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Hernandez SE, Avila-Flores R, De Villa-Meza A, Romano MC. Evaluation of stress response in black-tailed prairie dogs (Cynomys ludovicianus) in arid regions from colonies in Chihuahua Mexico. Gen Comp Endocrinol 2023; 330:114150. [PMID: 36349607 DOI: 10.1016/j.ygcen.2022.114150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 10/18/2022] [Accepted: 10/25/2022] [Indexed: 11/04/2022]
Abstract
Among all the regulatory homeostatic networks in vertebrates, the activation of the hypothalamic-pituitaryadrenal axis during the stress response, has gained considerable attention, and the measurement of fecal glucocorticoids (FGC) has become an invaluable tool to assess adrenocortical activity related to stressful events in wild and captive animals. However, the use of FGC requires the validation of measurement techniques and the proper selection of the specific hormone according to the study species. The main objective of this study was to identify the dominant glucocorticoid (GC) hormone in the stress response of black-tailed prairie dogs (Cynomys ludovicianus) in an arid grassland of Chihuahua, Mexico. A capture stress challenge in the field was developed to determine if the levels of glucocorticoids (cortisol and corticosterone) both in serum and fecal samples could be attributed to stress in Cynomys ludovicianus. The samples were analysed with the technique of liquid phase radioimmunoassay , and this study showed that both cortisol and corticosterone are present at measurable levels in serum and fecal samples of black-tailed prairie dogs. We found that both GCs were present in similar concentrations in serum, however, corticosterone concentration in fecal samples was higher than cortisol. Likewise, biochemical validations performed in this study to test the assay reached acceptable levels of reliability. Therefore, we confirm that fecal analysis can be implemented as a method to measure stress responses in wild prairie dogs.
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Affiliation(s)
- S E Hernandez
- Cuerpo Académico en Ciencia Animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de Tamaulipas, Ciudad Victoria, Tamaulipas, CP 87274, Mexico.
| | - R Avila-Flores
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, CP 86150, Mexico
| | - A De Villa-Meza
- Independent consultant, Benito Juárez, Ciudad de México, CP 03610, Mexico
| | - M C Romano
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV-IPN, Ciudad de México, CP 07360, Mexico
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Effects of social stress on the welfare of captive male Alpine musk deer: Stereotypic behavior, fecal cortisol, and musk secretion. Appl Anim Behav Sci 2023. [DOI: 10.1016/j.applanim.2022.105828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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3
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O'Brien SL, Irian CG, Bentley GE, Lacey EA. Sex, not social behavior, predicts fecal glucocorticoid metabolite concentrations in a facultatively social rodent, the highland tuco-tuco (Ctenomys opimus). Horm Behav 2022; 141:105152. [PMID: 35286897 DOI: 10.1016/j.yhbeh.2022.105152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 11/24/2022]
Abstract
Social relationships may influence circulating glucocorticoid levels, particularly in group-living species in which individuals regularly engage in interactions with conspecifics. The effects of such interactions appear to vary, with greater social contact being associated with increased glucocorticoid concentrations in some species but decreased concentrations in others. These distinct responses raise intriguing questions regarding relationships among social behavior, individual phenotypes, and glucocorticoid physiology. To explore such relationships in a free-living mammal with a dynamic social organization, we quantified variation in baseline glucocorticoids in a population of highland tuco-tucos (Ctenomys opimus) from Jujuy Province, Argentina. These subterranean rodents are facultatively social, with lone and group-living individuals regularly occurring within the same population. To assess potential endocrine correlates of this behavioral variability, we examined differences in baseline fecal glucocorticoid metabolite (fGCm) concentrations as a function of social group size and composition as well as several metrics of social behavior derived from social network analyses. Despite marked variability in social relationships among the 37 (12 male, 25 female) free-living tuco-tucos sampled, none of the measures of social behavior examined were significant predictors of variation in fGCm concentrations. In contrast, individual variation in glucocorticoid metabolites was best explained by sex, with males having higher fGCm concentrations than females. These analyses provide the first characterization of the glucocorticoid physiology of highland tuco-tucos and underscore the potential importance of intrinsic phenotypic factors (e.g., sex) in shaping glucocorticoid variation in free-living mammals.
