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O'Dwyer K, Milotic D, Milotic M, Koprivnikar J. Behave yourself: effects of exogenous-glucocorticoid exposure on larval amphibian anti-parasite behaviour and physiology. Oecologia 2024:10.1007/s00442-024-05547-6. [PMID: 38689180 DOI: 10.1007/s00442-024-05547-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 03/30/2024] [Indexed: 05/02/2024]
Abstract
Parasites represent a ubiquitous threat for most organisms, requiring potential hosts to invest in a range of strategies to defend against infection-these include both behavioural and physiological mechanisms. Avoidance is an essential first line of defence, but this behaviour may show a trade-off with host investment in physiological immunity. Importantly, while environmental stressors can lead to elevated hormones in vertebrates, such as glucocorticoids, that can reduce physiological immunity in certain contexts, behavioural defences may also be compromised. Here, we investigate anti-parasite behaviour and immune responses against a trematode (flatworm) parasite by larval amphibians (tadpoles) exposed or not to a simulated general stressor in the form of exogenous corticosterone. Tadpoles that were highly active in the presence of the trematode infectious stage (cercariae) had lower infection loads, and parasite loads from tadpoles treated only with dechlorinated water were significantly lower than those exposed to corticosterone or the solvent control. However, treatment did not affect immunity as measured through white blood-cell profiles, and there was no relationship between the latter and anti-parasite behaviour. Our results suggest that a broad range of stressors could increase host susceptibility to infection through altered anti-parasite behaviours if they elevate endogenous glucocorticoids, irrespective of physiological immunity effects. How hosts defend themselves against parasitism in the context of multiple challenges represents an important topic for future research, particularly as the risk posed by infectious diseases is predicted to increase in response to ongoing environmental change.
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Affiliation(s)
- Katie O'Dwyer
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON, Canada.
- Marine and Freshwater Research Centre, Atlantic Technological University, Old Dublin Road, Co., Galway, Ireland.
| | - Dino Milotic
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON, Canada
- Harry Butler Institute, Murdoch University, Perth, WA, Australia
| | - Marin Milotic
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON, Canada
- Harry Butler Institute, Murdoch University, Perth, WA, Australia
| | - Janet Koprivnikar
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON, Canada
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2
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Assis VR, Titon SCM, Titon B, Gomes FR. The Impacts of Transdermal Application of Corticosterone on Toad (Rhinella icterica) Immunity. Integr Comp Biol 2022; 62:1640-1653. [PMID: 35902322 DOI: 10.1093/icb/icac130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/23/2022] [Accepted: 07/24/2022] [Indexed: 01/05/2023] Open
Abstract
Recent studies have shown that acute physiological increases in endogenous glucocorticoid levels have immunostimulatory effects. Although post-acute stress immunosuppressive effects have also been described, the difference between enhancing and suppressing the immune response seems mediated by the stressor's duration, intensity, and the immune component under analysis. To elicit physiologically relevant corticosterone levels that can be found in Rhinella icterica toads after stressful events (e.g., restraint or captivity) and understand how acute increased glucocorticoid levels of different intensities affect corticosterone and testosterone plasma levels and immune parameters (in vitro plasma bacterial killing ability, neutrophil-to-lymphocyte ratio, and in vivo phagocytosis of peritoneal leukocytes), we submitted toads to the transdermal application of two corticosterone doses (1 and 10 μg). Corticosterone transdermal application increased corticosterone plasma levels with different intensities: 3 times for 1 μg and fourteen times for 10 μg, compared to the vehicle, and the neutrophil-to-lymphocyte ratio increased regardless of the corticosterone dose. However, there was no effect on testosterone levels and bacterial killing ability. Interestingly, both corticosterone doses promoted immunosuppression, decreasing peritoneal leukocytes' phagocytosis activity by 60% for toads receiving the dose of 1µg and 40% for those receiving 10 μg. Our results show the complexity of the relationship between increased corticosterone levels and immunomodulation. The different corticosterone doses promoted increases of distinct magnitudes in corticosterone plasma levels, with the less intense increase in corticosterone levels generating greater cell-mediated immunosuppression. Future studies using different corticosterone doses to achieve and compare physiological vs. pharmacological hormone levels are imperative to understanding these interrelationships between corticosterone and immune response.
