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McNew SM, Taff CC, Vitousek MN. Manipulation of a social signal affects DNA methylation of a stress-related gene in a free-living bird. J Exp Biol 2024; 227:jeb246819. [PMID: 39022893 DOI: 10.1242/jeb.246819] [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: 10/06/2023] [Accepted: 07/02/2024] [Indexed: 07/20/2024]
Abstract
Social status directly affects the health of humans and other animals. Low status individuals receive more antagonistic encounters, have fewer supportive relationships and have worse health outcomes. However, the physiological and cellular processes that mediate the relationship between the social environment and health are incompletely known. Epigenetic regulation of the hypothalamic-pituitary-adrenal (HPA) axis, the neuroendocrine pathway that activates in response to stressors, may be one process that is sensitive to the social environment. Here, we experimentally manipulated plumage, a key social signal in female tree swallows (Tachycineta bicolor) and quantified methylation of four genes in the HPA axis before and after treatment. We found that dulling the white breast plumage affected methylation in one gene, CRHR1; however, the effect depended on the original brightness of the bird. Methylation in this gene was correlated with baseline corticosterone levels, suggesting that DNA methylation of CRHR1 helps regulate glucocorticoid production in this species. Methylation in two other genes, FKBP5 and GR, changed over the course of the experiment, independent of treatment. These results show that methylation of these genes is labile into adulthood and suggest that epigenetic regulation of the HPA axis could help birds respond to current environmental conditions.
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Affiliation(s)
- Sabrina M McNew
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY 14850, USA
- Department of Ecology & Evolutionary Biology, University of Arizona, Tucson, AZ 85719, USA
| | - Conor C Taff
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY 14850, USA
- Department of Biology, Colby College, Waterville, ME 04901, USA
| | - Maren N Vitousek
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY 14850, USA
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2
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Neely WJ, Martins RA, Mendonça da Silva CM, Ferreira da Silva T, Fleck LE, Whetstone RD, Woodhams DC, Cook WH, Prist PR, Valiati VH, Greenspan SE, Tozetti AM, Earley RL, Becker CG. Linking microbiome and stress hormone responses in wild tropical treefrogs across continuous and fragmented forests. Commun Biol 2023; 6:1261. [PMID: 38087051 PMCID: PMC10716138 DOI: 10.1038/s42003-023-05600-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023] Open
Abstract
The amphibian skin microbiome is an important component of anti-pathogen defense, but the impact of environmental change on the link between microbiome composition and host stress remains unclear. In this study, we used radiotelemetry and host translocation to track microbiome composition and function, pathogen infection, and host stress over time across natural movement paths for the forest-associated treefrog, Boana faber. We found a negative correlation between cortisol levels and putative microbiome function for frogs translocated to forest fragments, indicating strong integration of host stress response and anti-pathogen potential of the microbiome. Additionally, we observed a capacity for resilience (resistance to structural change and functional loss) in the amphibian skin microbiome, with maintenance of putative pathogen-inhibitory function despite major temporal shifts in microbiome composition. Although microbiome community composition did not return to baseline during the study period, the rate of microbiome change indicated that forest fragmentation had more pronounced effects on microbiome composition than translocation alone. Our findings reveal associations between stress hormones and host microbiome defenses, with implications for resilience of amphibians and their associated microbes facing accelerated tropical deforestation.
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Affiliation(s)
- Wesley J Neely
- Department of Biology, The University of Alabama, Tuscaloosa, AL, 35487, USA.
- Department of Biology, Texas State University, San Marcos, TX, 78666, USA.