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Affiliation(s)
- Shannon L O'Brien
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA; Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
| | - Christian G Irian
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
| | - George E Bentley
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Eileen A Lacey
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA; Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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Ebensperger LA, Quirici V, Bunster V, León C, Ramírez‐Estrada J, Hayes LD. Effects of Radio‐Collars are not Contingent on Socioecological Conditions in Degus. J Wildl Manage 2021. [DOI: 10.1002/jwmg.22098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Luis A. Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Verónica Quirici
- Centro de Investigación para la Sustentabilidad Facultad de Ciencias de la Vida, Universidad Andrés Bello, República 440 Santiago Chile
| | - Valentina Bunster
- Departamento de Ecología, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Cecilia León
- Departamento de Ecología, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Juan Ramírez‐Estrada
- Departamento de Ecología, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Loren D. Hayes
- Department of Biology, Geology, and Environmental Sciences University of Tennessee at Chattanooga Chattanooga 37403 TN USA
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Zemanova MA. Towards more compassionate wildlife research through the 3Rs principles: moving from invasive to non-invasive methods. WILDLIFE BIOLOGY 2020. [DOI: 10.2981/wlb.00607] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Miriam A. Zemanova
- M. A. Zemanova (https://orcid.org/0000-0002-5002-3388) ✉ , Dept of Philosophy, Univ. of Basel, Steinengraben 5, CH-4051 Basel, Switzerland
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Scheun J, Geiser F, Ganswindt A, Nowack J. Non-invasive evaluation of stress hormone responses in a captive population of sugar gliders (Petaurus breviceps). AUSTRALIAN MAMMALOGY 2020. [DOI: 10.1071/am18044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Faecal hormone monitoring offers a robust tool to non-invasively determine the physiological stress experienced by an individual when faced with natural or human-driven stressors. Although already quantified for several species, the method needs to be validated for each new species to ensure reliable quantification of the respective glucocorticoids. Here we investigated whether measurement of faecal glucocorticoid metabolite (fGCM) provides a feasible and non-invasive way to assess the physiological state of sugar gliders (Petaurus breviceps), an arboreal marsupial native to Australia, by using both a biological and physiological validation. Our analysis confirmed that the cortisol enzyme immunoassay (EIA) was the most appropriate assay for monitoring fGCM concentrations in sugar gliders. Comparing the fGCM response to the physiological and the biological validation, we found that while the administration of ACTH led to a significant increase in fGCM concentration in all individuals, only six of eight individuals showed a considerable fGCM response following the biological validation. Our study identified the most appropriate immunoassay for monitoring fGCM concentrations as an indicator of physiological stress in sugar gliders, but also supports recent suggestions that, if possible, both biological and physiological stressors should be used when testing the suitability of an EIA for a species.
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Hammond TT, Vo M, Burton CT, Surber LL, Lacey EA, Smith JE. Physiological and behavioral responses to anthropogenic stressors in a human-tolerant mammal. J Mammal 2019. [DOI: 10.1093/jmammal/gyz134] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Abstract
As humans continue to alter natural habitats, many wild animals are facing novel suites of environmental stimuli. These changes, including increased human–wildlife interactions, may exert sublethal impacts on wildlife such as alterations in stress physiology and behavior. California ground squirrels (Otospermophilus beecheyi) occur in human-modified as well as more pristine environments, where they face a variety of anthropogenic and naturally occurring threats. This makes this species a valuable model for examining the effects of diverse challenges on the physiology and behavior of free-living mammals. To explore potential sublethal effects of habitat modification on O. beecheyi, we compared body masses, behaviors, and fecal glucocorticoid metabolite (FGM) levels for free-living squirrels in human-disturbed versus undisturbed habitats. Prior to these analyses, we validated the use of FGMs in this species by exposing captive O. beecheyi to pharmacological and handling challenges; both challenges produced significant increases in FGMs in the study animals. While FGM responses were repeatable within captive individuals, responses by free-living animals were more variable, perhaps reflecting a greater range of life-history traits and environmental conditions within natural populations of squirrels. Animals from our human-disturbed study site had significantly higher FGMs, significantly lower body masses, and were significantly less behaviorally reactive to humans than those from our more pristine study site. Thus, despite frequent exposure of California ground squirrels to human impacts, anthropogenic stressors appear to influence stress physiology and other phenotypic traits in this species. These findings suggest that even human-tolerant mammalian species may experience important sublethal consequences due to human modifications of natural habitats.