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Affiliation(s)
- Vania Regina Assis
- 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
| | - Braz Titon
- 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
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3
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Durso AM, Smith GD, Hudson SB, French SS. Stoichiometric and stable isotope ratios of wild lizards in an urban landscape vary with reproduction, physiology, space and time. Conserv Physiol 2020; 8:coaa001. [PMID: 32082575 PMCID: PMC7019090 DOI: 10.1093/conphys/coaa001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/13/2019] [Accepted: 01/08/2020] [Indexed: 06/10/2023]
Abstract
Spatial and temporal variation in stoichiometric and stable isotope ratios of animals contains ecological information that we are just beginning to understand. In both field and lab studies, stoichiometric or isotopic ratios are related to physiological mechanisms underlying nutrition or stress. Conservation and ecosystem ecology may be informed by isotopic data that can be rapidly and non-lethally collected from wild animals, especially where human activity leaves an isotopic signature (e.g. via introduction of chemical fertilizers, ornamental or other non-native plants or organic detritus). We examined spatial and temporal variation in stoichiometric and stable isotope ratios of the toes of Uta stansburiana (side-blotched lizards) living in urban and rural areas in and around St. George, Utah. We found substantial spatial and temporal variation as well as context-dependent co-variation with reproductive physiological parameters, although certain key predictions such as the relationship between δ15N and body condition were not supported. We suggest that landscape change through urbanization can have profound effects on wild animal physiology and that stoichiometric and stable isotope ratios can provide unique insights into the mechanisms underlying these processes.
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Affiliation(s)
- Andrew M Durso
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan UT 84321 USA
- Department of Biological Sciences, Florida Gulf Coast University, 10501 FGCU Blvd S, Fort Myers, FL 33965 USA
| | - Geoffrey D Smith
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan UT 84321 USA
- Biological Sciences Department, Dixie State University, 225 S. University Avenue, St. George, UT 84770 USA
| | - Spencer B Hudson
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan UT 84321 USA
| | - Susannah S French
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan UT 84321 USA
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Neuman-Lee LA, Hudson SB, Webb AC, French SS. Investigating the relationship between corticosterone and glucose in a reptile. ACTA ACUST UNITED AC 2020; 223:jeb.203885. [PMID: 31767736 DOI: 10.1242/jeb.203885] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 11/19/2019] [Indexed: 12/20/2022]
Abstract
The glucocorticoid hormone corticosterone (CORT) has classically been used in ecophysiological studies as a proxy for stress and energy mobilization, but rarely are CORT and the energy metabolites themselves concurrently measured. To examine CORT's role in mobilizing glucose in a wild reptile, we conducted two studies. The first study measured natural baseline and stress-induced blood-borne CORT and glucose levels in snakes during spring emergence and again when snakes return to the denning sites in autumn. The second study manipulated the hypothalamic-pituitary-adrenal (HPA) axis in male snakes in the autumn by taking a baseline blood sample, then subjecting individuals to one of five treatments (no injection, saline, CORT, adrenocorticotropin hormone and metyrapone). Subsequent samples were taken at 30 and 60 min. In both studies, we found that glucose levels do increase with acute stress, but that the relationship was not directly related to CORT elevation. In the second study, we found that none of the HPA axis manipulations directly affected blood glucose levels, further indicating that CORT may play a complex but not direct role in glucose mobilization in snakes. This study highlights the need for testing mechanisms in wild organisms by combining in situ observations with manipulative studies.
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Affiliation(s)
- Lorin A Neuman-Lee
- Department of Biological Sciences, Arkansas State University, Jonesboro, AR 72401, USA
| | - Spencer B Hudson
- Department of Biology, Utah State University, Logan, UT 84322, USA
| | - Alison C Webb
- Department of Biology, Utah State University, Logan, UT 84322, USA
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Hart SL, Spicer MM, Wrynn T, Chapman TL, Spivey KL, Gall BG. Palatability and Predator Avoidance Behavior of Salamanders in Response to the Virginia Opossum (Didelphis Virginiana). The American Midland Naturalist 2019; 181:245. [DOI: 10.1674/0003-0031-181.2.245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Lawrence MJ, Godin JGJ, Zolderdo AJ, Cooke SJ. Chronic Plasma Cortisol Elevation Does Not Promote Riskier Behavior in a Teleost Fish: A Test of the Behavioral Resiliency Hypothesis. Integr Org Biol 2019; 1:obz009. [PMID: 33791525 PMCID: PMC7671160 DOI: 10.1093/iob/obz009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Stressed fish have been shown to have higher predator-induced mortality than unstressed conspecifics, suggesting a role for the hypothalamic-pituitary-interrenal axis in modifying risk-taking behaviors. Yet, there is also evidence of behavioral resiliency in the face of chronic stressors. Here, we tested the behavioral resiliency hypothesis, which posits that animals can maintain consistent behavioral phenotypes in the face of significant physiological challenges. We determined whether chronic plasma cortisol elevation promotes risk-taking behaviors in a model teleost fish, the pumpkinseed sunfish (Lepomis gibbosus). Experimental fish were implanted with cocoa butter either as a sham or with cortisol. At 48 h post-implantation, the behavior of individual focal fish was tested in an experimental arena comprising of a simulated physical refuge, an open zone containing a constrained conspecific shoal, and a compartment containing either a model of a northern pike (Esox lucius) paired with corresponding pike olfactory cues in lake water or no pike model (control) paired with sham lake water cues only. The fish were assayed individually for their refuge utilization, shoaling tendency, and general activity. Neither cortisol treatment nor predation-risk treatment influenced any of these behaviors. This suggests that sunfish, in the context of our experiment, were behaviorally resilient to the physiological effects of chronic plasma cortisol elevation and in the face of an apparent threat of predation. Our results thus provide support for the behavioral resiliency hypothesis in fish under both physiological and ecological stressors. We posit that behavioral resiliency is an evolutionary adaptation ensuring appropriate responses to environmental conditions.