| | - Renato A Martins
- Department of Biology, and Center for Infectious Disease Dynamics, One Health Microbiome Center, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Camila M Mendonça da Silva
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Tainá Ferreira da Silva
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Lucas E Fleck
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Ross D Whetstone
- Department of Biology, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - W Harrison Cook
- Department of Biology, The University of Alabama, Tuscaloosa, AL, 35487, USA
| | - Paula R Prist
- EcoHealth Alliance, 520 Eight Avenue, Suite 1200, New York, NY, 10018, USA
| | - Victor H Valiati
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Sasha E Greenspan
- Department of Biology, The University of Alabama, Tuscaloosa, AL, 35487, USA
| | - Alexandro M Tozetti
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Ryan L Earley
- Department of Biology, The University of Alabama, Tuscaloosa, AL, 35487, USA
| | - C Guilherme Becker
- Department of Biology, and Center for Infectious Disease Dynamics, One Health Microbiome Center, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
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3
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Hukkanen M, Hsu B, Cossin‐Sevrin N, Crombecque M, Delaunay A, Hollmen L, Kaukonen R, Konki M, Lund R, Marciau C, Stier A, Ruuskanen S. From maternal glucocorticoid and thyroid hormones to epigenetic regulation of offspring gene expression: An experimental study in a wild bird species. Evol Appl 2023; 16:1753-1769. [PMID: 38020869 PMCID: PMC10660793 DOI: 10.1111/eva.13598] [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: 03/06/2023] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 12/01/2023] Open
Abstract
Offspring phenotype at birth is determined by its genotype and the prenatal environment including exposure to maternal hormones. Variation in both maternal glucocorticoids and thyroid hormones can affect offspring phenotype, but the underlying molecular mechanisms, especially those contributing to long-lasting effects, remain unclear. Epigenetic changes (such as DNA methylation) have been postulated as mediators of long-lasting effects of early-life environment. In this study, we determined the effects of elevated prenatal glucocorticoid and thyroid hormones on handling stress response (breath rate) as well as DNA methylation and gene expression of glucocorticoid receptor (GR) and thyroid hormone receptor (THR) in great tits (Parus major). Eggs were injected before incubation onset with corticosterone (the main avian glucocorticoid) and/or thyroid hormones (thyroxine and triiodothyronine) to simulate variation in maternal hormone deposition. Breath rate during handling and gene expression of GR and THR were evaluated 14 days after hatching. Methylation status of GR and THR genes was analyzed from the longitudinal blood cells sampled 7 and 14 days after hatching, as well as the following autumn. Elevated prenatal corticosterone level significantly increased the breath rate during handling, indicating an enhanced metabolic stress response. Prenatal corticosterone manipulation had CpG-site-specific effects on DNA methylation at the GR putative promoter region, while it did not significantly affect GR gene expression. GR expression was negatively associated with earlier hatching date and chick size. THR methylation or expression did not exhibit any significant relationship with the hormonal treatments or the examined covariates, suggesting that TH signaling may be more robust due to its crucial role in development. This study provides some support to the hypothesis suggesting that maternal corticosterone may influence offspring metabolic stress response via epigenetic alterations, yet their possible adaptive role in optimizing offspring phenotype to the prevailing conditions, context-dependency, and the underlying molecular interplay needs further research.
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Affiliation(s)
- Mikaela Hukkanen
- Institute for Molecular Medicine FinlandUniversity of HelsinkiHelsinkiFinland
| | - Bin‐Yan Hsu
- Department of BiologyUniversity of TurkuTurkuFinland
| | | | | | - Axelle Delaunay
- Institut des Sciences de l'Evolution de Montpellier (ISEM)Université de Montpellier, CNRS, IRD, EPHEMontpellierFrance
| | - Lotta Hollmen
- Department of BiologyUniversity of TurkuTurkuFinland
| | - Riina Kaukonen
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityTurkuFinland
| | - Mikko Konki
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityTurkuFinland
- Turku Doctoral Programme of Molecular MedicineUniversity of TurkuTurkuFinland
| | - Riikka Lund
- Turku Bioscience CentreUniversity of Turku and Åbo Akademi UniversityTurkuFinland
| | - Coline Marciau
- Department of BiologyUniversity of TurkuTurkuFinland
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTasmaniaAustralia
| | - Antoine Stier
- Department of BiologyUniversity of TurkuTurkuFinland
- Institut Pluridisciplinaire Hubert Curien, UMR 7178University of Strasbourg, CNRSStrasbourgFrance
| | - Suvi Ruuskanen
- Department of BiologyUniversity of TurkuTurkuFinland
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
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4
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Dandi Ε, Spandou E, Dalla C, Tata DA. Τhe neuroprotective role of environmental enrichment against behavioral, morphological, neuroendocrine and molecular changes following chronic unpredictable mild stress: A systematic review. Eur J Neurosci 2023; 58:3003-3025. [PMID: 37461295 DOI: 10.1111/ejn.16089] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 06/12/2023] [Accepted: 06/25/2023] [Indexed: 08/16/2023]
Abstract
Environmental factors interact with biological and genetic factors influencing the development and well-being of an organism. The interest in better understanding the role of environment on behavior and physiology led to the development of animal models of environmental manipulations. Environmental enrichment (EE), an environmental condition that allows cognitive and sensory stimulation as well as social interaction, improves cognitive function, reduces anxiety and depressive-like behavior and promotes neuroplasticity. In addition, it exerts protection against neurodegenerative disorders, cognitive aging and deficits aggravated by stressful experiences. Given the beneficial effects of EE on the brain and behavior, preclinical studies have focused on its protective role as an alternative, non-invasive manipulation, to help an organism to cope better with stress. A valid, reliable and effective animal model of chronic stress that enhances anxiety and depression-like behavior is the chronic unpredictable mild stress (CUMS). The variety of stressors and the unpredictability in the time and sequence of exposure to prevent habituation, render CUMS an ethologically relevant model. CUMS has been associated with dysregulation of the hypothalamic-pituitary-adrenal axis, elevation in the basal levels of stress hormones, reduction in brain volume, dendritic atrophy and alterations in markers of synaptic plasticity. Although numerous studies have underlined the compensatory role of EE against the negative effects of various chronic stress regimens (e.g. restraint and social isolation), research concerning the interaction between EE and CUMS is sparse. The purpose of the current systematic review is to present up-to-date research findings regarding the protective role of EE against the negative effects of CUMS.
