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Scheun J, Venter L, Ganswindt A. A frog in hot water: the effect of temperature elevation on the adrenal stress response of an African amphibian. PeerJ 2024; 12:e17847. [PMID: 39157773 PMCID: PMC11328835 DOI: 10.7717/peerj.17847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 07/10/2024] [Indexed: 08/20/2024] Open
Abstract
Amphibians, with their unique physiology and habitat requirements, are especially vulnerable to changes in environmental temperatures. While the activation of the physiological stress response can help to mitigate the impact of such habitat alteration, chronic production of elevated glucocorticoid levels can be deleterious in nature. There is no empirical evidence indicating the physiological response of African amphibians to temperature changes, where individuals are unable to emigrate away from potential stressors. To rectify this, we used the edible bullfrog (Pyxicephalus edulis) as a model species to determine the effect of elevated temperature on the adrenocortical response of the species using a recently established matrix. While a control group was kept at a constant temperature (25 °C) throughout the study period, an experimental group was exposed to control (25 °C) and elevated temperatures (30 °C). Mucous swabs were collected throughout the study period to determine dermal glucocorticoid (dGC) concentrations, as a proxy for physiological stress. In addition to this, individual body mass measurements were collected. The results showed that individuals within the experimental group who experienced increased temperatures had significantly elevated dGC levels compared to the control animals. Furthermore, there was a significant difference in the percentage mass change between experimental and control animals . These findings indicate the physiological sensitivity of the edible bullfrog to a thermal stressor in captivity. While this study shows the importance of proper amphibian management within the captive environment, it also highlights the coming danger of global climate change to this and similar amphibian species.
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Affiliation(s)
- Juan Scheun
- Department Nature Conservation, Faculty of Science, Tshwane University of Pretoria, Pretoria, Gauteng, South Africa
- Mammal Research Institute, Department Zoology and Entomology, University of Pretoria, Pretoria, Gauteng, South Africa
| | - Leanne Venter
- Department Nature Conservation, Faculty of Science, Tshwane University of Pretoria, Pretoria, Gauteng, South Africa
| | - Andre Ganswindt
- Mammal Research Institute, Department Zoology and Entomology, University of Pretoria, Pretoria, Gauteng, South Africa
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2
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Clarke E, Heugten KAV, Tollefson TN, Ridgley FN, Smith D, Brown JL, Scott H, Minter LJ. Comparison of Corticosterone Concentrations in Dermal Secretions and Urine in Free-Ranging Marine Toads ( Rhinella marina) in Human Care. Vet Med Int 2023; 2023:1467549. [PMID: 37766874 PMCID: PMC10522434 DOI: 10.1155/2023/1467549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 08/25/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Corticosterone concentrations have been measured in amphibians by collecting blood or urine samples. However, blood sampling is invasive, and urine can be difficult to collect. A novel method of swabbing the skin of an amphibian has been utilized in numerous species but has not been verified in marine toads (Rhinella marina). This pilot study tested dermal swabs as a noninvasive method for collecting and measuring dermal corticosterone secretions. Swabs were used to collect dermal secretion samples from sixty-six free-ranging marine toads collected on Zoo Miami grounds. The subsequent day the toads were shipped to the North Carolina Zoo where dermal samples were collected again. Additional dermal and urine samples were collected on days 9, 15, 32, and 62 under human care to measure corticosterone concentrations. There was no significant correlation (P ≥ 0.05) noted between corticosterone concentrations reported in dermal swabs and those in urine samples at all four of the euthanasia time points or between the corticosterone concentrations reported in either urine or dermal swabs and the weight of the toads. Dermal swab concentrations (ng/mL) were significantly higher (P ≤ 0.05) on the day of capture (0.64 ± 0.03) and the day of arrival (0.67 ± 0.03) than on day 15 (0.47 ± 0.03). The urine corticosterone concentrations decreased while the toads were in human care with a significant decrease (P ≤ 0.05) between days 9 (0.45 ± 0.07) and 32 (0.21 ± 0.06). This study demonstrated that dermal swabs can be used to collect marine toad corticosterone concentration samples.
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Affiliation(s)
- Emma Clarke
- Department of Clinical Sciences, North Carolina State University, College of Veterinary Medicine, 1060 William Moore Dr., Raleigh, NC 27607, USA
| | - Kimberly Ange-van Heugten
- Department of Animal Science, North Carolina State University, 120 W. Broughton Dr., Raleigh, NC 27695, USA
- Environment Medicine Consortium, North Carolina State University, 1060 William Moore Dr., Raleigh, NC 27607, USA
| | - Troy N. Tollefson
- Mazuri® Exotic Animal Nutrition, PMI Nutrition, 4001 Lexington Ave. North, Arden Hills, MN 55126, USA
| | - Frank N. Ridgley
- The Conservation and Research Department, Zoo Miami, 12400 SW 152nd St., Miami, FL 33177, USA
| | - Dustin Smith
- North Carolina Zoo, 4401 Zoo Pkwy, Asheboro, NC 27205, USA
| | - Janine L. Brown
- Smithsonian Conservation Biology Institute, 1500 Remount Rd., Front Royal, VA 22630, USA
| | - Heather Scott
- North Carolina Zoo, 4401 Zoo Pkwy, Asheboro, NC 27205, USA
| | - Larry J. Minter
- Department of Clinical Sciences, North Carolina State University, College of Veterinary Medicine, 1060 William Moore Dr., Raleigh, NC 27607, USA
- Environment Medicine Consortium, North Carolina State University, 1060 William Moore Dr., Raleigh, NC 27607, USA
- North Carolina Zoo, 4401 Zoo Pkwy, Asheboro, NC 27205, USA
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3
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Ruthsatz K, Rico-Millan R, Eterovick PC, Gomez-Mestre I. Exploring water-borne corticosterone collection as a non-invasive tool in amphibian conservation physiology: benefits, limitations and future perspectives. CONSERVATION PHYSIOLOGY 2023; 11:coad070. [PMID: 37663928 PMCID: PMC10472495 DOI: 10.1093/conphys/coad070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 08/03/2023] [Accepted: 08/26/2023] [Indexed: 09/05/2023]
Abstract
Global change exposes wildlife to a variety of environmental stressors and is affecting biodiversity worldwide, with amphibian population declines being at the forefront of the global biodiversity crisis. The use of non-invasive methods to determine the physiological state in response to environmental stressors is therefore an important advance in the field of conservation physiology. The glucocorticoid hormone corticosterone (CORT) is one useful biomarker to assess physiological stress in amphibians, and sampling water-borne (WB) CORT is a novel, non-invasive collection technique. Here, we tested whether WB CORT can serve as a valid proxy of organismal levels of CORT in larvae of the common frog (Rana temporaria). We evaluated the association between tissue and WB CORT levels sampled from the same individuals across ontogenetic stages, ranging from newly hatched larvae to froglets at 10 days after metamorphosis. We also investigated how both tissue and WB CORT change throughout ontogeny. We found that WB CORT is a valid method in pro-metamorphic larvae as values for both methods were highly correlated. In contrast, there was no correlation between tissue and WB CORT in newly hatched, pre-metamorphic larvae, metamorphs or post-metamorphic froglets probably due to ontogenetic changes in respiratory and skin morphology and physiology affecting the transdermal CORT release. Both collection methods consistently revealed a non-linear pattern of ontogenetic change in CORT with a peak at metamorphic climax. Thus, our results indicate that WB CORT sampling is a promising, non-invasive conservation tool for studies on late-stage amphibian larvae. However, we suggest considering that different contexts might affect the reliability of WB CORT and consequently urge future studies to validate this method whenever it is used in new approaches. We conclude proposing some recommendations and perspectives on the use of WB CORT that will aid in broadening its application as a non-invasive tool in amphibian conservation physiology.
