible mitochondrial bioenergetic and proteomic mechanisms. J Exp Biol 2025; 228:jeb249880. [PMID: 39886833 DOI: 10.1242/jeb.249880] [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: 06/10/2024] [Accepted: 01/16/2025] [Indexed: 02/01/2025]
Abstract
Rapid reduction of body size in populations responding to global warming suggests the involvement of temperature-dependent physiological adjustments during growth, such as mitochondrial alterations in the efficiency of producing metabolic energy, a process that is poorly explored, especially in endotherms. Here, we examined the mitochondrial metabolism and proteomic profile of red blood cells in relation to body size and cellular energetics in nestling shearwaters (Calonectris diomedea) developing at different natural temperatures. We found that nestlings of warmer nests had lighter bodies and smaller beaks at fledging. Despite the fact that there was no effect of environmental temperature on cellular metabolic rate, mitochondria had a higher inefficiency in coupling metabolism to allocable energy production, as evidenced by bioenergetic and proteomic analyses. Mitochondrial inefficiency was positively related to cellular stress represented by heat shock proteins, antioxidant enzymes and markers of mitochondrial stress. The observed temperature-related mitochondrial inefficiency was associated with reduced beak size and body mass, and was linked to a downregulation of cellular growth factors and growth promoters determining body size. By analyzing the links between environmental temperature, mitochondrial inefficiency and body size, we discuss the physiological alterations that free-living birds, and probably other endotherms, need to trigger to cope with a warming world.
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Affiliation(s)
- Stefania Casagrande
- Evolutionary Physiology Research Group, Max-Planck-Institut für Biologische Intelligenz 82319, Seewiesen, Germany
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4
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Benham PM, Beckman EJ. Integrating Spatial Analyses of Genomic and Physiological Data to Understand Avian Responses to Environmental Change. Integr Comp Biol 2024; 64:1792-1810. [PMID: 38830811 DOI: 10.1093/icb/icae059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 05/03/2024] [Accepted: 05/20/2024] [Indexed: 06/05/2024] Open
Abstract
Projected rates of climate change over the next century are expected to force species to shift ranges, adapt, or acclimate to evade extinction. Predicting which of these scenarios may be most likely is a central challenge for conserving biodiversity in the immediate future. Modeling frameworks that take advantage of intraspecific variation across environmental gradients can be particularly important for meeting this challenge. While these space-for-time approaches are essential for climatic and genomic modeling approaches, mechanistic models that incorporate ecological physiology data into assessing species vulnerabilities rarely include intraspecific variation. A major reason for this gap is the general lack of empirical data on intraspecific geographic variation in avian physiological traits. In this review, we outline the evidence for and processes shaping geographic variation in avian traits. We use the example of evaporative water loss to underscore the lack of research on geographic variation, even in traits central to cooling costs in birds. We next demonstrate how shifting the focus of avian physiological research to intraspecific variation can facilitate greater integration with emerging genomics approaches. Finally, we outline important next steps for an integrative approach to advance understanding of avian physiological adaptation within species. Addressing the knowledge gaps outlined in this review will contribute to an improved predictive framework that synthesizes environmental, morphological, physiological, and genomic data to assess species specific vulnerabilities to a warming planet.
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Affiliation(s)
- Phred M Benham
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Elizabeth J Beckman
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA 94720, USA
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5
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Colominas-Ciuró R, Kowalczewska A, Jefimow M, Wojciechowski MS. Temperature and water availability induce chronic stress responses in zebra finches (Taeniopygia guttata). J Exp Biol 2024; 227:jeb247743. [PMID: 39445475 DOI: 10.1242/jeb.247743] [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: 03/15/2024] [Accepted: 10/08/2024] [Indexed: 10/25/2024]
Abstract
Animals initiate physiological mechanisms to re-establish homeostasis following environmental stress. To understand how bird physiology responds to abiotic stress, we quantified changes in haematological markers of chronic stress response and body condition of male zebra finches (Taeniopygia guttata) acclimated for 18 weeks to hot and cool temperatures (daytime temperature: 40°C and 23°C) with water available ad libitum or restricted during half of the active phase. Ambient temperature induced greater chronic stress than restricted water availability. While cool compared with hot temperatures induced higher numbers of heterophils and heterophil to lymphocyte (H:L) ratios and reduced total leucocyte count, water restriction decreased the number of lymphocytes compared with water ad libitum. Body condition correlated with haematological parameters showing that birds with better condition had greater capacity to face environmental stress. Therefore, prolonged exposure to cool periods may result in chronic stress in zebra finches, especially if body condition is weakened.
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Affiliation(s)
- Roger Colominas-Ciuró
- Department of Vertebrate Zoology and Ecology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, 87-100 Toruń, Poland
| | - Anna Kowalczewska
- Department of Vertebrate Zoology and Ecology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, 87-100 Toruń, Poland
| | - Małgorzata Jefimow
- Department of Animal Physiology and Neurobiology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, 87-100 Toruń, Poland
| | - Michał S Wojciechowski
- Department of Vertebrate Zoology and Ecology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, 87-100 Toruń, Poland
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6
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Coulson B, Freeman MT, Wessels J, McKechnie AE. Non-evaporative heat dissipation across the beaks and casques of large forest hornbills. J Therm Biol 2024; 125:103993. [PMID: 39433002 DOI: 10.1016/j.jtherbio.2024.103993] [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: 07/14/2024] [Revised: 09/10/2024] [Accepted: 09/26/2024] [Indexed: 10/23/2024]
Abstract
Heat loss across the beak is an important thermoregulatory mechanism among birds, particularly in large-beaked taxa such as toucans (Ramphastidae) and hornbills (Bucerotidae). The number of species investigated remains limited, as does our understanding of how the functional significance of this pathway varies with environmental variables such as humidity, with little previous research on species inhabiting humid environments. We used infrared thermography to test the hypothesis that large (600-1300 g) Afrotropical forest hornbills use their beaks and casques as thermal radiators. We collected data over air temperatures (Tair) of 15-34 °C for wild-caught trumpeter hornbills (Bycanistes bucinator) and captive-bred silvery-cheeked hornbills (Bycanistes brevis) and black-casqued hornbills (Ceratogymna atrata). Surface temperatures of the beaks and casques (Tbeak) tracked Tair below 24-25 °C, but at higher Tair, the Tbeak - Tair gradient increased to maximum values of 10-12 °C. Maximum rates of beak heat loss were 2.5-3.8 W, equivalent to 31-83 % of estimated resting metabolic heat production. Facial skin showed also evidence for active regulation of heat loss. We also analysed the scaling of the inflection Tair above which the Tbeak - Tair gradient increases (Tinflection) by combining our data with published and three unpublished values. We found that Tinflection decreases with increasing body mass (Mb), with the relationship best described by the linear regression model Tinflection = -9.134log10Mb + 50.83, with Mb in g.
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Affiliation(s)
- Bianca Coulson
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, P.O. Box 754, Pretoria, 0001, South Africa; Department of Zoology and Entomology, University of Pretoria, Hatfield, Private Bag X20, Pretoria 0028, South Africa
| | - Marc T Freeman
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, P.O. Box 754, Pretoria, 0001, South Africa; Department of Zoology and Entomology, University of Pretoria, Hatfield, Private Bag X20, Pretoria 0028, South Africa
| | - Juanita Wessels
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, P.O. Box 754, Pretoria, 0001, South Africa; Department of Zoology and Entomology, University of Pretoria, Hatfield, Private Bag X20, Pretoria 0028, South Africa
| | - Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, P.O. Box 754, Pretoria, 0001, South Africa; Department of Zoology and Entomology, University of Pretoria, Hatfield, Private Bag X20, Pretoria 0028, South Africa.
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7
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Wu NC, Alton L, Bovo RP, Carey N, Currie SE, Lighton JRB, McKechnie AE, Pottier P, Rossi G, White CR, Levesque DL. Reporting guidelines for terrestrial respirometry: Building openness, transparency of metabolic rate and evaporative water loss data. Comp Biochem Physiol A Mol Integr Physiol 2024; 296:111688. [PMID: 38944270 DOI: 10.1016/j.cbpa.2024.111688] [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: 02/19/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/01/2024]
Abstract
Respirometry is an important tool for understanding whole-animal energy and water balance in relation to the environment. Consequently, the growing number of studies using respirometry over the last decade warrants reliable reporting and data sharing for effective dissemination and research synthesis. We provide a checklist guideline on five key sections to facilitate the transparency, reproducibility, and replicability of respirometry studies: 1) materials, set up, plumbing, 2) subject conditions/maintenance, 3) measurement conditions, 4) data processing, and 5) data reporting and statistics, each with explanations and example studies. Transparency in reporting and data availability has benefits on multiple fronts. Authors can use this checklist to design and report on their study, and reviewers and editors can use the checklist to assess the reporting quality of the manuscripts they review. Improved standards for reporting will enhance the value of primary studies and will greatly facilitate the ability to carry out higher quality research syntheses to address ecological and evolutionary theories.