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Affiliation(s)
- Michael J Lawrence
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6.,Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6
| | - Jean-Guy J Godin
- Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6
| | - Aaron J Zolderdo
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6.,Queen's University Biological Station, Queen's University, Elgin, Ontario, Canada K0G 1E0
| | - Steven J Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6
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Weaver M, Gao S, McGraw KJ. Circulating corticosterone levels vary during exposure to anthropogenic stimuli and show weak correlation with behavior across an urban gradient in house finches (Haemorhous mexicanus). Gen Comp Endocrinol 2018; 266:52-59. [PMID: 29673843 DOI: 10.1016/j.ygcen.2018.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 04/08/2018] [Accepted: 04/14/2018] [Indexed: 01/08/2023]
Abstract
Urban environments are rapidly expanding and presenting animal populations with novel challenges, many of which are thought to be stressors that contribute to low biodiversity. However, studies on stress responses in urban vs rural populations have produced mixed results, and many of these studies use a standard stressor that cannot be replicated in the wild (e.g. restraining an animal in a bag). Pairing physiological and behavioral measurements in response to urban-related stressors improves our understanding of the mechanism underlying animal success in human-dominated landscapes. Here, we examined the physiological stress (plasma corticosterone, CORT) responses of a songbird species (the house finch, Haemorhous mexicanus) to two different anthropogenic stimuli - (1) the presence of a human and (2) a captive environment containing man-made objects. During three field seasons (summer 2012, winter 2014, and winter 2015), we captured birds at six sites along an urban gradient in Phoenix, Arizona, USA and measured plasma CORT levels both before and after each trial. Though CORT levels did increase post-human exposure, though not during exposure to novel environment, indicating only one of the treatments caused a physiological response, baseline or post-trial plasma CORT levels did not differ between finches between urban and rural birds in 2012 or 2014. However, rural birds demonstrated relatively low pre- and post-trial plasma CORT levels during the human-exposure trials in 2015. Furthermore, we found few correlations between behavioral and physiological responses. A significant positive correlation was only detected between activity behavior after human approach and post-trial plasma CORT levels in 2012. Taken together, our results reveal a weak, conditional relationship between stress physiology, behavioral responses, and urbanization in house finches.
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Affiliation(s)
- Melinda Weaver
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, United States.