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Affiliation(s)
- Katharina Ruthsatz
- Zoological Institute, Technische Universität Braunschweig, Mendelssohnstraße 4, 38106 Braunschweig, Germany
| | - Rafael Rico-Millan
- Ecology, Evolution, and Development Group, Doñana Biological Station – CSIC, Calle Américo Vespucio 26, 41092 Seville, Spain
| | - Paula Cabral Eterovick
- Zoological Institute, Technische Universität Braunschweig, Mendelssohnstraße 4, 38106 Braunschweig, Germany
| | - Ivan Gomez-Mestre
- Ecology, Evolution, and Development Group, Doñana Biological Station – CSIC, Calle Américo Vespucio 26, 41092 Seville, Spain
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4
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Rollins-Smith LA, Le Sage EH. Heat stress and amphibian immunity in a time of climate change. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220132. [PMID: 37305907 PMCID: PMC10258666 DOI: 10.1098/rstb.2022.0132] [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: 01/05/2023] [Accepted: 03/28/2023] [Indexed: 06/13/2023] Open
Abstract
As a class of vertebrates, amphibians, are at greater risk for declines or extinctions than any other vertebrate group, including birds and mammals. There are many threats, including habitat destruction, invasive species, overuse by humans, toxic chemicals and emerging diseases. Climate change which brings unpredictable temperature changes and rainfall constitutes an additional threat. Survival of amphibians depends on immune defences functioning well under these combined threats. Here, we review the current state of knowledge of how amphibians respond to some natural stressors, including heat and desiccation stress, and the limited studies of the immune defences under these stressful conditions. In general, the current studies suggest that desiccation and heat stress can activate the hypothalamus pituitary-interrenal axis, with possible suppression of some innate and lymphocyte-mediated responses. Elevated temperatures can alter microbial communities in amphibian skin and gut, resulting in possible dysbiosis that fosters reduced resistance to pathogens. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.
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Affiliation(s)
- Louise A. Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Emily H. Le Sage
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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5
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Madelaire CB, Silva DP, Titon SCM, Lamadrid-Feris F, Floreste FR, Titon Jr B, Gomes FR. Contrasting effects of transdermal and implant corticosterone treatments in the American bullfrog wound healing. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220119. [PMID: 37305919 PMCID: PMC10258662 DOI: 10.1098/rstb.2022.0119] [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: 10/28/2022] [Accepted: 02/13/2023] [Indexed: 06/13/2023] Open
Abstract
Glucocorticoid (GC) release is triggered by adverse stimuli that activate the hypothalamus-pituitary-adrenal/interrenal axis. Glucocorticoids may enhance or suppress immune functions depending on the level of elevation. In this study, we investigated the effects of transient and chronic increase of corticosterone (CORT) on the wound healing of the American bullfrog. Frogs were submitted to a daily transdermal hormonal application that acutely elevated CORT plasma levels, or vehicle as a control. Other frogs were surgically implanted with a silastic tube filled with CORT that resulted in chronic elevation of CORT plasma levels or received empty implants as a control. A dermal biopsy was performed to create a wound and was photographed every 3 days. Individuals treated with transdermal CORT started healing faster than their control 32 days after the biopsy. Frogs that received CORT implants tended to heal slower than control subjects. Plasma bacterial killing ability was not affected by treatment, which reinforces the constitutive nature of this innate immune trait. By the end of the experiment, frogs from the acute CORT treatment had smaller wounds compared with those receiving the CORT-filled implants, highlighting the differential effects of acute (immunoenhancing) and chronic (immunosuppressive) elevation of CORT plasma levels. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.
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Affiliation(s)
- Carla B. Madelaire
- Department of Physiology, University of Sao Paulo, Sao Paulo 05508-900, Brazil
- Beckman Center for Conservation Research, San Diego Zoo Wildlife Alliance Science, Escondido, CA 92027, USA
| | - Diego P. Silva
- Department of Physiology, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | | | | | - Felipe R. Floreste
- Department of Physiology, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Braz Titon Jr
- Department of Physiology, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Fernando R. Gomes
- Department of Physiology, University of Sao Paulo, Sao Paulo 05508-900, Brazil
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6
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Seebacher F, Narayan E, Rummer JL, Tomlinson S, Cooke SJ. How can physiology best contribute to wildlife conservation in a warming world? CONSERVATION PHYSIOLOGY 2023; 11:coad038. [PMID: 37287992 PMCID: PMC10243909 DOI: 10.1093/conphys/coad038] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 05/11/2023] [Accepted: 05/26/2023] [Indexed: 06/09/2023]
Abstract
Global warming is now predicted to exceed 1.5°C by 2033 and 2°C by the end of the 21st century. This level of warming and the associated environmental variability are already increasing pressure on natural and human systems. Here we emphasize the role of physiology in the light of the latest assessment of climate warming by the Intergovernmental Panel on Climate Change. We describe how physiology can contribute to contemporary conservation programmes. We focus on thermal responses of animals, but we acknowledge that the impacts of climate change are much broader phylogenetically and environmentally. A physiological contribution would encompass environmental monitoring, coupled with measuring individual sensitivities to temperature change and upscaling these to ecosystem level. The latest version of the widely accepted Conservation Standards designed by the Conservation Measures Partnership includes several explicit climate change considerations. We argue that physiology has a unique role to play in addressing these considerations. Moreover, physiology can be incorporated by institutions and organizations that range from international bodies to national governments and to local communities, and in doing so, it brings a mechanistic approach to conservation and the management of biological resources.