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Affiliation(s)
- Nicholas C Wu
- Hawkesbury Institute for the Environment, Western Sydney University, New South Wales 2753, Australia.
| | - Lesley Alton
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia. https://twitter.com/lesley_alton
| | - Rafael P Bovo
- Department of Evolution, Ecology, and Organismal Biology, University of California Riverside, Riverside, CA, United States. https://twitter.com/bovo_rp
| | - Nicholas Carey
- Marine Directorate for the Scottish Government, Aberdeen, United Kingdom
| | - Shannon E Currie
- Institute for Cell and Systems Biology, University of Hamburg, Martin-Luther-King Plz 3, 20146 Hamburg, Germany; School of Biosciences, University of Melbourne, Victoria, Australia. https://twitter.com/batsinthbelfry
| | - John R B Lighton
- Sable Systems International, North Las Vegas, NV, United States. https://twitter.com/SableSys
| | - Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, South Africa; DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, South Africa
| | - Patrice Pottier
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia; Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia. https://twitter.com/PatriceEcoEvo
| | - Giulia Rossi
- Department of Biology, McMaster University, Hamilton, Ontario, Canada. https://twitter.com/giuliasrossi
| | - Craig R White
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Danielle L Levesque
- School of Biology and Ecology, University of Maine, Orono, ME, United States. https://twitter.com/dl_levesque
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8
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McKechnie AE, Freeman MT, Kemp R, Wolter K, Naidoo V. Effects of lead on avian thermoregulation in the heat: An experimental test with pied crows (Corvus albus). ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2024; 110:104519. [PMID: 39059727 DOI: 10.1016/j.etap.2024.104519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 07/20/2024] [Accepted: 07/23/2024] [Indexed: 07/28/2024]
Abstract
Many of the negative physiological effects of lead involve the hypothalamus, but the possibility that thermoregulation is affected has received little attention. We tested the hypothesis that lead exposure reduces avian thermoregulatory performance under hot conditions in pied crows (Corvus albus) experimentally exposed to lead in their diet. Crows in our high lead treatment (blood [Pb] = 87.3 ± 44.7 μg dL-1) showed significantly higher air temperature (Tair) inflections for evaporative water loss (EWL) and resting metabolic rate (RMR) compared to control (6.4 ± 1.8 μg dL-1) or intermediate (53.9 ± 23.7 μg dL-1) lead groups, which did not differ. EWL, RMR and body temperature (Tb) all increased more rapidly at Tair > Tb in the high lead treatment. In contrast, neither maximum Tair tolerated by the crows nor maximum Tb varied with treatment. Our data reveal that water and energy balance during hot weather is affected by lead exposure.
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Affiliation(s)
- Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, South Africa; DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, South Africa.
| | - Marc T Freeman
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, South Africa; DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, South Africa
| | - Ryno Kemp
- Vulture Programme (VulPro), Plot 121, Rietfontein 0216, South Africa
| | - Kerri Wolter
- Vulture Programme (VulPro), Plot 121, Rietfontein 0216, South Africa
| | - Vinny Naidoo
- Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, South Africa
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9
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Welman S, Breit AM, Levesque DL, Nowack J. The upper limit of thermoneutrality is not indicative of thermotolerance in bats. J Therm Biol 2024; 124:103933. [PMID: 39208468 DOI: 10.1016/j.jtherbio.2024.103933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 07/14/2024] [Accepted: 07/14/2024] [Indexed: 09/04/2024]
Abstract
To assess the vulnerability of birds and mammals to climate change recent studies have used the upper critical limit of thermoneutrality (TUC) as an indicator of thermal tolerance. But, the association between TUC and thermal tolerance is not straightforward and most studies describe TUC based solely on a deviation in metabolism from basal levels, without also considering the onset of evaporative cooling. It was argued recently that certain torpor-using bat species who survived prolonged exposure to high ambient temperatures (i.e. high thermal tolerance) experienced during extreme heat events did so by entering torpor and using facultative heterothermy to thermoconform and save on body water. Assuming that TUC is indicative of thermal tolerance, we expect TUC in torpor-using species to be higher than that of species which are obligate homeotherms, albeit that this distinction is based on confirmation of torpor use at low temperatures. To test this prediction, we performed a phylogenetically informed comparison of bat species known to use torpor (n = 48) and homeothermic (n = 16) bat species using published thermoregulatory datasets to compare the lower critical limit of thermoneutrality (TLC) and TUC in relation to body temperature. The influence of diet, biogeographical region, body mass and basal metabolic rate (BMR) was also considered. Body mass had a positive relationship with BMR, an inverse relationship with TLC and no relationship with TUC. Normothermic body temperature scaled positively with BMR, TLC and TUC. There was no relationship between diet or region and BMR, but both influenced thermal limits. Torpor-using bats had lower body mass and body temperatures than homeothermic bats, but there was no difference in BMR, TLC and TUC between them. Exceptional examples of physiological flexibility were observed in 34 torpor-using species and eight homeothermic species, which included 15 species of bats maintaining BMR-level metabolism at ambient temperatures as high as 40 °C (and corresponding body temperatures ∼39.2 °C). However, we argue that TUC based on metabolism alone is not an appropriate indicator of thermal tolerance as it disregards differences in the ability of animals to tolerate higher levels of hyperthermia, importance of hydration status and capacity for evaporative cooling. Also, the variability in TUC based on diet challenges the idea of evolutionary conservatism and warrants further consideration.
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Affiliation(s)
- Shaun Welman
- Department of Biological Sciences, University of Cape Town, Cape Town, 7701, South Africa; Department of Zoology, Nelson Mandela University, Gqeberha, 6031, South Africa.
| | - Ana M Breit
- School of Biology and Ecology, University of Maine, 04469 Orono, ME, USA; School of Life Sciences, University of Nevada Las Vegas, 89154, Las Vegas, NV, USA
| | | | - Julia Nowack
- School of Biological and Environmental Sciences, Liverpool John Moores University, L3 3AF, Liverpool, UK
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10
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Blumstein D, MacManes M. The multi-tissue gene expression and physiological responses of water deprived Peromyscus eremicus. BMC Genomics 2024; 25:770. [PMID: 39118009 PMCID: PMC11308687 DOI: 10.1186/s12864-024-10629-z] [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: 03/06/2024] [Accepted: 07/17/2024] [Indexed: 08/10/2024] Open
Abstract
The harsh and dry conditions of desert environments have resulted in genomic adaptations, allowing for desert organisms to withstand prolonged drought, extreme temperatures, and limited food resources. Here, we present a comprehensive exploration of gene expression across five tissues (kidney, liver, lung, gastrointestinal tract, and hypothalamus) and 19 phenotypic measurements to explore the whole-organism physiological and genomic response to water deprivation in the desert-adapted cactus mouse (Peromyscus eremicus). The findings encompass the identification of differentially expressed genes and correlative analysis between phenotypes and gene expression patterns across multiple tissues. Specifically, we found robust activation of the vasopressin renin-angiotensin-aldosterone system (RAAS) pathways, whose primary function is to manage water and solute balance. Animals reduced food intake during water deprivation, and upregulation of PCK1 highlights the adaptive response to reduced oral intake via its actions aimed at maintained serum glucose levels. Even with such responses to maintain water balance, hemoconcentration still occurred, prompting a protective downregulation of genes responsible for the production of clotting factors while simultaneously enhancing angiogenesis which is thought to maintain tissue perfusion. In this study, we elucidate the complex mechanisms involved in water balance in the desert-adapted cactus mouse, P. eremicus. By prioritizing a comprehensive analysis of whole-organism physiology and multi-tissue gene expression in a simulated desert environment, we describe the complex response of regulatory processes.
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Affiliation(s)
- Danielle Blumstein
- Biomedical Sciences Department, University of New Hampshire, Molecular, Cellular, Durham, NH, DMB, 03824, USA.
| | - Matthew MacManes
- Biomedical Sciences Department, University of New Hampshire, Molecular, Cellular, Durham, NH, DMB, 03824, USA
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11
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Voges JJ, Freeman MT, Wolf BO, McKechnie AE. Functional role of metabolic suppression in avian thermoregulation in the heat. J Therm Biol 2024; 123:103924. [PMID: 39089117 DOI: 10.1016/j.jtherbio.2024.103924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 07/10/2024] [Accepted: 07/10/2024] [Indexed: 08/03/2024]
Abstract
Hypometabolism arising from active metabolic suppression occurs in several contexts among endotherms, particularly during heterothermic states such as torpor. However, observed Q10 ≈ 1 for avian resting metabolic rate within the thermoneutral zone, values far below the Q10 = 2-3 expected on the basis of Arrhenius effects, suggests hypometabolism also plays a role in birds' thermoregulation at environmental temperatures approaching or exceeding normothermic body temperature (Tb). We evaluated the occurrence of hypometabolism during heat exposure among birds by re-analysing literature data to quantify changes in Tb and resting metabolic rate (RMR) near the upper boundary of the thermoneutral zone, at air temperatures (Tair) between the inflection above which Tb increases above normothermic levels (Tb.inf) and the upper critical limit of thermoneutrality (Tuc). Among the ∼55 % of species in which Tuc - Tb.inf > 0, Q10 < 2-3 occurred in nine of 10 orders for which suitable data exist, indicating that hypometabolism during heat exposure is widespread across the avian phylogeny. Values of Q10 < 2-3 were not restricted to small body mass, as previously proposed. Our findings support the idea that metabolic suppression reduces avian metabolic heat production and hence evaporative cooling requirements during heat exposure, with reductions of 20-30 % in RMR in some species. Moreover, these findings add to evidence that hypometabolism is an important component of heat tolerance among endotherms such as birds and tropical arboreal mammals.
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Affiliation(s)
- Jochen J Voges
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria, 0001, South Africa; DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, 0028, South Africa
| | - Marc T Freeman
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria, 0001, South Africa; DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, 0028, South Africa
| | - Blair O Wolf
- UNM Biology Department, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria, 0001, South Africa; DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, 0028, South Africa.