| | - Sisi Gao
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, United States
| | - Kevin J McGraw
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, United States
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Iglesias-Carrasco M, Head ML, Cabido C. Effect of an immune challenge on the anti-predator response of the green Iberian frog (Pelophylax perezi): the influence of urban habitats. Biol J Linn Soc Lond 2018. [DOI: 10.1093/biolinnean/bly051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Maider Iglesias-Carrasco
- Department of Evolutionay Ecology, Museo Nacional de Ciencias Naturales (MNCN-CSIC). José Madrid, Spain
- Department of Herpetology, Aranzadi Science Society. Zorroagagaina, Donostia-San Sebastián, Gipuzkoa, Spain
| | - Megan L Head
- Division of Evolution, Ecology and Genetics. Australian National University. Research School of Biology, Linnaeus Way, Acton ACT 2601. Canberra, Australia
| | - Carlos Cabido
- Department of Herpetology, Aranzadi Science Society. Zorroagagaina, Donostia-San Sebastián, Gipuzkoa, Spain
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9
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Gabor CR, Knutie SA, Roznik EA, Rohr JR. Are the adverse effects of stressors on amphibians mediated by their effects on stress hormones? Oecologia 2018; 186:393-404. [DOI: 10.1007/s00442-017-4020-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 11/22/2017] [Indexed: 11/25/2022]
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Affiliation(s)
- Andrew M. Durso
- Department of Biology & The Ecology Center Utah State University Logan UT USA
| | - Susannah S. French
- Department of Biology & The Ecology Center Utah State University Logan UT USA
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11
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Neuman-Lee LA, Brodie ED, Hansen T, Brodie ED, French SS. To stress or not to stress: Physiological responses to tetrodotoxin in resistant gartersnakes vary by sex. Comp Biochem Physiol A Mol Integr Physiol 2017; 209:34-40. [DOI: 10.1016/j.cbpa.2015.11.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/10/2015] [Accepted: 11/05/2015] [Indexed: 01/08/2023]
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12
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Neuman-Lee L, Greives T, Hopkins GR, French SS. The role of the kisspeptin system in regulation of the reproductive endocrine axis and territorial behavior in male side-blotched lizards (Uta stansburiana). Horm Behav 2017; 89:48-54. [PMID: 28017596 DOI: 10.1016/j.yhbeh.2016.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/23/2016] [Accepted: 12/12/2016] [Indexed: 11/18/2022]
Abstract
The neuropeptide kisspeptin and its receptor are essential for activation of the hypothalamic-pituitary-gonadal (HPG) axis and regulating reproduction. While the role of kisspeptin in regulating the HPG axis in mammals has been well established, little is known about the functional ability of kisspeptins to activate the HPG axis and associated behavior in non-mammalian species. Here we experimentally examined the effects of kisspeptin on downstream release of testosterone and associated aggression and display behaviors in the side-blotched lizard (Uta stansburiana). We found that exogenous treatment with kisspeptin resulted in an increase in circulating testosterone levels, castration blocked the kisspeptin-induced increase in testosterone, and testosterone levels in kisspeptin-treated animals were positively related to frequency of aggressive behaviors. This evidence provides a clear link between kisspeptin, testosterone, and aggressive behavior in lizards. Thus, it is likely that kisspeptin plays an important role more broadly in non-mammalian systems in the regulation of reproductive physiology and related behaviors.
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Affiliation(s)
- Lorin Neuman-Lee
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, USA
| | - Timothy Greives
- Department of Biological Sciences, North Dakota State University, Fargo, ND 58106, USA
| | - Gareth R Hopkins
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, USA
| | - Susannah S French
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, USA; The Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT 84322-5205, USA.
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13
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Herr MW, Graham SP, Langkilde T. Stressed snakes strike first: Hormone levels and defensive behavior in free ranging cottonmouths (Agkistrodon piscivorus). Gen Comp Endocrinol 2017; 243:89-95. [PMID: 27823955 DOI: 10.1016/j.ygcen.2016.11.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 10/29/2016] [Accepted: 11/03/2016] [Indexed: 01/02/2023]
Abstract
Stress is believed to be an important factor mediating animal behavior. Here we explore the relationship between concentrations of a stress hormone and defensive behavior of a snake. The cottonmouth (Agkistrodon piscivorus) is an abundant, large-bodied pitviper that is well known for its intense defensive behaviors. The defensive behaviors and hormonal ecology of cottonmouths have been studied extensively, but the interaction between these is not well understood. We conducted field trials, recording the snake's behavior and obtaining blood samples to quantify plasma CORT concentrations, both upon first encountering a snake and after a 30min standardized confinement stressor. We found that snakes with elevated levels of baseline CORT at first encounter were more likely to strike than exhibit a threat display when approached in the field. However, this behavior was not related to the magnitude of the snake's CORT increase following confinement, suggesting that more stress-prone snakes are not more defensive. Post-stressor antipredator behavior was also not related to any of our CORT measures. This study suggests that baseline CORT levels can be important correlates of defensive behavior. If this is a causative relationship, environmental challenges that increase baseline stress levels of populations may elevate cottonmouth defensive behavior. This would increase costs associated with defensive behavior (energetic, lost opportunity, etc.) and have important consequences for animal-human interactions.