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Affiliation(s)
- Frank Seebacher
- School of Life and Environmental Sciences A08, University of Sydney, NSW 2006, Australia
| | - Edward Narayan
- School of Agriculture and Food Sciences, The University of Queensland, St. Lucia QLD4072, Australia
| | - Jodie L Rummer
- College of Science and Engineering and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville QLD 4810, Australia
| | - Sean Tomlinson
- School of Biological Sciences, University of Adelaide, SA 5000, Australia
| | - Steven J Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada
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7
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Lima AS, de Figueredo AC, Floreste FR, Garcia Neto PG, Gomes FR, Titon SCM. Temperature Extreme Events Decrease Endocrine and Immune Reactive Scope in Bullfrogs (Lithobates catesbeianus). Integr Comp Biol 2022; 62:1671-1682. [PMID: 35771987 DOI: 10.1093/icb/icac105] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 01/05/2023] Open
Abstract
Currently, effects of increased atmospheric temperature, in the context of ongoing climate change, have been investigated in multiple organisms and levels of biological organization. While there has been a focus on the impacts of increased mean temperature, an emergent and equally important point is the consequences of recurrent exposure to extreme temperature events, simulating heat waves. This study investigated the effects of serial exposure to high temperatures on immune and endocrine variables before and after exposure to an acute secondary stressor in bullfrogs (Lithobates catesbeianus). Adult males were divided into three groups and subjected to three thermal regimes: control (c; constant 22°C); experimental 1 (E1; kept at 22°C and exposed to 4 days of 30°C every 16 days); and experimental 2 (E2; kept at 22°C and exposed to 4 days of 30°C every 6 days). Blood samples were collected on the last day of key extreme heat events. Two weeks after the last extreme heat event, animals were subjected to restraint stress (1 h) and sampled again. Blood samples were used to determine neutrophil: lymphocyte ratio, plasma bacterial killing ability, as well as, corticosterone and plasma testosterone levels. Overall, we found exposure to extreme heat events did not affect immune and endocrine variables over time. Meanwhile, the previous exposure to extreme heat events modulated the responsiveness to restraint. The amplitude of increased corticosterone plasma levels and neutrophil: lymphocyte ratio in response to restraint decreased with the number of previous exposures to extreme heat events. These results suggest that exposure to extreme climatic events has hidden effects on bullfrog's stress response, expressed as diminished reactive scope to a novel stressor. This represents a highly deleterious facet of climate change since diminished responsiveness prevents proper coping with wildlife challenges.
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Affiliation(s)
- Alan Siqueira Lima
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Aymam Cobo de Figueredo
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Felipe Rangel Floreste
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Patrício Getúlio Garcia Neto
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Fernando Ribeiro Gomes
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Stefanny Christie Monteiro Titon
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
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8
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Dezetter M, Le Galliard JF, Leroux-Coyau M, Brischoux F, Angelier F, Lourdais O. Two stressors are worse than one: combined heatwave and drought affect hydration state and glucocorticoid levels in a temperate ectotherm. J Exp Biol 2022; 225:274818. [PMID: 35319758 DOI: 10.1242/jeb.243777] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 03/14/2022] [Indexed: 11/20/2022]
Abstract
Heatwaves and droughts are becoming more intense and frequent with climate change. These extreme weather events often occur simultaneously and may alter organismal physiology, yet their combined impacts remain largely unknown. Here, we experimentally investigated physiological responses of a temperate ectotherm, the asp viper (Vipera aspis), to a simulated heatwave and drought. We applied a two-by-two factorial design by manipulating the daily temperature cycle (control vs. heatwave) and the water availability (water available vs. water-deprived) over a month followed by exposure to standard thermal conditions with ad libium access to water. Simulated heatwave and water deprivation additively increased mass loss, while water deprivation led to greater plasma osmolality (dehydration). Mass gain from drinking after the treatment period was higher in vipers from the heatwave and water-deprived group suggesting that thirst was synergistically influenced by thermal and water constraints. Heatwave conditions and water deprivation also additively increased baseline corticosterone levels but did not influence basal metabolic rates and plasma markers of oxidative stress. Our results demonstrate that a short-term exposure to combined heatwave and drought can exacerbate physiological stress through additive effects, and interactively impact behavioral responses to dehydration. Considering combined effects of temperature and water availability is thus crucial to assess organismal responses to climate change.
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Affiliation(s)
- Mathias Dezetter
- Sorbonne University, CNRS, IRD, INRA, Institut d'écologie et des sciences de l'environnement (iEES Paris), 4 Place Jussieu, 75252 Paris Cedex 5, France.,Centre d'étude biologique de Chizé, UMR 7372 CNRS-La Rochelle Université, , 79360, Villiers en Bois, France
| | - Jean-François Le Galliard
- Sorbonne University, CNRS, IRD, INRA, Institut d'écologie et des sciences de l'environnement (iEES Paris), 4 Place Jussieu, 75252 Paris Cedex 5, France.,Ecole normale supérieure, PSL University, Département de biologie, CNRS, UMS 3194, Centre de recherche en écologie expérimentale et prédictive (CEREEP-Ecotron IleDeFrance), 11 chemin de Busseau, 77140 Saint-Pierre-lès-Nemours, France
| | - Mathieu Leroux-Coyau
- Sorbonne University, CNRS, IRD, INRA, Institut d'écologie et des sciences de l'environnement (iEES Paris), 4 Place Jussieu, 75252 Paris Cedex 5, France
| | - François Brischoux
- Centre d'étude biologique de Chizé, UMR 7372 CNRS-La Rochelle Université, , 79360, Villiers en Bois, France
| | - Fréderic Angelier
- Centre d'étude biologique de Chizé, UMR 7372 CNRS-La Rochelle Université, , 79360, Villiers en Bois, France
| | - Olivier Lourdais
- Centre d'étude biologique de Chizé, UMR 7372 CNRS-La Rochelle Université, , 79360, Villiers en Bois, France.,School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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9
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Forsburg ZR, Guzman A, Gabor CR. Artificial light at night (ALAN) affects the stress physiology but not the behavior or growth of Rana berlandieri and Bufo valliceps. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 277:116775. [PMID: 33639600 DOI: 10.1016/j.envpol.2021.116775] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 02/03/2021] [Accepted: 02/16/2021] [Indexed: 06/12/2023]
Abstract
Artificial light at night (ALAN) alters the natural light dark patterns in ecosystems. ALAN can have a suite of effects on community structure and is a driver of evolutionary processes that influences a range of behavioral and physiological traits. Our understanding of possible effects of ALAN across species amphibians is lacking and research is warranted as ALAN could contribute to stress and declines of amphibian populations, particularly in urban areas. We tested the hypothesis that exposure to constant light or pulsed ALAN would physiologically stress Rio Grande leopard frog (Rana berlandieri) and Gulf Coast toad (Bufo valliceps) tadpoles. We reared tadpoles under constant or pulsed (on and off again) ALAN for 14 days and measured corticosterone release rates over time using a non-invasive water-borne hormone protocol. ALAN treatments did not affect behavior or growth. Tadpoles of both species had higher corticosterone (cort) release rates after 14 days of constant light exposure. Leopard frog tadpoles had lower cort release rates after exposure to pulsed ALAN while toad tadpoles had higher cort release rates. These results suggest that short-term exposure to constant or pulsed light at night may contribute to stress in tadpoles but that each species differentially modulated their cort response to ALAN exposure and a subsequent stressor. This flexibility in the upregulation and downregulation of hypothalamic-pituitary-interrenal axis response may indicate an alternative mechanism for diminishing the deleterious effects of chronic stress. Nonetheless, ALAN should be considered in management and conservation plans for amphibians.