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12
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Czenze ZJ, Noakes MJ, Wojciechowski MS. Bat thermoregulation in the heat: seasonal variation in evaporative cooling capacities in four species of European bats. J Therm Biol 2024; 123:103911. [PMID: 38991263 DOI: 10.1016/j.jtherbio.2024.103911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 06/07/2024] [Accepted: 06/24/2024] [Indexed: 07/13/2024]
Abstract
Phenotypic flexibility is an important source of physiological variation in endotherms and plays an integral role in species' response to rapid environmental changes. Studies of phenotypic flexibility have focused on winter acclimatization and cold endurance, and there are fewer data on summer acclimatization and adjustments in heat dissipation capacity, especially in Temperate-Zone species. We used indirect calorimetry and thermometry to test if thermoregulation at high air temperatures (Ta) varies between spring and summer in four species of European vespertilionid bats: Nyctalus noctula, Pipistrellus nathusii, P. pygmaeus, and P. pipistrellus. We measured subcutaneous body temperature (Tsub), evaporative water loss, and resting metabolic rate while exposing bats to a stepped profile of increasing Ta, from 28 °C-48 °C. We predicted that during summer, bats increase heat tolerance and evaporative cooling capacity, to better tolerate hotter Tas. In contrast, we found lower maximum ratios of evaporative heat loss (EHL) to metabolic heat production (MHP) during summer, but no seasonal differences in maximum Ta tolerated or Tsub. The main cause of this seasonal difference in maximum EHL/MHP seems to be from bats increasing EWL more gradually with increasing Ta in summer than spring, particularly in the smaller Pipistrellus species. Therefore, this seasonal variation in heat-dissipation strategies may reflect enhanced water conservation during summer to avoid dehydration, as bats are confined to roosts for longer and hotter days compared to spring.
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Affiliation(s)
- Zenon J Czenze
- Centre for Behavioural and Physiological Ecology, University of New England, Armidale, NSW, 2351, Australia.
| | - Matthew J Noakes
- School of Animal, Plant, and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Michał S Wojciechowski
- Department of Vertebrate Zoology and Ecology, Nicolaus Copernicus University, Toruń, Poland
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13
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Nord A, Persson E, Tabh JKR, Thoral E. Shrinking body size may not provide meaningful thermoregulatory benefits in a warmer world. Nat Ecol Evol 2024; 8:387-389. [PMID: 38225428 DOI: 10.1038/s41559-023-02307-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 12/13/2023] [Indexed: 01/17/2024]
Affiliation(s)
- Andreas Nord
- Lund University, Department of Biology, Section for Evolutionary Ecology, Lund, Sweden.
| | - Elin Persson
- Lund University, Department of Biology, Section for Evolutionary Ecology, Lund, Sweden
| | - Joshua K R Tabh
- Lund University, Department of Biology, Section for Evolutionary Ecology, Lund, Sweden
| | - Elisa Thoral
- Lund University, Department of Biology, Section for Evolutionary Ecology, Lund, Sweden
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14
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Blumstein DM, MacManes MD. When the tap runs dry: The multi-tissue gene expression and physiological responses of water deprived Peromyscus eremicus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.22.576658. [PMID: 38328088 PMCID: PMC10849551 DOI: 10.1101/2024.01.22.576658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
The harsh and dry conditions of desert environments have resulted in genomic adaptations, allowing for desert organisms to withstand prolonged drought, extreme temperatures, and limited food resources. Here, we present a comprehensive exploration of gene expression across five tissues (kidney, liver, lung, gastrointestinal tract, and hypothalamus) and 19 phenotypic measurements to explore the whole-organism physiological and genomic response to water deprivation in the desert-adapted cactus mouse (Peromyscus eremicus). The findings encompass the identification of differentially expressed genes and correlative analysis between phenotypes and gene expression patterns across multiple tissues. Specifically, we found robust activation of the vasopressin renin-angiotensin-aldosterone system (RAAS) pathways, whose primary function is to manage water and solute balance. Animals reduce food intake during water deprivation, and upregulation of PCK1 highlights the adaptive response to reduced oral intake via its actions aimed at maintained serum glucose levels. Even with such responses to maintain water balance, hemoconcentration still occurred, prompting a protective downregulation of genes responsible for the production of clotting factors while simultaneously enhancing angiogenesis which is thought to maintains tissue perfusion. In this study, we elucidate the complex mechanisms involved in water balance in the desert-adapted cactus mouse, P. eremicus. By prioritizing a comprehensive analysis of whole-organism physiology and multi-tissue gene expression in a simulated desert environment, we describe the complex and successful response of regulatory processes.
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Affiliation(s)
- Danielle M Blumstein
- University of New Hampshire, Molecular, Cellular, and Biomedical Sciences Department, Durham, NH 03824
| | - Matthew D MacManes
- University of New Hampshire, Molecular, Cellular, and Biomedical Sciences Department, Durham, NH 03824
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15
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Ding C, Newbold T, Ameca EI. Assessing the global vulnerability of dryland birds to heatwaves. GLOBAL CHANGE BIOLOGY 2024; 30:e17136. [PMID: 38273501 DOI: 10.1111/gcb.17136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 12/11/2023] [Accepted: 12/19/2023] [Indexed: 01/27/2024]
Abstract
As global average surface temperature increases, extreme climatic events such as heatwaves are becoming more frequent and intense, which can drive biodiversity responses such as rapid population declines and/or shifts in species distributions and even local extirpations. However, the impacts of extreme climatic events are largely ignored in conservation plans. Birds are known to be susceptible to heatwaves, especially in dryland ecosystems. Understanding which birds are most vulnerable to heatwaves, and where these birds occur, can offer a scientific basis for adaptive management and conservation. We assessed the relative vulnerability of 1196 dryland bird species to heatwaves using a trait-based approach. Among them, 888 bird species are estimated to be vulnerable to heatwaves (170 highly vulnerable, eight extremely vulnerable), of which ~91% are currently considered non-threatened by the IUCN, which suggests that many species will likely become newly threatened with intensifying climate change. We identified the top three hotspot areas of heatwave-vulnerable species in Australia (208 species), Southern Africa (125 species) and Eastern Africa (99 species). Populations of vulnerable species recorded in the Living Planet Database were found to be declining significantly faster than those of non-vulnerable species (p = .048) after heatwaves occurred. In contrast, no significant difference in population trends between vulnerable and non-vulnerable species was detected when no heatwave occurred (p = .34). This suggests that our vulnerability framework correctly identified vulnerable species and that heatwaves are already impacting the population trends of these species. Our findings will help prioritize heatwave-vulnerable birds in dryland ecosystems in risk mitigation and adaptation management as the frequency of heatwaves accelerates in the coming decades.
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Affiliation(s)
- Chenchen Ding
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
- Centre for Biodiversity and Environment Research, Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Tim Newbold
- Centre for Biodiversity and Environment Research, Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Eric I Ameca
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
- Climate Change Specialist Group, Species Survival Commission, International Union for Conservation of Nature, Gland, Switzerland
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16
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McKechnie AE, Freeman MT, Brigham RM. Avian Heterothermy: A Review of Patterns and Processes. Integr Comp Biol 2023; 63:1028-1038. [PMID: 37156524 DOI: 10.1093/icb/icad029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 05/02/2023] [Accepted: 05/05/2023] [Indexed: 05/10/2023] Open
Abstract
Many birds reduce rest-phase energy demands through heterothermy, physiological responses involving facultative, reversible reductions in metabolic rate and body temperature (Tb). Here, we review the phylogenetic distribution and ecological contexts of avian heterothermy. Heterothermy has been reported in 140 species representing 15 orders and 39 families. Recent work supports the view that deep heterothermy is most pronounced in phylogenetically older taxa whereas heterothermy in passerines and other recently diverged taxa is shallower and confined to minimum Tb > 20°C. The reasons why deep heterothermy is absent in passerines remain unclear; we speculate an evolutionary trade-off may exist between the capacity to achieve low heterothermic Tb and the tolerance of hyperthermic Tb. Inter- and intraspecific variation in heterothermy is correlated with factors including foraging ecology (e.g., territoriality and defense of food resources among hummingbirds), food availability and foraging opportunities (e.g., lunar phase predicts torpor use in caprimulgids), and predation risk. Heterothermy also plays a major role before and during migration. Emerging questions include the magnitude of energy savings associated with heterothermy among free-ranging birds, the role phylogenetic variation in the capacity for heterothermy has played in evolutionary radiations into extreme habitats, and how the capacity for heterothermy affects avian vulnerability to rapid anthropogenic climate change.
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Affiliation(s)
- Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria 0001, South Africa
- DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield 0028, South Africa
| | - Marc T Freeman
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria 0001, South Africa
- DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield 0028, South Africa
| | - R Mark Brigham
- Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada
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17
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Lewden A, Bishop CM, Askew GN. How birds dissipate heat before, during and after flight. J R Soc Interface 2023; 20:20230442. [PMID: 38086401 PMCID: PMC10715914 DOI: 10.1098/rsif.2023.0442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 11/17/2023] [Indexed: 12/18/2023] Open
Abstract
Animal flight uses metabolic energy at a higher rate than any other mode of locomotion. A relatively small proportion of the metabolic energy is converted into mechanical power; the remainder is given off as heat. Effective heat dissipation is necessary to avoid hyperthermia. In this study, we measured surface temperatures in lovebirds (Agapornis personatus) using infrared thermography and used heat transfer modelling to calculate heat dissipation by convection, radiation and conduction, before, during and after flight. The total non-evaporative rate of heat dissipation in flying birds was 12× higher than before flight and 19× higher than after flight. During flight, heat was largely dissipated by forced convection, via the exposed ventral wing areas, resulting in lower surface temperatures compared with birds at rest. When perched, both before and after exercise, the head and trunk were the main areas involved in dissipating heat. The surface temperature of the legs increased with flight duration and remained high on landing, suggesting that there was an increase in the flow of warmer blood to this region during and after flight. The methodology developed in this study to investigate how birds thermoregulate during flight could be used in future studies to assess the impact of climate change on the behavioural ecology of birds, particularly those species undertaking migratory flights.