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Affiliation(s)
- Mark W Herr
- Department of Biology, The Pennsylvania State University, USA.
| | - Sean P Graham
- Department of Biology, Geology, and Physical Sciences, Sul Ross State University, USA
| | - Tracy Langkilde
- Department of Biology, The Pennsylvania State University, USA; Intercollege Graduate Degree Program in Ecology, and The Center for Brain, Behavior and Cognition, The Pennsylvania State University, USA
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Spence AR, Durso AM, Smith GD, Skinner HM, French SS. Physiological Correlates of Multiple Parasitic Infections in Side-Blotched Lizards. Physiol Biochem Zool 2017; 90:321-327. [PMID: 28384422 DOI: 10.1086/691059] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We investigated the presence of ectoparasites and hemoparasites in side-blotched lizards (Uta stansburiana) across a large part of their range and measured how parasitic infection related to several key physiological indicators of health. Blood samples were collected from 132 lizards from central Arizona, southern Utah, and eastern Oregon. Hemoparasites were found in 22 individuals (3.2% prevalence in Arizona, 19.1% in Utah, and 6.3% in Oregon), and ectoparasites were found on 51 individuals (56.3% prevalence in Arizona, 56.1% in Utah, and 6.7% in Oregon), with 11 individuals infected with both. Hemoparasites and ectoparasites were found in all three states. Immunocompetence was higher in individuals infected with both hemoparasites and ectoparasites. Body condition, glucocorticoid levels, and reproductive investment were not related to infection status. Our study provides evidence that parasitic infection is associated with an active immune system in wild reptiles but may not impose other costs usually associated with parasites.
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Neuman-Lee LA, French SS. Endocrine-reproductive-immune interactions in female and male Galápagos marine iguanas. Horm Behav 2017; 88:60-69. [PMID: 27818221 DOI: 10.1016/j.yhbeh.2016.10.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 10/25/2016] [Accepted: 10/28/2016] [Indexed: 12/14/2022]
Abstract
Endocrine-immune interactions are variable across species and contexts making it difficult to discern consistent patterns. There is a paucity of data in non-model systems making these relationships even more nebulous, particularly in reptiles. In the present study, we have completed a more comprehensive test of the relationship among steroid hormones and ecologically relevant immune measures. We tested the relationship between baseline and stress-induced levels of sex and adrenal steroid hormones and standard ecoimmunological metrics in both female and male Galápagos marine iguanas (Amblyrhynchus cristatus). We found significant associations between adrenal activity and immunity, whereby females that mounted greater corticosterone responses to stress had lower basal and stress-induced immunity (i.e., bactericidal ability). Males showed the opposite relationship, suggesting sex-specific immunomodulatory actions of corticosterone. In both sexes, we observed a stress-induced increase in corticosterone, and in females a stress-induced increase in bactericidal ability. Consistent with other taxa, we also found that baseline corticosterone and testosterone in males was inversely related to baseline bactericidal ability. However, in females, we found a positive relationship between both testosterone and progesterone and bactericidal ability. Multivariate analysis did not discern any further endocrine-immune relationships, suggesting that interactions between adrenal, sex steroid hormones, and the immune system may not be direct and instead may be responding to other common stimuli, (i.e., reproductive status, energy). Taken together, these data illustrate significant endocrine-immune interactions that are highly dependent on sex and the stress state of the animal.
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Affiliation(s)
- Lorin A Neuman-Lee
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, USA; The Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT 84322-5205, USA
| | - Susannah S French
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, USA; The Ecology Center, Utah State University, 5205 Old Main Hill, Logan, UT 84322-5205, USA.