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Affiliation(s)
- Zachery R Forsburg
- Department of Biology, Texas State University, San Marcos, TX, 78666, USA.
| | - Alex Guzman
- Department of Biology, Texas State University, San Marcos, TX, 78666, USA
| | - Caitlin R Gabor
- Department of Biology, Texas State University, San Marcos, TX, 78666, USA
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10
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Lima AS, Ferreira LDF, Silva DP, Gomes FR, Titon SCM. Thermal sensitivity of Bullfrog's immune response kept at different temperatures. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 333:767-778. [PMID: 33369285 DOI: 10.1002/jez.2436] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 11/23/2020] [Accepted: 12/14/2020] [Indexed: 01/10/2023]
Abstract
Climate change and emerging infectious diseases are often described as the main factors associated with the worldwide amphibian population decline. In this context, rising temperatures due to global warming might act as a chronic stressor for many amphibians, leading to immunosuppression. This study aimed to characterize the thermal sensitivity of the Bullfrog's (Lithobates catesbeianus) immune response and the effect of acclimation at different temperatures on it. Plasma bacterial killing ability (BKA) and phagocytosis activity of blood leukocytes were measured at different incubation temperatures (5-40°C) in individuals kept at 28°C and 34°C. First, all individuals were held under 28°C and sampled on the 16th day. Subsequently, one group was kept at 28°, and the other one was transferred to 34°C. Both groups were sampled at 83 and 106 days of maintenance. Plasma corticosterone (CORT) and testosterone (T) were assessed to evidence thermal stress and possible endocrine correlates of immune changes over time. The incubation temperature affected BKA both on animals kept at 28°C and 34°C, with maximum values at lower temperatures (5-20°C). Phagocytosis activity was constant over the range of assay temperatures. Immune and endocrine variables decreased over time in both thermal regimes, but frogs maintained at 34°C showed lower T and immunosuppression, evidencing stress response. Therefore, exposure to high temperatures might decrease immune function in bullfrogs due to chronic stress response and by exposition to temperatures of lower performance according to the thermal sensitivity curve, which might increase vulnerability to diseases in this anuran species.
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Affiliation(s)
- Alan S Lima
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Letícia de F Ferreira
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Diego P Silva
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Fernando R Gomes
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Stefanny C M Titon
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
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11
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Laid-back invaders: Cane toads (Rhinella marina) down-regulate their stress responses as they colonize a harsh climate. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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12
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Abstract
AbstractEvolution of adaptation requires predictability and recurrence of functional contexts. Yet organisms live in multifaceted environments that are dynamic and ever changing, making it difficult to understand how complex adaptations evolve. This problem is particularly apparent in the evolution of adaptive maternal effects, which are often assumed to require reliable and discrete cues that predict conditions in the offspring environment. One resolution to this problem is if adaptive maternal effects evolve through preexisting, generalized maternal pathways that respond to many cues and also influence offspring development. Here, we assess whether an adaptive maternal effect in western bluebirds is influenced by maternal stress pathways across multiple challenging environments. Combining 18 years of hormone sampling across diverse environmental contexts with an experimental manipulation of the competitive environment, we show that multiple environmental factors influenced maternal corticosterone levels, which, in turn, influenced a maternal effect on aggression of sons in adulthood. Together, these results support the idea that multiple stressors can induce a known maternal effect in this system. More generally, they suggest that activation of general pathways, such as the hypothalamic-pituitary-adrenal axis, may simplify and facilitate the evolution of adaptive maternal effects by integrating variable environmental conditions into preexisting maternal physiological systems.
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13
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Rollins-Smith LA. Global Amphibian Declines, Disease, and the Ongoing Battle between Batrachochytrium Fungi and the Immune System. HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.178] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Louise A. Rollins-Smith
- Departments of Pathology, Microbiology and Immunology and Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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14
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Goff CB, Walls SC, Rodriguez D, Gabor CR. Changes in physiology and microbial diversity in larval ornate chorus frogs are associated with habitat quality. CONSERVATION PHYSIOLOGY 2020; 8:coaa047. [PMID: 32577287 PMCID: PMC7294888 DOI: 10.1093/conphys/coaa047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 04/29/2020] [Accepted: 05/08/2020] [Indexed: 06/11/2023]
Abstract
Environmental change associated with anthropogenic disturbance can lower habitat quality, especially for sensitive species such as many amphibians. Variation in environmental quality may affect an organism's physiological health and, ultimately, survival and fitness. Using multiple health measures can aid in identifying populations at increased risk of declines. Our objective was to measure environmental variables at multiple spatial scales and their effect on three indicators of health in ornate chorus frog (Pseudacris ornata) tadpoles to identify potential correlates of population declines. To accomplish this, we measured a glucocorticoid hormone (corticosterone; CORT) profile associated with the stress response, as well as the skin mucosal immune function (combined function of skin secretions and skin bacterial community) and bacterial communities of tadpoles from multiple ponds. We found that water quality characteristics associated with environmental variation, including higher water temperature, conductivity and total dissolved solids, as well as percent developed land nearby, were associated with elevated CORT release rates. However, mucosal immune function, although highly variable, was not significantly associated with water quality or environmental factors. Finally, we examined skin bacterial diversity as it aids in immunity and is affected by environmental variation. We found that skin bacterial diversity differed between ponds and was affected by land cover type, canopy cover and pond proximity. Our results indicate that both local water quality and land cover characteristics are important determinants of population health for ornate chorus frogs. Moreover, using these proactive measures of health over time may aid in early identification of at-risk populations that could prevent further declines and aid in management decisions.
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Affiliation(s)
- Cory B Goff
- Department of Biology, Texas State University, 601 University Dr.
San Marcos, TX 78666, USA
- Department of Biology and Chemistry, Liberty University, 1971
University Blvd. Lynchburg, VA 24515, USA
| | - Susan C Walls
- Wetland and Aquatic Research Center, U.S. Geological Survey, 7920
NW 71st St. Gainesville, FL 32653, USA
| | - David Rodriguez
- Department of Biology, Texas State University, 601 University Dr.
San Marcos, TX 78666, USA
| | - Caitlin R Gabor
- Department of Biology, Texas State University, 601 University Dr.
San Marcos, TX 78666, USA
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15
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Titon SCM, Titon B, Barsotti AMG, Gomes FR, Assis VR. Time-related immunomodulation by stressors and corticosterone transdermal application in toads. PLoS One 2019; 14:e0222856. [PMID: 31539413 PMCID: PMC6754171 DOI: 10.1371/journal.pone.0222856] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 09/09/2019] [Indexed: 12/22/2022] Open
Abstract
Immune responses have been mostly studied at a specific time in anuran species. However, time-changes related to immunomodulation associated with glucocorticoid (GC) alterations following stressors and GC treatment are complex. The present study describes time-related changes in immune response and corticosterone (CORT) plasma levels following restraint challenge, short, mid and long-term captivity, and CORT exogenous administration by transdermal application (TA) in Rhinella ornata toads. We observed increased neutrophil: lymphocyte ratios after restraint challenge and CORT TA, without changes following short and mid-term captivity. Plasma bacterial killing ability was sustained in all treatments, except long-term captivity, with decreased values after 90 days under such conditions. Phagocytic activity of peritoneal cells increased after mid-term captivity, and the phytohemagglutinin swelling response was impaired in those animals treated with CORT TA for 20 consecutive days. Plasma CORT levels increased or were sustained after restraint challenge (depending on initial values), decreased following mid and long-term captivity (for those animals showing high CORT in the field) and increased after 20 days of CORT TA. By performing assessments of time-changes in immune processes and CORT plasma levels in R. ornata, we demonstrate immuno-enhancing effects following restraint, short and mid-term stressors, while long-term stressors and CORT TA promoted immunosuppression in these toads.