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Affiliation(s)
- Agnès Lewden
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Univ Brest, CNRS, IRD, Ifremer, LEMAR, IUEM, F-29280 Plouzané, France
| | | | - Graham N. Askew
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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18
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Pessato A, Udino E, McKechnie AE, Bennett ATD, Mariette MM. Thermal acclimatisation to heatwave conditions is rapid but sex-specific in wild zebra finches. Sci Rep 2023; 13:18297. [PMID: 37880274 PMCID: PMC10600105 DOI: 10.1038/s41598-023-45291-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 10/18/2023] [Indexed: 10/27/2023] Open
Abstract
Under climate change, increasing air temperature average and variability pose substantial thermal challenges to animals. While plasticity in thermoregulatory traits could potentially attenuate this impact, whether thermal acclimatisation can occur quickly enough to track weather variability in hot climates is unknown in any endotherm, and sex differences have never been tested. We investigated acclimatisation responsiveness of male and female wild zebra finches to short-term (< 2 weeks) summer temperature fluctuations in the Australian desert. Hotter weather before respirometry trials triggered a typical acclimatisation response (especially at chamber temperature Tchamb ≥ 40). However, acclimatisation occurred remarkably rapidly: metabolic rate responded within just one day, while body temperature (Tb) and evaporative cooling capacity (EHL/MHP) were best predicted by weather on the trial day; whereas evaporative water loss responded more slowly (1 week). Nonetheless, rapid acclimatisation only occurred in males, and females had higher Tb and lower EHL/MHP than males, potentially increasing hyperthermia risk. Furthermore, acclimatisation did not translate into greater acute heat tolerance (i.e. ability to tolerate Tchamb = 46 °C). Our results therefore reveal surprisingly rapid acclimatisation and even anticipatory adjustments to heat. However, with no changes in acute heat tolerance, and in females, phenotypic flexibility may provide only limited buffering against the detrimental impact of heatwaves.
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Affiliation(s)
- Anaïs Pessato
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong 3216, VIC, Australia
| | - Eve Udino
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong 3216, VIC, Australia
| | - Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria, 0001, South Africa
- DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0001, South Africa
| | - Andrew T D Bennett
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong 3216, VIC, Australia
- One Health Research Group, Melbourne Veterinary School, Faculty of Science, University of Melbourne, Werribee, VIC, 3030, Australia
| | - Mylene M Mariette
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong 3216, VIC, Australia.
- Doñana Biological Station EBD-CSIC, 41092, Seville, Spain.
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19
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Sentís M, Pacioni C, De Cuyper A, Janssens GP, Lens L, Strubbe D. Biophysical models accurately characterize the thermal energetics of a small invasive passerine bird. iScience 2023; 26:107743. [PMID: 37720095 PMCID: PMC10504485 DOI: 10.1016/j.isci.2023.107743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 07/10/2023] [Accepted: 08/24/2023] [Indexed: 09/19/2023] Open
Abstract
Effective management of invasive species requires accurate predictions of their invasion potential in different environments. By considering species' physiological tolerances and requirements, biophysical mechanistic models can potentially deliver accurate predictions of where introduced species are likely to establish. Here, we evaluate biophysical model predictions of energy use by comparing them to experimentally obtained energy expenditure (EE) and thermoneutral zones (TNZs) for the common waxbill Estrilda astrild, a small-bodied avian invader. We show that biophysical models accurately predict TNZ and EE and that they perform better than traditional time-energy budget methods. Sensitivity analyses indicate that body temperature, metabolic rate, and feather characteristics were the most influential traits affecting model accuracy. This evaluation of common waxbill energetics represents a crucial step toward improved parameterization of biophysical models, eventually enabling accurate predictions of invasion risk for small (sub)tropical passerines.
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Affiliation(s)
- Marina Sentís
- Terrestrial Ecology Unit, Department of Biology, Faculty of Sciences, Ghent University, 9000 Ghent, Belgium
| | - Cesare Pacioni
- Terrestrial Ecology Unit, Department of Biology, Faculty of Sciences, Ghent University, 9000 Ghent, Belgium
| | - Annelies De Cuyper
- Department of Veterinary and Biosciences, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium
| | - Geert P.J. Janssens
- Department of Veterinary and Biosciences, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium
| | - Luc Lens
- Terrestrial Ecology Unit, Department of Biology, Faculty of Sciences, Ghent University, 9000 Ghent, Belgium
| | - Diederik Strubbe
- Terrestrial Ecology Unit, Department of Biology, Faculty of Sciences, Ghent University, 9000 Ghent, Belgium
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20
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Diehl JN, Alton LA, White CR, Peters A. Thermoregulatory strategies of songbird nestlings reveal limited capacity for cooling and high risk of dehydration. J Therm Biol 2023; 117:103707. [PMID: 37778091 DOI: 10.1016/j.jtherbio.2023.103707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 08/25/2023] [Accepted: 08/30/2023] [Indexed: 10/03/2023]
Abstract
How the accelerating pace of global warming will affect animal populations depends on the effects of increasing temperature across the life cycle. Developing young are sensitive to environmental challenges, often with life-long consequences, but the risks of climate warming during this period are insufficiently understood. This may be due to limited insight into physiological sensitivity and the temperatures that represent a thermal challenge for young. Here we examined the physiological and behavioural effects of increasing temperatures by measuring metabolic rate, water loss, and heat dissipation behaviours between 25-45 °C in nestlings of a small free-living songbird of temperate SE-Australia, the superb fairy-wren. We found a high and relatively narrow thermoneutral zone from 33.1 to 42.3 °C, with metabolic rate increasing and all nestlings panting above this range. Evaporative water loss sharply increased above 33.5 °C; at the same temperature, nestlings changed their posture (extended their wings) to facilitate passive heat loss. However, at all temperatures measured, water loss was insufficient to dissipate metabolically produced heat, indicating poor cooling capabilities, which persisted even when individuals were panting. While nestlings are relatively tolerant to higher temperatures, with no evidence for hyperthermia at temperatures below 42 °C, they are at a high risk of dehydration even at lower temperatures, with limited ability to mitigate this. Thus, climate warming is likely to elevate the risk dehydration, which is concerning, since it is accompanied by drier conditions.
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Affiliation(s)
- Jenna N Diehl
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia.
| | - Lesley A Alton
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia.
| | - Craig R White
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia.
| | - Anne Peters
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia.
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21
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Corregidor-Castro A, Morinay J, McKinlay SE, Ramellini S, Assandri G, Bazzi G, Glavaschi A, De Capua EL, Grapputo A, Romano A, Morganti M, Cecere JG, Pilastro A, Rubolini D. Experimental nest cooling reveals dramatic effects of heatwaves on reproduction in a Mediterranean bird of prey. GLOBAL CHANGE BIOLOGY 2023; 29:5552-5567. [PMID: 37469036 DOI: 10.1111/gcb.16888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/15/2023] [Accepted: 06/23/2023] [Indexed: 07/21/2023]
Abstract
Future climatic scenarios forecast increases in average temperatures as well as in the frequency, duration, and intensity of extreme events, such as heatwaves. Whereas behavioral adjustments can buffer direct physiological and fitness costs of exposure to excessive temperature in wild animals, these may prove more difficult during specific life stages when vagility is reduced (e.g., early developmental stages). By means of a nest cooling experiment, we tested the effects of extreme temperatures on different stages of reproduction in a cavity-nesting Mediterranean bird of prey, the lesser kestrel (Falco naumanni), facing a recent increase in the frequency of heatwaves during its breeding season. Nest temperature in a group of nest boxes placed on roof terraces was reduced by shading them from direct sunlight in 2 consecutive years (2021 and 2022). We then compared hatching failure, mortality, and nestling morphology between shaded and non-shaded (control) nest boxes. Nest temperature in control nest boxes was on average 3.9°C higher than in shaded ones during heatwaves, that is, spells of extreme air temperature (>37°C for ≥2 consecutive days) which hit the study area during the nestling-rearing phase in both years. Hatching failure markedly increased with increasing nest temperature, rising above 50% when maximum nest temperatures exceeded 44°C. Nestlings from control nest boxes showed higher mortality during heatwaves (55% vs. 10% in shaded nest boxes) and those that survived further showed impaired morphological growth (body mass and skeletal size). Hence, heatwaves occurring during the breeding period can have both strong lethal and sublethal impacts on different components of avian reproduction, from egg hatching to nestling growth. More broadly, these findings suggest that the projected future increases of summer temperatures and heatwave frequency in the Mediterranean basin and elsewhere in temperate areas may threaten the local persistence of even relatively warm-adapted species.