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Affiliation(s)
- Εvgenia Dandi
- Laboratory of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Evangelia Spandou
- Laboratory of Experimental Physiology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Christina Dalla
- Department of Pharmacology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Despina A Tata
- Laboratory of Cognitive Neuroscience, School of Psychology, Aristotle University of Thessaloniki, Thessaloniki, Greece
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5
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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: 5] [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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6
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Majer AD, Paitz RT, Tricola GM, Geduldig JE, Litwa HP, Farmer JL, Prevelige BR, McMahon EK, McNeely T, Sisson ZR, Frenz BJ, Ziur AD, Clay EJ, Eames BD, McCollum SE, Haussmann MF. The response to stressors in adulthood depends on the interaction between prenatal exposure to glucocorticoids and environmental context. Sci Rep 2023; 13:6180. [PMID: 37061562 PMCID: PMC10105737 DOI: 10.1038/s41598-023-33447-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 04/12/2023] [Indexed: 04/17/2023] Open
Abstract
Maternal stress during reproduction can influence how offspring respond to stress later in life. Greater lifetime exposure to glucocorticoid hormones released during stress is linked to greater risks of behavioral disorders, disease susceptibility, and mortality. The immense variation in individual's stress responses is explained, in part, by prenatal glucocorticoid exposure. To explore the long-term effects of embryonic glucocorticoid exposure, we injected Japanese quail (Coturnix japonica) eggs with corticosterone. We characterized the endocrine stress response in offspring and measured experienced aggression at three different ages. We found that prenatal glucocorticoid exposure affected (1) the speed at which the stress response was terminated suggesting dysregulated negative feedback, (2) baseline corticosterone levels in a manner dependent on current environmental conditions with higher levels of experienced aggression associated with higher levels of baseline corticosterone, (3) the magnitude of an acute stress response based on baseline concentrations. We finish by proposing a framework that can be used to test these findings in future work. Overall, our findings suggest that the potential adaptive nature of prenatal glucocorticoid exposure is likely dependent on environmental context and may also be tempered by the negative effects of longer exposure to glucocorticoids each time an animal faces a stressor.
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Affiliation(s)
- Ariana D Majer
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, IL, 61790, USA
| | - Gianna M Tricola
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Jack E Geduldig
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Hannah P Litwa
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Jenna L Farmer
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | | | - Elyse K McMahon
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Taylor McNeely
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Zach R Sisson
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Brian J Frenz
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Alexis D Ziur
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Emily J Clay
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | - Brad D Eames
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA
| | | | - Mark F Haussmann
- Department of Biology, Bucknell University, Lewisburg, PA, 17837, USA.
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7
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Repression of transcription by the glucocorticoid receptor: A parsimonious model for the genomics era. J Biol Chem 2021; 296:100687. [PMID: 33891947 PMCID: PMC8141881 DOI: 10.1016/j.jbc.2021.100687] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 12/15/2022] Open
Abstract
Glucocorticoids are potent anti-inflammatory drugs that are used to treat an extraordinary range of human disease, including COVID-19, underscoring the ongoing importance of understanding their molecular mechanisms. Early studies of GR signaling led to broad acceptance of models in which glucocorticoid receptor (GR) monomers tether repressively to inflammatory transcription factors, thus abrogating inflammatory gene expression. However, newer data challenge this core concept and present an exciting opportunity to reframe our understanding of GR signaling. Here, we present an alternate, two-part model for transcriptional repression by glucocorticoids. First, widespread GR-mediated induction of transcription results in rapid, primary repression of inflammatory gene transcription and associated enhancers through competition-based mechanisms. Second, a subset of GR-induced genes, including targets that are regulated in coordination with inflammatory transcription factors such as NF-κB, exerts secondary repressive effects on inflammatory gene expression. Within this framework, emerging data indicate that the gene set regulated through the cooperative convergence of GR and NF-κB signaling is central to the broad clinical effectiveness of glucocorticoids in terminating inflammation and promoting tissue repair.