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Affiliation(s)
| | - Braz Titon
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brasil
| | | | - Fernando Ribeiro Gomes
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Vania Regina Assis
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brasil
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16
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de Bruijn R, Romero LM. The role of glucocorticoids in the vertebrate response to weather. Gen Comp Endocrinol 2018; 269:11-32. [PMID: 30012539 DOI: 10.1016/j.ygcen.2018.07.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/29/2018] [Accepted: 07/13/2018] [Indexed: 12/18/2022]
Abstract
Changes in the environment related to inclement weather can threaten survival and reproductive success both through direct adverse exposure and indirectly by decreasing food availability. Glucocorticoids, released during activation of the hypothalamic-pituitary-adrenal axis as part of the stress response, are an important candidate for linking vertebrate coping mechanisms to weather. This review attempts to determine if there is a consensus response of glucocorticoids to exposure to weather-related stimuli, including food availability, precipitation, temperature and barometric pressure. The included studies cover field and laboratory studies for all vertebrate taxa, and are separated into four exposure periods, e.g., hours, days, weeks and months. Each reported result was assigned a score based on the glucocorticoid response, e.g., increased, no change, or decreased. Short-term exposure to weather-related stimuli, of up to 24 h, is generally associated with increased glucocorticoids (79% of studies), suggesting that these stimuli are perceived as stressors by most animals. In contrast, the pattern for exposures longer than 24 h shows more variation, even though a majority of studies still report an increase (64%). Lack of glucocorticoid increases appeared to result from instances where: (1) prolonged exposure was a predictable part of the life history of an animal; (2) environmental context was important for the ultimate effect of a stimulus (e.g., precipitation limited food availability in one environment, but increased food in another); (3) prolonged exposure induced chronic stress; and (4) long-term responses appeared to reflect adaptations to seasonal shifts, instead of to short-term weather. However, there is a strong bias towards studies in domesticated laboratory species and wild animals held in captivity, indicating a need for field studies, especially in reptiles and amphibians. In conclusion, the accumulated literature supports the hypothesis that glucocorticoids can serve as the physiological mechanism promoting fitness during inclement weather.
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Affiliation(s)
- Robert de Bruijn
- Department of Biology, Tufts University, Medford, MA 02155, USA.
| | - L Michael Romero
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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17
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Gastón MS, Pereyra LC, Vaira M. Artificial light at night and captivity induces differential effects on leukocyte profile, body condition, and erythrocyte size of a diurnal toad. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 331:93-102. [PMID: 30320969 DOI: 10.1002/jez.2240] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 09/11/2018] [Accepted: 09/19/2018] [Indexed: 01/27/2023]
Abstract
Light pollution or artificial lighting at night (ALAN) is an emerging threat to biodiversity that can disrupt physiological processes and behaviors. Because ALAN stressful effects are little studied in diurnal amphibian species, we investigated if chronic ALAN exposure affects the leukocyte profile, body condition, and blood cell sizes of a diurnal toad. We hand-captured male toads of Melanophryniscus rubriventris in Angosto de Jaire (Jujuy, Argentina). We prepared blood smears from three groups of toads: "field" (toads processed in the field immediately after capture), "natural light" (toads kept in the laboratory under captivity with natural photoperiod), and "constant light" (toads kept in the laboratory under captivity with constant photoperiod/ALAN). We significantly observed higher neutrophil proportions and neutrophils to lymphocytes ratio in toads under constant light treatment. In addition, we observed significantly better body condition and higher erythrocyte size in field toads compared with captive toads. In summary, ALAN can trigger a leukocyte response to stress in males of the diurnal toad M. rubriventris. In addition, captivity can affect the body condition and erythrocyte size of these toads.
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Affiliation(s)
- María S Gastón
- Instituto de Ecorregiones Andinas (INECOA), Universidad Nacional de Jujuy, CONICET, San Salvador de Jujuy, Argentina
| | - Laura C Pereyra
- Instituto de Ecorregiones Andinas (INECOA), Universidad Nacional de Jujuy, CONICET, San Salvador de Jujuy, Argentina
| | - Marcos Vaira
- Instituto de Ecorregiones Andinas (INECOA), Universidad Nacional de Jujuy, CONICET, San Salvador de Jujuy, Argentina
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18
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Novarro AJ, Gabor CR, Goff CB, Mezebish TD, Thompson LM, Grayson KL. Physiological responses to elevated temperature across the geographic range of a terrestrial salamander. J Exp Biol 2018; 221:jeb.178236. [DOI: 10.1242/jeb.178236] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 07/31/2018] [Indexed: 01/18/2023]
Abstract
Widespread species often possess physiological mechanisms for coping with thermal heterogeneity, and uncovering these mechanisms provides insight into species responses to climate change. The emergence of non-invasive corticosterone (CORT) assays allows us to rapidly assess physiological responses to environmental change on a large scale. We lack, however, a basic understanding of how temperature affects CORT, and whether temperature and CORT interactively affect performance. Here, we examine the effects of elevated temperature on CORT and whole-organism performance in a terrestrial salamander, Plethodon cinereus, across a latitudinal gradient. Using water-borne hormone assays, we found that raising ambient temperature from 15 to 25°C increased CORT release at a similar rate for salamanders from all sites. However, CORT release rate was higher overall in the warmest, southernmost site. Elevated temperatures also affected physiological performance, but the effects differed among sites. Ingestion rate increased in salamanders from the warmer sites but remained the same for those from cooler sites. Mass gain was reduced for most individuals, though this reduction was more dramatic in salamanders from the cooler sites. We also found a temperature-dependent relationship between CORT and food conversion efficiency (i.e., the amount of mass gained per unit food ingested). CORT was negatively related to food conversion efficiency at 25°C but was unrelated at 15°C. Thus, the energetic gains of elevated ingestion rates may be counteracted by elevated CORT release rates experienced by salamanders in warmer environments. By integrating multiple physiological metrics, we highlight the complex relationships between temperature and individual responses to warming climates.
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Affiliation(s)
| | - Caitlin R. Gabor
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Cory B. Goff
- Department of Biology, Texas State University, San Marcos, TX 78666, USA
| | - Tori D. Mezebish
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, USA
| | - Lily M. Thompson
- Department of Biology, University of Richmond, Richmond, VA 23173, USA
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19
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Cascading effects of thermally-induced anemone bleaching on associated anemonefish hormonal stress response and reproduction. Nat Commun 2017; 8:716. [PMID: 28993608 PMCID: PMC5634421 DOI: 10.1038/s41467-017-00565-w] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 07/10/2017] [Indexed: 12/30/2022] Open
Abstract
Organisms can behaviorally, physiologically, and morphologically adjust to environmental variation via integrative hormonal mechanisms, ultimately allowing animals to cope with environmental change. The stress response to environmental and social changes commonly promotes survival at the expense of reproduction. However, despite climate change impacts on population declines and diversity loss, few studies have attributed hormonal stress responses, or their regulatory effects, to climate change in the wild. Here, we report hormonal and fitness responses of individual wild fish to a recent large-scale sea warming event that caused widespread bleaching on coral reefs. This 14-month monitoring study shows a strong correlation between anemone bleaching (zooxanthellae loss), anemonefish stress response, and reproductive hormones that decreased fecundity by 73%. These findings suggest that hormone stress responses play a crucial role in changes to population demography following climate change and plasticity in hormonal responsiveness may be a key mechanism enabling individual acclimation to climate change.Elevated temperatures can cause anemones to bleach, with unknown effects on their associated symbiotic fish. Here, Beldade and colleagues show that climate-induced bleaching alters anemonefish hormonal stress response, resulting in decreased reproductive hormones and severely impacted reproduction.