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Affiliation(s)
- Alejandro Corregidor-Castro
- Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italy
- Consiglio Nazionale delle Ricerche-Istituto di Ricerca sulle Acque (CNR-IRSA), Brugherio, Italy
| | - Jennifer Morinay
- Area Avifauna Migratrice, Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Bologna, Italy
- Centre for Biodiversity Dynamics, Institutt for Biologi, NTNU, Trondheim, Norway
| | - Susan E McKinlay
- Dipartimento di Scienze e Politiche Ambientali, Università degli Studi di Milano, Milan, Italy
| | - Samuele Ramellini
- Dipartimento di Scienze e Politiche Ambientali, Università degli Studi di Milano, Milan, Italy
| | - Giacomo Assandri
- Area Avifauna Migratrice, Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Bologna, Italy
- Department of Life Sciences and System Biology, University of Turin, Turin, Italy
| | - Gaia Bazzi
- Area Avifauna Migratrice, Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Bologna, Italy
| | | | | | - Alessandro Grapputo
- Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italy
- National Biodiversity Future Centre, Palermo, Italy
| | - Andrea Romano
- Dipartimento di Scienze e Politiche Ambientali, Università degli Studi di Milano, Milan, Italy
| | - Michelangelo Morganti
- Consiglio Nazionale delle Ricerche-Istituto di Ricerca sulle Acque (CNR-IRSA), Brugherio, Italy
| | - Jacopo G Cecere
- Area Avifauna Migratrice, Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Bologna, Italy
| | - Andrea Pilastro
- Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italy
- National Biodiversity Future Centre, Palermo, Italy
| | - Diego Rubolini
- Consiglio Nazionale delle Ricerche-Istituto di Ricerca sulle Acque (CNR-IRSA), Brugherio, Italy
- Dipartimento di Scienze e Politiche Ambientali, Università degli Studi di Milano, Milan, Italy
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22
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Zuluaga JD, Danner RM. Novel approaches for assessing acclimatization in birds reveal seasonal changes in peripheral heat exchange and thermoregulatory behaviors. J Exp Biol 2023; 226:jeb245772. [PMID: 37665269 DOI: 10.1242/jeb.245772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 08/23/2023] [Indexed: 09/05/2023]
Abstract
Using thermography and behavioral analyses, we found that heat exchange and thermoregulatory behaviors changed seasonally in chipping sparrows (Spizella passerina). Studies on seasonal acclimatization in birds have primarily involved metabolic measurements, few of which have investigated behaviors, and none have investigated changes in peripheral heat exchange. We captured chipping sparrows in the winter and summer of 2022 in Wilmington, North Carolina, USA, and we collected thermal images of these birds at 15.0, 27.5 and 40.0°C. We found that heat dissipation through the bill and legs changed seasonally, but surprisingly both were higher in winter than in summer. We found that heat dissipating behaviors were more common in winter, whereas heat conserving behaviors were more common in summer, and that behaviors associated with resource costs (e.g. panting) or predation risk (e.g. bill tucking) showed the most distinct differences between seasons. Meanwhile, low-cost and low-risk postural adjustments (e.g. feather adjustments and tarsus exposure) did not vary as strongly between seasons but followed similar trends. The seasonal adjustments to behaviors suggest that non-acclimatized birds must use costly thermoregulatory behaviors more frequently than acclimatized birds. The use of thermography resulted in the discovery of one completely novel behavior, and the first detection of a known behavior in a new species. Both novel behaviors aided in evaporative heat loss and occurred more commonly in winter, supporting the presence of seasonal acclimatization as evidenced by behavioral adjustments. These results provide novel insights into the process of acclimatization and suggest a role for behavioral adjustments in seasonal acclimatization.
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Affiliation(s)
- Juan D Zuluaga
- University of North Carolina Wilmington Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403-5915, USA
| | - Raymond M Danner
- University of North Carolina Wilmington Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403-5915, USA
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23
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Liu P, Lou Y, Yao J, Wang L, Møller AP, Sun Y. Variation in bill surface area is associated with local climatic factors across populations of the plain laughingthrush. Ecol Evol 2023; 13:e10535. [PMID: 37780534 PMCID: PMC10534077 DOI: 10.1002/ece3.10535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 05/31/2023] [Accepted: 09/01/2023] [Indexed: 10/03/2023] Open
Abstract
Recent studies have found that avian bill and tarsus morphology may have evolved in response to climatic conditions, and these organs play important roles in thermoregulation and water retention in extreme environments. Here, we examined whether bill surface area and tarsus length were associated with climatic conditions in the plain laughingthrush, Garrulax davidi, which mainly occurs in north China and occupies several climatic zones from east to west. We measured bill surface area and tarsus length in 321 adults from 11 populations, almost encompassing all habitat types of the species. We analyzed the relationships among these morphological traits and local climatic factors. Bill surface area was positively correlated with maximum temperature, indicating that bill surface area tended to be larger in hotter environments. Furthermore, we found a negative relationship among bill surface area and winter precipitation, indicating that bill surface area tended to be larger in arid areas. However, we did not find any relationships between tarsus length and climatic factors. These results suggest that local climates may shape the evolution of bill morphology divergence, and summer seems to be the critical season for thermoregulation in this temperate zone passerine.
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Affiliation(s)
- Pengfei Liu
- School of Life Science and TechnologyLongdong UniversityQingyangChina
| | - Yingqiang Lou
- Key Laboratory of Animal Ecology and Conservation BiologyInstitute of Zoology, Chinese Academy of ScienceBeijingChina
| | - Jingxiao Yao
- School of Life Science and TechnologyLongdong UniversityQingyangChina
| | - Linghui Wang
- School of Life Science and TechnologyLongdong UniversityQingyangChina
| | - Anders Pape Møller
- Ecologie Systématique Evolution, Université Paris–Sud, CNRS, AgroParisTechUniversité Paris–SaclayOrsay CedexFrance
| | - Yuehua Sun
- Key Laboratory of Animal Ecology and Conservation BiologyInstitute of Zoology, Chinese Academy of ScienceBeijingChina
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24
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Strubbe D, Jiménez L, Barbosa AM, Davis AJS, Lens L, Rahbek C. Mechanistic models project bird invasions with accuracy. Nat Commun 2023; 14:2520. [PMID: 37130835 PMCID: PMC10154326 DOI: 10.1038/s41467-023-38329-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 04/26/2023] [Indexed: 05/04/2023] Open
Abstract
Invasive species pose a major threat to biodiversity and inflict massive economic costs. Effective management of bio-invasions depends on reliable predictions of areas at risk of invasion, as they allow early invader detection and rapid responses. Yet, considerable uncertainty remains as to how to predict best potential invasive distribution ranges. Using a set of mainly (sub)tropical birds introduced to Europe, we show that the true extent of the geographical area at risk of invasion can accurately be determined by using ecophysiological mechanistic models that quantify species' fundamental thermal niches. Potential invasive ranges are primarily constrained by functional traits related to body allometry and body temperature, metabolic rates, and feather insulation. Given their capacity to identify tolerable climates outside of contemporary realized species niches, mechanistic predictions are well suited for informing effective policy and management aimed at preventing the escalating impacts of invasive species.
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Affiliation(s)
- Diederik Strubbe
- Terrestrial Ecology Unit (TEREC), Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Gent, Belgium.
- Center for Macroecology, Evolution, and Climate (CMEC), GLOBE Institute, University of Copenhagen, 2100, Copenhagen Ø, Denmark.
| | - Laura Jiménez
- School of Life Sciences, University of Hawai'i at Mānoa, 2538 McCarthy Mall, Honolulu, HI, 96822, USA
- Centro de Modelamiento Matemático (CNRS IRL2807), Universidad de Chile, Santiago, Chile
| | - A Márcia Barbosa
- CICGE-Centro de Investigação em Ciências Geo-Espaciais, Alameda do Monte da Virgem, 4430-146, Vila Nova de Gaia, Portugal
| | - Amy J S Davis
- Terrestrial Ecology Unit (TEREC), Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Gent, Belgium
- Ecology, Department of Biology, University of Konstanz, Universitätsstraße 10, 78464, Konstanz, Germany
| | - Luc Lens
- Terrestrial Ecology Unit (TEREC), Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Gent, Belgium
| | - Carsten Rahbek
- Center for Macroecology, Evolution, and Climate (CMEC), GLOBE Institute, University of Copenhagen, 2100, Copenhagen Ø, Denmark
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25
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Sumasgutner P, Cunningham SJ, Hegemann A, Amar A, Watson H, Nilsson JF, Andersson MN, Isaksson C. Interactive effects of rising temperatures and urbanisation on birds across different climate zones: A mechanistic perspective. GLOBAL CHANGE BIOLOGY 2023; 29:2399-2420. [PMID: 36911976 PMCID: PMC10947105 DOI: 10.1111/gcb.16645] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 05/28/2023]
Abstract
Climate change and urbanisation are among the most pervasive and rapidly growing threats to biodiversity worldwide. However, their impacts are usually considered in isolation, and interactions are rarely examined. Predicting species' responses to the combined effects of climate change and urbanisation, therefore, represents a pressing challenge in global change biology. Birds are important model taxa for exploring the impacts of both climate change and urbanisation, and their behaviour and physiology have been well studied in urban and non-urban systems. This understanding should allow interactive effects of rising temperatures and urbanisation to be inferred, yet considerations of these interactions are almost entirely lacking from empirical research. Here, we synthesise our current understanding of the potential mechanisms that could affect how species respond to the combined effects of rising temperatures and urbanisation, with a focus on avian taxa. We discuss potential interactive effects to motivate future in-depth research on this critically important, yet overlooked, aspect of global change biology. Increased temperatures are a pronounced consequence of both urbanisation (through the urban heat island effect) and climate change. The biological impact of this warming in urban and non-urban systems will likely differ in magnitude and direction when interacting with other factors that typically vary between these habitats, such as resource availability (e.g. water, food and microsites) and pollution levels. Furthermore, the nature of such interactions may differ for cities situated in different climate types, for example, tropical, arid, temperate, continental and polar. Within this article, we highlight the potential for interactive effects of climate and urban drivers on the mechanistic responses of birds, identify knowledge gaps and propose promising future research avenues. A deeper understanding of the behavioural and physiological mechanisms mediating species' responses to urbanisation and rising temperatures will provide novel insights into ecology and evolution under global change and may help better predict future population responses.