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8
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Zimmer C, Taff CC, Ardia DR, Rose AP, Aborn DA, Johnson LS, Vitousek MN. Environmental unpredictability shapes glucocorticoid regulation across populations of tree swallows. Sci Rep 2020; 10:13682. [PMID: 32792550 PMCID: PMC7426823 DOI: 10.1038/s41598-020-70161-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 07/23/2020] [Indexed: 12/12/2022] Open
Abstract
The ability to respond appropriately to challenges is an important contributor to fitness. Variation in the regulation of glucocorticoid hormones, which mediate the phenotypic response to challenges, can therefore influence the ability to persist in a given environment. We compared stress responsiveness in four populations of tree swallows (Tachycineta bicolor) breeding under different environmental conditions to evaluate support for different selective pressures in driving the evolution of glucocorticoid regulation. In accordance with the environmental unpredictability hypothesis, stronger stress responses were seen in more unpredictable environments. Contrary to the reproductive value hypothesis, the stress response was not lower in populations engaging in more valuable reproductive attempts. Populations with stronger stress responses also had stronger negative feedback, which supports a “mitigating” rather than a “magnifying” effect of negative feedback on stress responses. These results suggest that combining a robust stress response with strong negative feedback may be important for persisting in unpredictable or rapidly changing environments.
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Affiliation(s)
- Cedric Zimmer
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA.
| | - Conor C Taff
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA.,Cornell Lab of Ornithology, Ithaca, NY, 14850, USA
| | - Daniel R Ardia
- Department of Biology, Franklin and Marshall College, Lancaster, PA, 17604, USA
| | - Alexandra P Rose
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, 80303, USA
| | - David A Aborn
- Biology, Geology and Environmental Science, The University of Tennessee Chattanooga, Chattanooga, TN, 37403, USA
| | - L Scott Johnson
- Department of Biological Sciences, Towson University, Towson, MD, 21252, USA
| | - Maren N Vitousek
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA.,Cornell Lab of Ornithology, Ithaca, NY, 14850, USA
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9
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Narayan EJ, Forsburg ZR, Davis DR, Gabor CR. Non-invasive Methods for Measuring and Monitoring Stress Physiology in Imperiled Amphibians. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00431] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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10
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Fischer CP, Romero LM. Chronic captivity stress in wild animals is highly species-specific. CONSERVATION PHYSIOLOGY 2019; 7:coz093. [PMID: 31824674 PMCID: PMC6892464 DOI: 10.1093/conphys/coz093] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/04/2019] [Accepted: 10/13/2019] [Indexed: 05/05/2023]
Abstract
Wild animals are brought into captivity for many reasons-conservation, research, agriculture and the exotic pet trade. While the physical needs of animals are met in captivity, the conditions of confinement and exposure to humans can result in physiological stress. The stress response consists of the suite of hormonal and physiological reactions to help an animal survive potentially harmful stimuli. The adrenomedullary response results in increased heart rate and muscle tone (among other effects); elevated glucocorticoid (GC) hormones help to direct resources towards immediate survival. While these responses are adaptive, overexposure to stress can cause physiological problems, such as weight loss, changes to the immune system and decreased reproductive capacity. Many people who work with wild animals in captivity assume that they will eventually adjust to their new circumstances. However, captivity may have long-term or permanent impacts on physiology if the stress response is chronically activated. We reviewed the literature on the effects of introduction to captivity in wild-caught individuals on the physiological systems impacted by stress, particularly weight changes, GC regulation, adrenomedullary regulation and the immune and reproductive systems. This paper did not review studies on captive-born animals. Adjustment to captivity has been reported for some physiological systems in some species. However, for many species, permanent alterations to physiology may occur with captivity. For example, captive animals may have elevated GCs and/or reduced reproductive capacity compared to free-living animals even after months in captivity. Full adjustment to captivity may occur only in some species, and may be dependent on time of year or other variables. We discuss some of the methods that can be used to reduce chronic captivity stress.
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Affiliation(s)
| | - L Michael Romero
- Department of Biology, 200 College Ave. Tufts University, Medford, MA 02155 USA
- Corresponding author: Department of Biology, Medford, MA 02155, USA.
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