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20
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Affiliation(s)
- Sarah K. Woodley
- Department of Biological Sciences, 600 Forbes Avenue, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
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21
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Claunch NM, Frazier JA, Escallón C, Vernasco BJ, Moore IT, Taylor EN. Physiological and behavioral effects of exogenous corticosterone in a free-ranging ectotherm. Gen Comp Endocrinol 2017; 248:87-96. [PMID: 28237812 DOI: 10.1016/j.ygcen.2017.02.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 01/11/2017] [Accepted: 02/17/2017] [Indexed: 10/20/2022]
Abstract
In the face of global change, free-ranging organisms are expected to experience more unpredictable stressors. An understanding of how organisms with different life history strategies will respond to such changes is an integral part of biodiversity conservation. Corticosterone (CORT) levels are often used as metrics to assess the population health of wild vertebrates, despite the fact that the stress response and its effects on organismal function are highly variable. Our understanding of the stress response is primarily derived from studies on endotherms, leading to some contention on the effects of chronic stress across and within taxa. We assessed the behavioral and hormonal responses to experimentally elevated stress hormone levels in a free-ranging, arid-adapted ectotherm, the Southern Pacific rattlesnake (Crotalus helleri). Plasma CORT was significantly elevated in CORT-implanted snakes 15days after implantation. Implantation with CORT did not affect testosterone (T) levels or defensive behavior. Interestingly, we observed increased defensive behavior in snakes with more stable daily body temperatures and in snakes with higher plasma T during handling (tubing). Regardless of treatment group, those individuals with lower baseline CORT levels and higher body temperatures tended to exhibit greater increases in CORT levels following a standardized stressor. These results suggest that CORT may not mediate physiological and behavioral trait expression in arid-adapted ectotherms such as rattlesnakes.
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Affiliation(s)
- Natalie M Claunch
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93401, USA.
| | - Julius A Frazier
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93401, USA
| | - Camilo Escallón
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Ben J Vernasco
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Ignacio T Moore
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Emily N Taylor
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93401, USA
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22
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Titon SCM, Assis VR, Titon Junior B, Cassettari BDO, Fernandes PACM, Gomes FR. Captivity effects on immune response and steroid plasma levels of a Brazilian toad (Rhinella schneideri). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:127-138. [DOI: 10.1002/jez.2078] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 04/30/2017] [Accepted: 06/11/2017] [Indexed: 02/05/2023]
Affiliation(s)
- Stefanny Christie Monteiro Titon
- Laboratório de Comportamento e Fisiologia Evolutiva; Departamento de Fisiologia, Instituto de Biociências; Universidade de São Paulo; São Paulo Brazil
| | - Vania Regina Assis
- Laboratório de Comportamento e Fisiologia Evolutiva; Departamento de Fisiologia, Instituto de Biociências; Universidade de São Paulo; São Paulo Brazil
| | - Braz Titon Junior
- Laboratório de Comportamento e Fisiologia Evolutiva; Departamento de Fisiologia, Instituto de Biociências; Universidade de São Paulo; São Paulo Brazil
| | - Bruna de Oliveira Cassettari
- Laboratório de Comportamento e Fisiologia Evolutiva; Departamento de Fisiologia, Instituto de Biociências; Universidade de São Paulo; São Paulo Brazil
| | - Pedro Augusto Carlos Magno Fernandes
- Laboratório de Comportamento e Fisiologia Evolutiva; Departamento de Fisiologia, Instituto de Biociências; Universidade de São Paulo; São Paulo Brazil
| | - Fernando Ribeiro Gomes
- Laboratório de Comportamento e Fisiologia Evolutiva; Departamento de Fisiologia, Instituto de Biociências; Universidade de São Paulo; São Paulo Brazil
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23
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High temperatures influence sexual development differentially in male and female tadpoles of the Indian skipper frog, Euphlyctis cyanophlyctis. J Biosci 2017; 42:449-457. [DOI: 10.1007/s12038-017-9689-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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24
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Mohammadi S, French SS, Neuman-Lee LA, Durham SL, Kojima Y, Mori A, Brodie ED, Savitzky AH. Corticosteroid responses of snakes to toxins from toads (bufadienolides) and plants (cardenolides) reflect differences in dietary specializations. Gen Comp Endocrinol 2017; 247:16-25. [PMID: 28347742 DOI: 10.1016/j.ygcen.2017.03.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 03/07/2017] [Accepted: 03/22/2017] [Indexed: 01/24/2023]
Abstract
Toads are chemically defended by cardiotonic steroids known as bufadienolides. Resistance to the acute effects of bufadienolides in snakes that prey on toads is conferred by target-site insensitivity of the toxin's target enzyme, the Na+/K+-ATPase. Previous studies have focused largely on the molecular mechanisms of resistance but have not investigated the physiological mechanisms or consequences of exposure to the toxins. Adrenal enlargement in snakes often is associated with specialization on a diet of toads. These endocrine glands are partly composed of interrenal tissue, which produces the corticosteroids corticosterone and aldosterone. Corticosterone is the main hormone released in response to stress in reptiles, and aldosterone plays an important role in maintaining ion balance through upregulation of Na+/K+-ATPase. We tested the endocrine response of select species of snakes to acute cardiotonic steroid exposure by measuring circulating aldosterone and corticosterone concentrations. We found that Rhabdophis tigrinus, which specializes on a diet of toads, responds with lower corticosterone and higher aldosterone compared to other species that exhibit target-site resistance to the toxins but do not specialize on toads. We also found differences between sexes in R. tigrinus, with males generally responding with higher corticosterone and aldosterone than females. This study provides evidence of physiological adaptations, beyond target-site resistance, associated with tolerance of bufadienolides in a specialized toad-eating snake.
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Affiliation(s)
- Shabnam Mohammadi
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States; Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT 84322-5205, United States.
| | - Susannah S French
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States; Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT 84322-5205, United States
| | - Lorin A Neuman-Lee
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States
| | - Susan L Durham
- Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT 84322-5205, United States
| | - Yosuke Kojima
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
| | - Akira Mori
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
| | - Edmund D Brodie
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States; Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT 84322-5205, United States
| | - Alan H Savitzky
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States; Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT 84322-5205, United States
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25
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Narayan EJ. Evaluation of physiological stress in Australian wildlife: Embracing pioneering and current knowledge as a guide to future research directions. Gen Comp Endocrinol 2017; 244:30-39. [PMID: 26686317 DOI: 10.1016/j.ygcen.2015.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 12/02/2015] [Accepted: 12/09/2015] [Indexed: 10/22/2022]
Abstract
Australia has a rich terrestrial and marine biodiversity and high species endemism. However, the oceanic continent is facing the biodiversity extinction crisis. The primary factors are anthropogenic induced environmental changes, including wildlife habitat destruction through urbanisation and predation by feral animals (e.g. red foxes and feral cats), increased severity of diseases (e.g. chytridiomycosis and chlamydia), and increased occurrence of summer heat waves and bush fires. Stress physiology is a dynamic field of science based on the studies of endocrine system functioning in animals. The primary stress regulator is the hypothalamo-pituitary adrenal (interrenal) axis and glucocorticoids (corticosterone and/or cortisol) provide stress index across vertebrate groups. This review paper focuses on physiological stress assessments in Australian wildlife using examples of amphibians, reptiles, birds and marsupials. I provide a thorough discussion of pioneering studies that have shaped the field of stress physiology in Australian wildlife species. The main findings point towards key aspects of stress endocrinology research, such as quantification of biologically active levels of glucocorticoids, development of species-specific GC assays and applications of stress physiology approaches in field ecology and wildlife conservation programs. Furthermore, I also discuss the importance of chronic stress assessment in wildlife populations. Finally, I provide a conceptual framework presenting key research questions in areas of wildlife stress physiology research. In conclusion, wildlife management programs can immensely benefit from stress physiology assessments to gauge the impact of human interventions on wildlife such as species translocation and feral species eradication.