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Affiliation(s)
- Petra Sumasgutner
- Konrad Lorenz Research Centre, Core Facility for Behavior and Cognition, Department of Behavioral & Cognitive BiologyUniversity of ViennaViennaAustria
- FitzPatrick Institute of African Ornithology, DSI‐NRF Centre of ExcellenceUniversity of Cape TownCape TownSouth Africa
| | - Susan J. Cunningham
- FitzPatrick Institute of African Ornithology, DSI‐NRF Centre of ExcellenceUniversity of Cape TownCape TownSouth Africa
| | | | - Arjun Amar
- FitzPatrick Institute of African Ornithology, DSI‐NRF Centre of ExcellenceUniversity of Cape TownCape TownSouth Africa
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26
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Deviche P, Sweazea K, Angelier F. Past and future: Urbanization and the avian endocrine system. Gen Comp Endocrinol 2023; 332:114159. [PMID: 36368439 DOI: 10.1016/j.ygcen.2022.114159] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 10/18/2022] [Accepted: 11/02/2022] [Indexed: 11/10/2022]
Abstract
Urban environments are evolutionarily novel and differ from natural environments in many respects including food and/or water availability, predation, noise, light, air quality, pathogens, biodiversity, and temperature. The success of organisms in urban environments requires physiological plasticity and adjustments that have been described extensively, including in birds residing in geographically and climatically diverse regions. These studies have revealed a few relatively consistent differences between urban and non-urban conspecifics. For example, seasonally breeding urban birds often develop their reproductive system earlier than non-urban birds, perhaps in response to more abundant trophic resources. In most instances, however, analyses of existing data indicate no general pattern distinguishing urban and non-urban birds. It is, for instance, often hypothesized that urban environments are stressful, yet the activity of the hypothalamus-pituitary-adrenal axis does not differ consistently between urban and non-urban birds. A similar conclusion is reached by comparing blood indices of metabolism. The origin of these disparities remains poorly understood, partly because many studies are correlative rather than aiming at establishing causality, which effectively limits our ability to formulate specific hypotheses regarding the impacts of urbanization on wildlife. We suggest that future research will benefit from prioritizing mechanistic approaches to identify environmental factors that shape the phenotypic responses of organisms to urbanization and the neuroendocrine and metabolic bases of these responses. Further, it will be critical to elucidate whether factors affect these responses (a) cumulatively or synergistically; and (b) differentially as a function of age, sex, reproductive status, season, and mobility within the urban environment. Research to date has used various taxa that differ greatly not only phylogenetically, but also with regard to ecological requirements, social systems, propensity to consume anthropogenic food, and behavioral responses to human presence. Researchers may instead benefit from standardizing approaches to examine a small number of representative models with wide geographic distribution and that occupy diverse urban ecosystems.
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Affiliation(s)
- Pierre Deviche
- School of Life Sciences, Arizona State University, Tempe, AZ, USA.
| | - Karen Sweazea
- College of Health Solutions, Arizona State University, Phoenix, AZ, USA
| | - Frederic Angelier
- Centre d'Etudes Biologiques de Chizé, UMR7372, CNRS - La Rochelle Universite, Villiers en Bois, France
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27
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Ma L, Conradie SR, Crawford CL, Gardner AS, Kearney MR, Maclean IMD, McKechnie AE, Mi CR, Senior RA, Wilcove DS. Global patterns of climate change impacts on desert bird communities. Nat Commun 2023; 14:211. [PMID: 36639376 PMCID: PMC9839677 DOI: 10.1038/s41467-023-35814-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 01/03/2023] [Indexed: 01/15/2023] Open
Abstract
The world's warm deserts are predicted to experience disproportionately large temperature increases due to climate change, yet the impacts on global desert biodiversity remain poorly understood. Because species in warm deserts live close to their physiological limits, additional warming may induce local extinctions. Here, we combine climate change projections with biophysical models and species distributions to predict physiological impacts of climate change on desert birds globally. Our results show heterogeneous impacts between and within warm deserts. Moreover, spatial patterns of physiological impacts do not simply mirror air temperature changes. Climate change refugia, defined as warm desert areas with high avian diversity and low predicted physiological impacts, are predicted to persist in varying extents in different desert realms. Only a small proportion (<20%) of refugia fall within existing protected areas. Our analysis highlights the need to increase protection of refugial areas within the world's warm deserts to protect species from climate change.
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Affiliation(s)
- Liang Ma
- Princeton School of Public and International Affairs, Princeton University, Princeton, NJ, USA. .,School of Ecology, Shenzhen Campus of SunYat-sen University, Shenzhen, Guangdong, People's Republic of China.
| | - Shannon R Conradie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, 2 Cussonia Ave, Brummeria, Pretoria, 0184, South Africa.,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Lynnwood Rd., Pretoria, 0002, South Africa
| | - Christopher L Crawford
- Princeton School of Public and International Affairs, Princeton University, Princeton, NJ, USA
| | - Alexandra S Gardner
- Environment and Sustainability Institute, University of Exeter Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Michael R Kearney
- School of BioSciences, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Ilya M D Maclean
- Environment and Sustainability Institute, University of Exeter Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, 2 Cussonia Ave, Brummeria, Pretoria, 0184, South Africa.,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Lynnwood Rd., Pretoria, 0002, South Africa
| | - Chun-Rong Mi
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Rebecca A Senior
- Princeton School of Public and International Affairs, Princeton University, Princeton, NJ, USA.,Conservation Ecology Group, Department of Biosciences, Durham University, Durham, DH1 3LE, UK
| | - David S Wilcove
- Princeton School of Public and International Affairs, Princeton University, Princeton, NJ, USA.,Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
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28
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Cabello-Vergel J, González-Medina E, Parejo M, Abad-Gómez JM, Playà-Montmany N, Patón D, Sánchez-Guzmán JM, Masero JA, Gutiérrez JS, Villegas A. Heat tolerance limits of Mediterranean songbirds and their current and future vulnerabilities to temperature extremes. J Exp Biol 2022; 225:285906. [PMID: 36408945 PMCID: PMC9789400 DOI: 10.1242/jeb.244848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/09/2022] [Indexed: 11/22/2022]
Abstract
Songbirds are one of the groups most vulnerable to extreme heat events. Although several recent studies have assessed their physiological responses to heat, most of them have focused solely on arid-zone species. We investigated thermoregulatory responses to heat in eight small-sized songbirds occurring in the Mediterranean Basin, where heatwaves are becoming more frequent and intense. Specifically, we determined their heat tolerance limits (HTLs) and evaporative cooling efficiency, and evaluated their current and future vulnerabilities to heat in southwestern Iberia, a Mediterranean climate warming hotspot. To do this, we exposed birds to an increasing profile of air temperatures (Ta) and measured resting metabolic rate (RMR), evaporative water loss (EWL), evaporative cooling efficiency (the ratio between evaporative heat loss and metabolic heat production) and body temperature (Tb). HTL ranged between 40 and 46°C across species, and all species showed rapid increases in RMR, EWL and Tb in response to increasing Ta. However, only the crested lark (Galerida cristata) achieved an evaporative cooling efficiency greater than 1. The studied songbirds currently experience summer Ta maxima that surpass the upper critical temperatures of their thermoneutral zone and even their HTL. Our estimates indicate that five of the eight species will experience moderate risk of lethal dehydration by the end of the century. We argue that the limited heat tolerance and evaporative cooling efficiency of small-sized Mediterranean songbirds make them particularly vulnerable to heatwaves, which will be exacerbated under future climate change scenarios.
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Affiliation(s)
- Julián Cabello-Vergel
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain,Author for correspondence ()
| | - Erick González-Medina
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
| | - Manuel Parejo
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
| | - José M. Abad-Gómez
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
| | - Núria Playà-Montmany
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
| | - Daniel Patón
- Ecology Department, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
| | - Juan M. Sánchez-Guzmán
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain,Ecology in the Anthropocene, Associated Unit CSIC-UEX, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
| | - José A. Masero
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain,Ecology in the Anthropocene, Associated Unit CSIC-UEX, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
| | - Jorge S. Gutiérrez
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain,Ecology in the Anthropocene, Associated Unit CSIC-UEX, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
| | - Auxiliadora Villegas
- Conservation Biology Research Group, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain,Ecology in the Anthropocene, Associated Unit CSIC-UEX, Faculty of Sciences, University of Extremadura, 06006 Badajoz, Spain
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29
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Soravia C, Ashton BJ, Ridley AR. Periorbital temperature responses to natural air temperature variation in wild birds. J Therm Biol 2022; 109:103323. [DOI: 10.1016/j.jtherbio.2022.103323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 08/10/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022]
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30
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Swanson DL, Vézina F, McKechnie AE, Nord A. Editorial: Avian behavioral and physiological responses to challenging thermal environments and extreme weather events. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1034659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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31
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Abstract
Physiological performance declines precipitously at high body temperature (Tb), but little attention has been paid to adaptive variation in upper Tb limits among endotherms. We hypothesized that avian maximum tolerable Tb (Tbmax) has evolved in response to climate, with higher Tbmax in species exposed to high environmental heat loads or humidity-related constraints on evaporative heat dissipation. To test this hypothesis, we compared Tbmax and related variables among 53 bird species at multiple sites in South Africa with differing maximum air temperature (Tair) and humidity using a phylogenetically informed comparative framework. Birds in humid, lowland habitats had comparatively high Tbmax (mean ± SD = 45.60 ± 0.58 °C) and low normothermic Tb (Tbnorm), with a significantly greater capacity for hyperthermia (Tbmax - Tbnorm gradient = 5.84 ± 0.77 °C) compared with birds occupying cool montane (4.97 ± 0.99 °C) or hot arid (4.11 ± 0.84 °C) climates. Unexpectedly, Tbmax was significantly lower among desert birds (44.65 ± 0.60 °C), a surprising result in light of the functional importance of hyperthermia for water conservation. Our data reveal a macrophysiological pattern and support recent arguments that endotherms have evolved thermal generalization versus specialization analogous to the continuum among ectothermic animals. Specifically, a combination of modest hyperthermia tolerance and efficient evaporative cooling in desert birds is indicative of thermal specialization, whereas greater hyperthermia tolerance and less efficient evaporative cooling among species in humid lowland habitats suggest thermal generalization.