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Spence AR, Hopkins GR, Neuman-Lee LA, Smith GDS, Brodie ED, French SS. Detrimental Effects of Zinc Oxide Nanoparticles on Amphibian Life Stages. ACTA ACUST UNITED AC 2016; 325:415-24. [DOI: 10.1002/jez.2026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/01/2016] [Accepted: 07/01/2016] [Indexed: 01/29/2023]
Affiliation(s)
| | - Gareth Rowland Hopkins
- Department of Biology; Utah State University; Logan Utah
- The Ecology Center; Utah State University; Logan Utah
- School of Biosciences; University of Melbourne; Parkville VIC Australia
| | | | - Geoffrey David Stuart Smith
- Department of Biology; Utah State University; Logan Utah
- The Ecology Center; Utah State University; Logan Utah
| | - Edmund Darrell Brodie
- Department of Biology; Utah State University; Logan Utah
- The Ecology Center; Utah State University; Logan Utah
| | - Susannah Smith French
- Department of Biology; Utah State University; Logan Utah
- The Ecology Center; Utah State University; Logan Utah
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Hopkins GR, Brodie ED, Neuman-Lee LA, Mohammadi S, Brusch GA, Hopkins ZM, French SS. Physiological Responses to Salinity Vary with Proximity to the Ocean in a Coastal Amphibian. Physiol Biochem Zool 2016; 89:322-30. [DOI: 10.1086/687292] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Harris BN, Carr JA. The role of the hypothalamus-pituitary-adrenal/interrenal axis in mediating predator-avoidance trade-offs. Gen Comp Endocrinol 2016; 230-231:110-42. [PMID: 27080550 DOI: 10.1016/j.ygcen.2016.04.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 04/07/2016] [Accepted: 04/09/2016] [Indexed: 11/20/2022]
Abstract
Maintaining energy balance and reproducing are important for fitness, yet animals have evolved mechanisms by which the hypothalamus-pituitary-adrenal/interrenal (HPA/HPI) axis can shut these activities off. While HPA/HPI axis inhibition of feeding and reproduction may have evolved as a predator defense, to date there has been no review across taxa of the causal evidence for such a relationship. Here we review the literature on this topic by addressing evidence for three predictions: that exposure to predators decreases reproduction and feeding, that exposure to predators activates the HPA/HPI axis, and that predator-induced activation of the HPA/HPI axis inhibits foraging and reproduction. Weight of evidence indicates that exposure to predator cues inhibits several aspects of foraging and reproduction. While the evidence from fish and mammals supports the hypothesis that predator cues activate the HPA/HPI axis, the existing data in other vertebrate taxa are equivocal. A causal role for the HPA axis in predator-induced suppression of feeding and reproduction has not been demonstrated to date, although many studies report correlative relationships between HPA activity and reproduction and/or feeding. Manipulation of HPA/HPI axis signaling will be required in future studies to demonstrate direct mediation of predator-induced inhibition of feeding and reproduction. Understanding the circuitry linking sensory pathways to their control of the HPA/HPI axis also is needed. Finally, the role that fear and anxiety pathways play in the response of the HPA axis to predator cues is needed to better understand the role that predators have played in shaping anxiety related behaviors in all species, including humans.
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Affiliation(s)
- Breanna N Harris
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, United States
| | - James A Carr
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, United States.
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Bennett AM, Longhi JN, Chin EH, Burness G, Kerr LR, Murray DL. Acute changes in whole body corticosterone in response to perceived predation risk: A mechanism for anti-predator behavior in anurans? Gen Comp Endocrinol 2016; 229:62-6. [PMID: 26944484 DOI: 10.1016/j.ygcen.2016.02.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/19/2016] [Accepted: 02/29/2016] [Indexed: 01/07/2023]
Abstract
Anuran larvae exhibit behavioral and morphological plasticity in response to perceived predation risk, although response type and magnitude varies through ontogeny. Increased baseline corticosterone is related to morphological response to predation risk, whereas the mechanism behind behavioral plasticity remains enigmatic. Since tadpoles alter behavioral responses to risk immediately upon exposure to predator cues, we characterized changes in whole body corticosterone at an acute (<1h post-exposure) timescale. Tadpoles (Lithobates sylvaticus) at Gosner stage (GS) 25 (free-swimming, feeding larvae) increased corticosterone levels to a peak at 10-20min post-exposure to predator cues, paralleling the acute stress response observed among other taxa. Tadpoles reared for 3weeks (mean GS29) with predation risk (caged, fed Aeshnid dragonfly nymph) had lower corticosterone levels at 10-20min post-exposure to dragonfly cues than predator-naïve controls, suggesting habituation, although the magnitude of increase was markedly diminished when compared to younger tadpoles (GS25). These experiments represent the first assessment of tadpole hormonal responses to predation risk at the acute timescale. Further research is required to establish causality between hormonal responses and behavioral changes, and to examine how and why responsiveness changes over ontogeny and with chronic exposure to risk.
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Affiliation(s)
- Amanda M Bennett
- Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada.
| | - Jessica N Longhi
- Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada
| | - Eunice H Chin
- Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada
| | - Gary Burness
- Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada; Biology Department, Trent University, Life & Health Science Building, 2140 East Bank Drive, Peterborough, Ontario K9J 7B8, Canada
| | - Leslie R Kerr
- Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada; Biology Department, Trent University, Life & Health Science Building, 2140 East Bank Drive, Peterborough, Ontario K9J 7B8, Canada
| | - Dennis L Murray
- Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada; Biology Department, Trent University, Life & Health Science Building, 2140 East Bank Drive, Peterborough, Ontario K9J 7B8, Canada
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