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Affiliation(s)
- Edward J Narayan
- Graham Centre for Agricultural Innovation & School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
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26
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ACTH modulation on corticosterone, melatonin, testosterone and innate immune response in the tree frog Hypsiboas faber. Comp Biochem Physiol A Mol Integr Physiol 2016; 204:177-184. [PMID: 27923708 DOI: 10.1016/j.cbpa.2016.12.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 11/30/2016] [Accepted: 12/01/2016] [Indexed: 11/21/2022]
Abstract
The modulation exerted by glucocorticoids in physiological responses to stressors is essential for maintaining short-term homeostasis. However, highly frequent and/or prolonged activation of the hypothalamic-pituitary-adrenal/interrenal axis may inhibit processes that are important to long-term fitness and health, including reproduction and immunocompetence. The present study evaluates the response to adrenocorticotropic hormone (ACTH) injection in the adult male tree frog, Hypsiboas faber, as indicated by levels of plasma corticosterone (CORT), plasma testosterone (T), ocular melatonin (MEL), hematocrit and immune functioning (total leukocyte count and bacterial killing ability against Escherichia coli). All levels were measured 1, 3 and 6h after treatment. ACTH increased CORT levels whilst decreasing T and MEL levels at 1h post-treatment. 6h after ACTH injection, hematocrit and MEL levels increased. ACTH treatment did not significantly modulate the immune measures over the time-range sampled. The hormonal changes observed in response to ACTH treatment suggest that stressors could act as inhibitors of reproductive activity, as well as differentially modulating melatonin levels at different time-points.
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27
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Hing S, Narayan EJ, Thompson RCA, Godfrey SS. The relationship between physiological stress and wildlife disease: consequences for health and conservation. WILDLIFE RESEARCH 2016. [DOI: 10.1071/wr15183] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Wildlife populations are under increasing pressure from a variety of threatening processes, ranging from climate change to habitat loss, that can incite a physiological stress response. The stress response influences immune function, with potential consequences for patterns of infection and transmission of disease among and within wildlife, domesticated animals and humans. This is concerning because stress may exacerbate the impact of disease on species vulnerable to extinction, with consequences for biodiversity conservation globally. Furthermore, stress may shape the role of wildlife in the spread of emerging infectious diseases (EID) such as Hendra virus (HeV) and Ebola virus. However, we still have a limited understanding of the influence of physiological stress on infectious disease in wildlife. We highlight key reasons why an improved understanding of the relationship between stress and wildlife disease could benefit conservation, and animal and public health, and discuss approaches for future investigation. In particular, we recommend that increased attention be given to the influence of anthropogenic stressors including climate change, habitat loss and management interventions on disease dynamics in wildlife populations.
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28
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Narayan EJ, Gramapurohit NP. Sexual dimorphism in baseline urinary corticosterone metabolites and their association with body-condition indices in a peri-urban population of the common Asian toad (Duttaphrynus melanostictus). Comp Biochem Physiol A Mol Integr Physiol 2015; 191:174-179. [PMID: 26478192 DOI: 10.1016/j.cbpa.2015.10.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 10/02/2015] [Accepted: 10/11/2015] [Indexed: 11/29/2022]
Abstract
Field endocrinology research through the quantification of glucocorticoids or stress hormones in free-living wildlife is crucial for assessing their physiological responses towards pervasive environmental changes. Urinary corticosterone metabolite (UCM) enzyme-immunoassay (EIA) has been validated for numerous amphibian species as a non-invasive measure of physiological stress. Body-condition indices (BCIs) have also been widely used in amphibians as an indirect measure of animal health. Field endocrinology research on amphibian species in Asia is limited. In this study, we validated a UCM EIA in a peri-urban sub-population of the common Asian toad (Duttaphrynus melanostictus) in Pune, Maharashtra, India. We determined the baseline levels of UCMs in male (n=39) and female (n=19) toads. Secondly, we used a standard capture handling protocol to quantify changes in UCMs during short-term captivity. We also determined BCIs in the male and female toads using Fulton's index (K) and residual condition index (RCI). The results showed that mean baseline levels of UCMs were significantly higher in male toads than in females. There was no significant change in mean levels of UCMs of males and females between capture and captivity (0-12h). This highlights plausible habituation of the species to the peri-urban environment. Associations between UCMs with BCIs (K and R) were positive in male toads but negative in females. In conclusion, our UCMs EIA can be applied with BCIs to assess health of the Asian toads. We also suggest that direct fitness parameters such as sperm and oocyte quality, reproductive ecology and immunocompetence measurements should be applied in combination with these conservation physiology tools to quantify the fitness consequences of pervasive environmental changes on native amphibians.
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Affiliation(s)
- Edward J Narayan
- School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
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29
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Gao X, Jin C, Camargo A, Li Y. Allocation trade-off under climate warming in experimental amphibian populations. PeerJ 2015; 3:e1326. [PMID: 26500832 PMCID: PMC4614843 DOI: 10.7717/peerj.1326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 09/24/2015] [Indexed: 11/24/2022] Open
Abstract
Climate change could either directly or indirectly cause population declines via altered temperature, rainfall regimes, food availability or phenological responses. However few studies have focused on allocation trade-offs between growth and reproduction under marginal resources, such as food scarce that may be caused by climate warming. Such critical changes may have an unpredicted impact on amphibian life-history parameters and even population dynamics. Here, we report an allocation strategy of adult anuran individuals involving a reproductive stage under experimental warming. Using outdoor mesocosm experiments we simulated a warming scenario likely to occur at the end of this century. We examined the effects of temperature (ambient vs. pre-/post-hibernation warming) and food availability (normal vs. low) on reproduction and growth parameters of pond frogs (Pelophylax nigromaculatus). We found that temperature was the major factor influencing reproductive time of female pond frogs, which showed a significant advancing under post-hibernation warming treatment. While feeding rate was the major factor influencing reproductive status of females, clutch size, and variation of body size for females, showed significant positive correlations between feeding rate and reproductive status, clutch size, or variation of body size. Our results suggested that reproduction and body size of amphibians might be modulated by climate warming or food availability variation. We believe this study provides some new evidence on allocation strategies suggesting that amphibians could adjust their reproductive output to cope with climate warming.