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32
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Short JC, Freeman MT, McKechnie AE. Respirometry protocols for avian thermoregulation at high air temperatures: stepped and steady-state profiles yield similar results. J Exp Biol 2022; 225:275927. [PMID: 35730660 DOI: 10.1242/jeb.244166] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 06/20/2022] [Indexed: 11/20/2022]
Abstract
Relationships between air temperature (Tair) and avian body temperature (Tb), resting metabolic rate (RMR) and evaporative water loss (EWL) during acute heat exposure can be quantified through respirometry using several approaches. One involves birds exposed to a stepped series of progressively increasing Tair setpoints for short periods (< 20-30 min), whereas a second seeks to achieve steady-state conditions by exposing birds to a single Tair for longer periods (> 1-2 h). To compare these two approaches, we measured Tb, RMR and EWL over Tair=28 °C to 44 °C in the dark-capped bulbul (Pycnonotus tricolor). The two protocols yielded indistinguishable values of Tb, RMR and EWL and related variables at most Tair values, revealing that both are appropriate for quantifying avian thermal physiology during heat exposure over the range of Tair in the present study. The stepped protocol, however, has several ethical and practical advantages.
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Affiliation(s)
- James C Short
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, P.O. Box 754, Pretoria 0001, South Africa.,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, Private Bag X20, Pretoria 0028, South Africa
| | - Marc T Freeman
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, P.O. Box 754, Pretoria 0001, South Africa.,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, Private Bag X20, Pretoria 0028, South Africa
| | - Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, P.O. Box 754, Pretoria 0001, South Africa.,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, Private Bag X20, Pretoria 0028, South Africa
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33
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Mentesana L, Hau M. Glucocorticoids in a warming world: Do they help birds to cope with high environmental temperatures? Horm Behav 2022; 142:105178. [PMID: 35561643 DOI: 10.1016/j.yhbeh.2022.105178] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 04/09/2022] [Accepted: 04/16/2022] [Indexed: 11/04/2022]
Abstract
Climate change is threatening biodiversity world-wide. One of its most prominent manifestations are rising global temperatures and higher frequencies of heat waves. High environmental temperatures may be particularly challenging for endotherms, which expend considerable parts of their energy budget and water resources on thermoregulation. Thermoregulation involves phenotypic plasticity in behavioral and physiological traits. Information on causal mechanisms that support plastic thermoregulatory strategies is key to understand how environmental information is transmitted and whether they impose trade-offs or constraints that determine how endotherms cope with climate warming. In this review, we focus on glucocorticoids, metabolic hormones that orchestrate plastic responses to various environmental stimuli including temperature. To evaluate how they may mediate behavioral and physiological responses to high environmental temperatures, we 1) briefly review the major thermoregulatory strategies in birds; 2) summarize the functions of baseline and stress-induced glucocorticoid concentrations; 3) synthesize the current knowledge of the relationship between circulating glucocorticoids and high environmental temperatures in birds; 4) generate hypotheses for how glucocorticoids may support plastic thermoregulatory responses to high environmental temperatures that occur over different time-frames (i.e., acute, short- and longer-term); and 5) discuss open questions on how glucocorticoids, and their relationship with thermoregulation, may evolve. Throughout this review we highlight that our knowledge, particularly on free-living populations, is really limited and outline promising avenues for future research. As evolutionary endocrinologists we now need to step up and identify the costs, benefits, and evolution of glucocorticoid plasticity to elucidate how they may help birds cope with a warming world.
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Affiliation(s)
- Lucia Mentesana
- Max Planck Institute for Ornithology, Eberhard-Gwinner-Str., 82319 Seewiesen, Germany.
| | - Michaela Hau
- Max Planck Institute for Ornithology, Eberhard-Gwinner-Str., 82319 Seewiesen, Germany.
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34
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Relative Water Economy Is a Useful Index of Aridity Tolerance for Australian Poephiline Finches. BIRDS 2022. [DOI: 10.3390/birds3020012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We evaluate if the iconic Australian Zebra Finch (Taeniopygia guttata) has a unique physiology or if its metabolic, thermal and hygric physiology are similar to other Australian poephiline finches, by comparing it with three other species, the arid-habitat Painted Finch (Emblema pictum) and the mesic-habitat Double-barred (Taeniopygia bichenovii) and Red-browed (Neochmia temporalis) Finches. All physiological variables responded to ambient temperature as expected. There were no species differences for any of the standard physiological variables, consistent with the hypotheses that birds are pre-adapted to arid habitats, the recent development of Australian deserts has limited opportunity for physiological adaptation, and all four species share similar behavioural and ecological traits. Nevertheless, the ambient temperature where metabolic water production equals evaporative water loss (point of relative water economy) was highest for the Zebra (19.1 °C), lower for Double-barred (16.4 °C) and Painted (15.2 °C) and lowest for Red-Browed (4.1 °C) Finches, corresponding with their general patterns of habitat aridity. The point of relative water economy may be a sensitive index for assessing a species’ tolerance of aridity because it integrates individual physiological variables. We conclude that the Zebra Finch is not a physiological outlier amongst Australian finches, but is at the end of a continuum of aridity tolerance for the four study species.
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35
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Conradie SR, Woodborne SM, Wolf BO, Pessato A, Mariette MM, McKechnie AE. Global heating poses a serious threat to Australia's birds: reply to Pacheco-Fuentes et al. CONSERVATION PHYSIOLOGY 2022; 10:coac011. [PMID: 35492411 PMCID: PMC9041427 DOI: 10.1093/conphys/coac011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/01/2022] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Affiliation(s)
- Shannon R Conradie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, 2 Cussonia Ave, Brummeria, Pretoria 0184, South Africa
- DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Lynnwood Rd., Pretoria 0002, South Africa
| | - Stephan M Woodborne
- iThemba LABS, 514 Empire Rd, Johannesburg 2193, South Africa
- Mammal Research Institute, University of Pretoria, Lynnwood Rd., Pretoria 0002, South Africa
| | - Blair O Wolf
- UNM Biology Department, University of New Mexico, Albuquerque, NM 87131, USA
| | - Anaïs Pessato
- Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University, 75 Pigdons Road, Waurn Ponds VIC 3216, Australia
| | - Mylene M Mariette
- Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University, 75 Pigdons Road, Waurn Ponds VIC 3216, Australia
- Estación Biológica de Doñana (EBD-CSIC), Calle Américo-Vespucio, Edificio I, 41092 Sevilla, Spain
| | - Andrew E McKechnie
- Corresponding author: South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, South Africa.
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36
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Lopez-Idiaquez D, Teplitsky C, Grégoire A, Fargevieille A, Rey MD, Franceschi CD, Charmantier A, Doutrelant C. Long-term decrease in coloration: a consequence of climate change? Am Nat 2022; 200:32-47. [DOI: 10.1086/719655] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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37
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Czenze ZJ, Freeman MT, Kemp R, van Jaarsveld B, Wolf BO, McKechnie AE. Efficient Evaporative Cooling and Pronounced Heat Tolerance in an Eagle-Owl, a Thick-Knee and a Sandgrouse. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.799302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Avian evaporative cooling and the maintenance of body temperature (Tb) below lethal limits during heat exposure has received more attention in small species compared to larger-bodied taxa. Here, we examined thermoregulation at air temperatures (Tair) approaching and exceeding normothermic Tb in three larger birds that use gular flutter, thought to provide the basis for pronounced evaporative cooling capacity and heat tolerance. We quantified Tb, evaporative water loss (EWL) and resting metabolic rate (RMR) in the ∼170-g Namaqua sandgrouse (Pterocles namaqua), ∼430-g spotted thick-knee (Burhinus capensis) and ∼670-g spotted eagle-owl (Bubo africanus), using flow-through respirometry and a stepped Tair profile with very low chamber humidities. All three species tolerated Tair of 56–60°C before the onset of severe hyperthermia, with maximum Tb of 43.2°C, 44.3°C, and 44.2°C in sandgrouse, thick-knees and eagle-owls, respectively. Evaporative scope (i.e., maximum EWL/minimum thermoneutral EWL) was 7.4 in sandgrouse, 12.9 in thick-knees and 7.8 in eagle-owls. The relationship between RMR and Tair varied substantially among species: whereas thick-knees and eagle-owls showed clear upper critical limits of thermoneutrality above which RMR increased rapidly and linearly, sandgrouse did not. Maximum evaporative heat loss/metabolic heat production ranged from 2.8 (eagle-owls) to 5.5 (sandgrouse), the latter the highest avian value yet reported. Our data reveal some larger species with gular flutter possess pronounced evaporative cooling capacity and heat tolerance and, when taken together with published data, show thermoregulatory performance varies widely among species larger than 250 g. Our data for Namaqua sandgrouse reveal unexpectedly pronounced variation in the metabolic costs of evaporative cooling within the genus Pterocles.