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Affiliation(s)
- Xu Gao
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences , Beijing , China ; University of Chinese Academy of Sciences , Beijing , China
| | - Changnan Jin
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences , Beijing , China ; University of Chinese Academy of Sciences , Beijing , China ; Chinese National Geography Magazine , Beijing , China
| | - Arley Camargo
- Centro Universitario de Rivera, Universidad de la República , Rivera , Uruguay
| | - Yiming Li
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences , Beijing , China
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Ashton DT, Bettaso JB, Welsh HH. Changes across a Decade in Size, Growth, and Body Condition of Western Pond Turtle (Actinemys marmorata) Populations on Free-flowing and Regulated Forks of the Trinity River in Northwest California. COPEIA 2015. [DOI: 10.1643/cp-15-253] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Effects of acute restraint stress, prolonged captivity stress and transdermal corticosterone application on immunocompetence and plasma levels of corticosterone on the cururu Toad (Rhinella icterica). PLoS One 2015; 10:e0121005. [PMID: 25831055 PMCID: PMC4382218 DOI: 10.1371/journal.pone.0121005] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 02/09/2015] [Indexed: 11/19/2022] Open
Abstract
Glucocorticoid steroids modulate immunocompetence in complex ways with both immunoenhancing and immunosuppressive effects in vertebrates exposed to different stressors. Such bimodal effects have been associated with variation in duration and intensity of the stress response. Given that natural populations have been exposed to a multitude of stressors, a better understanding of the functional association between duration and intensity of the stress response, the resulting changes in glucocorticoid plasma levels and their impact on different aspects of immunocompetence emerges as a cornerstone for vertebrate conservation strategies. We investigated the effects of a restraint challenge (with and without movement restriction), long-term captivity, and transdermal corticosterone application on plasma levels of corticosterone (hereinafter referred to as CORT) and different parameters of innate immunocompetence in the male cururu toads (Rhinella icterica). We show that for R. icterica restraint for 24h proved to be a stressful condition, increasing CORT by 3-fold without consistent immunological changes. However, the application of a more intense stressor (restraint with movement restriction), for the same period, potentiated this response resulting in a 9-fold increase in CORT, associated with increase Neutrophil/Lymphocyte ratio (N:L) and a lower bacterial killing ability (BKA). Transdermal application of corticosterone efficiently mimics repeated acute stress response events, without changing the immune parameters even after 13 days of treatment. Interestingly, long-term captivity did not mitigate the stress response, since the toads maintained 3-fold increased CORT even after 3 months under these conditions. Moreover, long-term captivity in the same condition increased total leukocyte count (TLC) and generated an even greater decrease in BKA, suggesting that consequences of the stress response can be aggravated by time in captivity.
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Hing S, Narayan E, Thompson RCA, Godfrey S. A review of factors influencing the stress response in Australian marsupials. CONSERVATION PHYSIOLOGY 2014; 2:cou027. [PMID: 27293648 PMCID: PMC4732483 DOI: 10.1093/conphys/cou027] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Revised: 05/16/2014] [Accepted: 06/02/2014] [Indexed: 05/29/2023]
Abstract
Many Australian marsupials are threatened species. In order to manage in situ and ex situ populations effectively, it is important to understand how marsupials respond to threats. Stress physiology (the study of the response of animals to challenging stimuli), a key approach in conservation physiology, can be used to characterize the physiological response of wildlife to threats. We reviewed the literature on the measurement of glucocorticoids (GCs), endocrine indicators of stress, in order to understand the stress response to conservation-relevant stressors in Australian marsupials and identified 29 studies. These studies employed a range of methods to measure GCs, with faecal glucocorticoid metabolite enzyme immunoassay being the most common method. The main stressors considered in studies of marsupials were capture and handling. To date, the benefits of stress physiology have yet to be harnessed fully in marsupial conservation. Despite a theoretical base dating back to the 1960s, GCs have only been used to understand how 21 of the 142 extant species of Australian marsupial respond to stressors. These studies include merely six of the 60 marsupial species of conservation concern (IUCN Near Threatened to Critically Endangered). Furthermore, the fitness consequences of stress for Australian marsupials are rarely examined. Individual and species differences in the physiological stress response also require further investigation, because significant species-specific variations in GC levels in response to stressors can shed light on why some individuals or species are more vulnerable to stress factors while others appear more resilient. This review summarizes trends, knowledge gaps and future research directions for stress physiology research in Australian marsupial conservation.
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Affiliation(s)
- Stephanie Hing
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - Edward Narayan
- Environmental Futures Research Institute, Griffith School of Environment, Griffith University, Southport, QLD 4222, Australia
| | - R. C. Andrew Thompson
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia
| | - Stephanie Godfrey
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia
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Narayan EJ, Evans N, Hero JM. Monitoring physiological stress in semi-free ranging populations of an endangered Australian marsupial, the Greater Bilby (Macrotis lagotis). EUR J WILDLIFE RES 2014. [DOI: 10.1007/s10344-014-0842-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Narayan EJ, Hero JM. Acute thermal stressor increases glucocorticoid response but minimizes testosterone and locomotor performance in the cane toad (Rhinella marina). PLoS One 2014; 9:e92090. [PMID: 24643017 PMCID: PMC3958476 DOI: 10.1371/journal.pone.0092090] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 02/19/2014] [Indexed: 11/18/2022] Open
Abstract
Climatic warming is a global problem and acute thermal stressor in particular could be considered as a major stressor for wildlife. Cane toads (Rhinella marina) have expanded their range into warmer regions of Australia and they provide a suitable model species to study the sub-lethal impacts of thermal stressor on the endocrine physiology of amphibians. Presently, there is no information to show that exposure to an acute thermal stressor could initiate a physiological stress (glucocorticoid) response and secondly, the possible effects on reproductive hormones and performance. Answering these questions is important for understanding the impacts of extreme temperature on amphibians. In this study, we experimented on cane toads from Queensland, Australia by acclimating them to mildly warm temperature (25°C) and then exposing to acute temperature treatments of 30°, 35° or 40°C (hypothetical acute thermal stressors). We measured acute changes in the stress hormone corticosterone and the reproductive hormone testosterone using standard capture and handling protocol and quantified the metabolites of both hormones non-invasively using urinary enzyme-immunoassays. Furthermore, we measured performance trait (i.e. righting response score) in the control acclimated and the three treatment groups. Corticosterone stress responses increased in all toads during exposure to an acute thermal stressor. Furthermore, exposure to a thermal stressor also decreased testosterone levels in all toads. The duration of the righting response (seconds) was longer for toads that were exposed to 40°C than to 30°, 35° or 25°C. The increased corticosterone stress response with increased intensity of the acute thermal stressor suggests that the toads perceived this treatment as a stressor. Furthermore, the results also highlight a potential trade-off with performance and reproductive hormones. Ultimately, exposure acute thermal stressors due to climatic variability could impact amphibians at multiple eco-physiological levels through impacts on endocrine physiology, performance and potentially fitness traits (e.g. reproductive output).
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Affiliation(s)
- Edward J Narayan
- Environmental Futures Research Institute, School of Environment, Griffith University, Gold Coast Campus, Australia
| | - Jean-Marc Hero
- Environmental Futures Research Institute, School of Environment, Griffith University, Gold Coast Campus, Australia
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