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38
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Czenze ZJ, Smit B, Jaarsveld B, Freeman MT, McKechnie AE. Caves, crevices and cooling capacity: Roost microclimate predicts heat tolerance in bats. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13918] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Zenon J. Czenze
- South African Research Chair in Conservation Physiology South African National Biodiversity Institute Pretoria South Africa
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Pretoria South Africa
| | - Ben Smit
- Department of Zoology and Entomology Rhodes University Makhanda South Africa
| | - Barry Jaarsveld
- South African Research Chair in Conservation Physiology South African National Biodiversity Institute Pretoria South Africa
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Pretoria South Africa
| | - Marc T. Freeman
- South African Research Chair in Conservation Physiology South African National Biodiversity Institute Pretoria South Africa
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Pretoria South Africa
| | - Andrew E. McKechnie
- South African Research Chair in Conservation Physiology South African National Biodiversity Institute Pretoria South Africa
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Pretoria South Africa
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Playà‐Montmany N, González‐Medina E, Cabello‐Vergel J, Parejo M, Abad‐Gómez JM, Sánchez‐Guzmán JM, Villegas A, Masero JA. The thermoregulatory role of relative bill and leg surface areas in a Mediterranean population of Great tit ( Parus major). Ecol Evol 2021; 11:15936-15946. [PMID: 34824801 PMCID: PMC8601919 DOI: 10.1002/ece3.8263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 09/15/2021] [Accepted: 10/07/2021] [Indexed: 11/07/2022] Open
Abstract
There is growing evidence on the role of legs and bill as 'thermal windows' in birds coping with heat stress. However, there is a lack of empirical work examining the relationship between the relative bill and/or leg surface areas and key thermoregulatory traits such as the limits of the thermoneutral zone (TNZ) or the cooling efficiency at high temperatures. Here, we explored this relationship in a Mediterranean population of Great tit (Parus major) facing increasing thermal stress in its environment. The lower and upper critical limits of the TNZ were found to be 17.7 ± 1.6ºC and 34.5 ± 0.7°C, respectively, and the basal metabolic rate was 0.96 ± 0.12 ml O2 min-1 on average. The evaporative water loss (EWL) inflection point was established at 31.85 ± 0.27°C and was not significantly different from the value of the upper critical limit. No significant relationship was observed between the relative bill or tarsi size and TNZ critical limits, breadth, mass-independent VO2, or mass-independent EWL at any environmental temperature (from 10 to 40°C). However, Great tit males (but not females) with larger tarsi areas (a proxy of leg surface area) showed higher cooling efficiencies at 40°C. We found no support for the hypothesis that the bill surface area plays a significant role as a thermal window in Great tits, but the leg surface areas may play a role in males' physiological responses to high temperatures. On the one hand, we argue that the studied population occupies habitats with available microclimates and fresh water for drinking during summer, so active heat dissipation by EWL might be favored instead of dry heat loss through the bill surface. Conversely, male dominance behaviors could imply a greater dependence on cutaneous EWL through the upper leg surfaces as a consequence of higher exposure to harsh environmental conditions than faced by females.
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Affiliation(s)
- Núria Playà‐Montmany
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Erick González‐Medina
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Julián Cabello‐Vergel
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Manuel Parejo
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - José M. Abad‐Gómez
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Juan M. Sánchez‐Guzmán
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
- Ecology in the AnthropoceneAssociated Unit CSIC‐UEXFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - Auxiliadora Villegas
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
- Ecology in the AnthropoceneAssociated Unit CSIC‐UEXFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
| | - José A. Masero
- Conservation Biology Research GroupFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
- Ecology in the AnthropoceneAssociated Unit CSIC‐UEXFacultad de CienciasUniversidad de ExtremaduraBadajozSpain
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40
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Flores-Santin J, Burggren WW. Beyond the Chicken: Alternative Avian Models for Developmental Physiological Research. Front Physiol 2021; 12:712633. [PMID: 34744759 PMCID: PMC8566884 DOI: 10.3389/fphys.2021.712633] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/13/2021] [Indexed: 12/23/2022] Open
Abstract
Biomedical research focusing on physiological, morphological, behavioral, and other aspects of development has long depended upon the chicken (Gallus gallus domesticus) as a key animal model that is presumed to be typical of birds and generally applicable to mammals. Yet, the modern chicken in its many forms is the result of artificial selection more intense than almost any other domesticated animal. A consequence of great variation in genotype and phenotype is that some breeds have inherent aberrant physiological and morphological traits that may show up relatively early in development (e.g., hypertension, hyperglycemia, and limb defects in the broiler chickens). While such traits can be useful as models of specific diseases, this high degree of specialization can color general experimental results and affect their translational value. Against this background, in this review we first consider the characteristics that make an animal model attractive for developmental research (e.g., accessibility, ease of rearing, size, fecundity, development rates, genetic variation, etc.). We then explore opportunities presented by the embryo to adult continuum of alternative bird models, including quail, ratites, songbirds, birds of prey, and corvids. We conclude by indicating that expanding developmental studies beyond the chicken model to include additional avian groups will both validate the chicken model as well as potentially identify even more suitable avian models for answering questions applicable to both basic biology and the human condition.
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Affiliation(s)
- Josele Flores-Santin
- Facultad de Ciencias, Biologia, Universidad Autónoma del Estado de Mexico, Toluca, Mexico
| | - Warren W. Burggren
- Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas Denton, Denton, TX, United States
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41
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Ngcamphalala CA, Bouwer M, Nicolson SW, Ganswindt A, McKechnie AE. Experimental Manipulation of Air Temperature in Captivity Appears Unsuitable for Evaluating Fecal Glucocorticoid Metabolite Responses of Wild-Caught Birds to Heat Exposure. Physiol Biochem Zool 2021; 94:330-337. [PMID: 34292861 DOI: 10.1086/716043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractNoninvasive measurement of stress-related alterations in fecal glucocorticoid metabolite (fGCM) concentrations has considerable potential for quantifying physiological responses to very hot weather in free-ranging birds, but practical considerations related to sampling will often make this method feasible only for habituated study populations. Here we evaluate an alternate approach, the use of experimentally manipulated thermal environments for evaluating stress responses to high environmental temperatures in wild-caught birds housed in captivity. Using an enzyme immunoassay utilizing antibodies against 5ß-pregnane-3α,11ß,21-triol-20-one-CMO∶BSA (tetrahydrocorticosterone), we quantified fGCMs in captive individuals of three southern African arid-zone species (southern pied babblers [Turdoides bicolor], white-browed sparrow-weavers [Plocepasser mahali], and southern yellow-billed hornbills [Tockus leucomelas]) experiencing daily air temperature maxima (Tmax) ranging from 30°-32°C to 42°-44°C. For none of the three species did Tmax emerge as a significant predictor of elevated fGCM concentrations, and no stress response to simulated hot weather was evident. The apparent lack of a stress response to Tmax = 42°C in captive southern pied babblers contrasts with linear increases in fGCMs at Tmax > 38°C in free-ranging conspecifics. The lack of an effect of Tmax on fGCM levels may potentially be explained by several factors, including differences in operative temperatures and the availability of water and food between free-ranging and captive settings or the stress effect of captivity itself. Our results suggest that experimental manipulations of thermal environments experienced by wild-caught captive birds have limited usefulness for testing hypotheses concerning the effects of hot weather events on fGCM (and, by extension, glucocorticoid) concentrations.
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McKechnie AE, Rushworth IA, Myburgh F, Cunningham SJ. Mortality among birds and bats during an extreme heat event in eastern South Africa. AUSTRAL ECOL 2021. [DOI: 10.1111/aec.13025] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Andrew E. McKechnie
- South African Research Chair in Conservation Physiology South African National Biodiversity Institute P.O. Box 754 Pretoria0001South Africa
- DSI‐NRF Centre of Excellence at the FitzPatrick Institute Department of Zoology and Entomology University of Pretoria PretoriaSouth Africa
| | - Ian A. Rushworth
- Ezemvelo KZN Wildlife Pietermaritzburg KwaZulu‐NatalSouth Africa
| | - Ferdi Myburgh
- Ezemvelo KZN Wildlife Pietermaritzburg KwaZulu‐NatalSouth Africa
| | - Susan J. Cunningham
- FitzPatrick Institute of African Ornithology DSI‐NRF Centre of Excellence University of Cape Town Rondebosch South Africa
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43
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Franklin CE, Hoppeler HH. Elucidating mechanism is important in forecasting the impact of a changing world on species survival. J Exp Biol 2021; 224:224/Suppl_1/jeb242284. [PMID: 33627471 DOI: 10.1242/jeb.242284] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
| | - Hans H Hoppeler
- Department of Anatomy, University of Bern, 3000 Bern, Switzerland
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44
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van Jaarsveld B, Bennett NC, Czenze ZJ, Kemp R, van de Ven TMFN, Cunningham SJ, McKechnie AE. How hornbills handle heat: sex-specific thermoregulation in the southern yellow-billed hornbill. J Exp Biol 2021; 224:jeb.232777. [PMID: 33504586 DOI: 10.1242/jeb.232777] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 01/06/2021] [Indexed: 12/22/2022]
Abstract
At a global scale, thermal physiology is correlated with climatic variables such as temperature and aridity. There is also evidence that thermoregulatory traits vary with fine-scale microclimate, but this has received less attention in endotherms. Here, we test the hypothesis that avian thermoregulation varies with microclimate and behavioural constraints in a non-passerine bird. Male and female southern yellow-billed hornbills (Tockus leucomelas) experience markedly different microclimates while breeding, with the female sealing herself into a tree cavity and moulting all her flight feathers during the breeding attempt, becoming entirely reliant on the male for provisioning. We examined interactions between resting metabolic rate (RMR), evaporative water loss (EWL) and core body temperature (T b) at air temperatures (T a) between 30°C and 52°C in male and female hornbills, and quantified evaporative cooling efficiencies and heat tolerance limits. At thermoneutral T a, neither RMR, EWL nor T b differed between sexes. At T a >40°C, however, RMR and EWL of females were significantly lower than those of males, by ∼13% and ∼17%, respectively, despite similar relationships between T b and T a, maximum ratio of evaporative heat loss to metabolic heat production and heat tolerance limits (∼50°C). These sex-specific differences in hornbill thermoregulation support the hypothesis that avian thermal physiology can vary within species in response to fine-scale microclimatic factors. In addition, Q 10 for RMR varied substantially, with Q 10 ≤2 in some individuals, supporting recent arguments that active metabolic suppression may be an underappreciated aspect of endotherm thermoregulation in the heat.
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Affiliation(s)
- Barry van Jaarsveld
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria 0001, South Africa .,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Nigel C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0001, South Africa
| | - Zenon J Czenze
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria 0001, South Africa.,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Ryno Kemp
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria 0001, South Africa.,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Tanja M F N van de Ven
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.,Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa
| | - Susan J Cunningham
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
| | - Andrew E McKechnie
- South African Research Chair in Conservation Physiology, South African National Biodiversity Institute, Pretoria 0001, South Africa.,DSI-NRF Centre of Excellence at the FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
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