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Affiliation(s)
- Talisin T Hammond
- San Diego Zoo Institute for Conservation Research, Escondido, CA, USA
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
| | - Minnie Vo
- Biology Department, Mills College, Oakland, CA, USA
| | | | | | - Eileen A Lacey
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
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Ovejero Aguilar RJ, Jahn GA, Soto-Gamboa M, Novaro AJ, Carmanchahi P. The Ecology of Stress: linking life-history traits with physiological control mechanisms in free-living guanacos. PeerJ 2016; 4:e2640. [PMID: 27833807 PMCID: PMC5101617 DOI: 10.7717/peerj.2640] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 09/30/2016] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Providing the context for the evolution of life-history traits, habitat features constrain successful ecological and physiological strategies. In vertebrates, a key response to life's challenges is the activation of the Stress (HPA) and Gonadal (HPG) axes. Much of the interest in stress ecology is motivated by the desire to understand the physiological mechanisms in which the environment affects fitness. As reported in the literature, several intrinsic and extrinsic factors affect variability in hormone levels. In both social and non-social animals, the frequency and type of interaction with conspecifics, as well as the status in social species, can affect HPA axis activity, resulting in changes in the reproductive success of animals. We predicted that a social environment can affect both guanaco axes by increasing the secretion of testosterone (T) and Glucocorticoid (GCs) in response to individual social interactions and the energetic demands of breeding. Assuming that prolonged elevated levels of GCs over time can be harmful to individuals, it is predicted that the HPA axis suppresses the HPG axis and causes T levels to decrease, as GCs increase. METHODS All of the data for individuals were collected by non-invasive methods (fecal samples) to address hormonal activities. This is a novel approach in physiological ecology because feces are easily obtained through non-invasive sampling in animal populations. RESULTS As expected, there was a marked adrenal (p-value = .3.4e-12) and gonadal (p-value = 0.002656) response due to seasonal variation in Lama guanicoe. No significant differences were found in fecal GCs metabolites between males/females*season for the entire study period (p-value = 0.2839). Despite the seasonal activity variation in the hormonal profiles, our results show a positive correlation (p-value = 1.952e-11, COR = 0.50) between the adrenal and gonadal system. The marked endocrine (r2 = 0.806) and gonad (r2 = 0.7231) response due to seasonal variation in male guanaco individuals highlights the individual's energetic demands according to life-history strategies. This is a remarkable result because no inhibition was found between the axes as theory suggests. Finally, the dataset was used to build a reactive scope model for guanacos. DISCUSSION Guanacos cope with the trade-off between sociability and reproductive benefits and costs, by regulating their GCs and T levels on a seasonal basis, suggesting an adaptive role of both axes to different habitat pressures. The results presented here highlight the functional role of stress and gonad axes on a critical phase of a male mammal's life-the mating period-when all of the resources are at the disposal of the male and must be used to maximize the chances for reproductive success.
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Affiliation(s)
- Ramiro J.A. Ovejero Aguilar
- Laboratorio de Ecología Conductual, Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
- Laboratorio de Interacciones Ecológicas, Instituto de investigaciones den zonas áridas (CONICET-MENDOZA-LIE-IADIZA), Mendoza, Argentina
- Grupo de Investigación de Eco-fisiología de Fauna Silvestre (GIEFAS), Asentamiento Universitario de San Martín de los Andes (AUSMA), Universidad Nacional del Comahue (INIBIOMA-CONICET-AUSMA-UNCo), Neuquén, Argentina
| | - Graciela A. Jahn
- Laboratorio de Reproducción y Lactancia, Universidad de Mendoza (IMBECU-CCT-MENDOZA), Mendoza, Argentina
| | - Mauricio Soto-Gamboa
- Laboratorio de Ecología Conductual, Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Andrés J. Novaro
- Programa Estepa-Andino Patagonica-CONICET-PATAGONIA NORTE-INIBIOMA, Neuquén, Argentina
| | - Pablo Carmanchahi
- Grupo de Investigación de Eco-fisiología de Fauna Silvestre (GIEFAS), Asentamiento Universitario de San Martín de los Andes (AUSMA), Universidad Nacional del Comahue (INIBIOMA-CONICET-AUSMA-UNCo), Neuquén, Argentina
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Ebensperger LA, León C, Ramírez-Estrada J, Abades S, Hayes LD, Nova E, Salazar F, Bhattacharjee J, Becker MI. Immunocompetence of breeding females is sensitive to cortisol levels but not to communal rearing in the degu (Octodon degus). Physiol Behav 2014; 140:61-70. [PMID: 25497887 DOI: 10.1016/j.physbeh.2014.12.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 01/15/2023]
Abstract
One hypothesis largely examined in social insects is that cooperation in the context of breeding benefits individuals through decreasing the burden of immunocompetence and provide passive immunity through social contact. Similarly, communal rearing in social mammals may benefit adult female members of social groups by reducing the cost of immunocompetence, and through the transfer of immunological compounds during allonursing. Yet, these benefits may come at a cost to breeders in terms of a need to increase investment in individual immunocompetence. We examined how these potential immunocompetence costs and benefits relate to reproductive success and survival in a natural population of the communally rearing rodent, Octodon degus. We related immunocompetence (based on ratios of white blood cell counts, total and specific immunoglobulins of G isotype titers) and fecal glucocorticoid metabolite (FGC) levels of adults immunized with hemocyanin from the mollusk Concholepas concholepas to measures of sociality (group size) and communal rearing (number of breeding females). Offspring immunocompetence was quantified based on circulating levels of the same immune parameters. Neither female nor offspring immunocompetence was influenced by communal rearing or sociality. These findings did not support that communal rearing and sociality enhance the ability of females to respond to immunological challenges during lactation, or contribute to enhance offspring condition (based on immunocompetence) or early survival (i.e., to 3months of age). Instead, levels of humoral and cellular components of immunocompetence were associated with variation in glucorcorticoid levels of females. We hypothesize that this covariation is driven by physiological (life-history) adjustments needed to sustain breeding.
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Affiliation(s)
- Luis A Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
| | - Cecilia León
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Juan Ramírez-Estrada
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Sebastian Abades
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile; Instituto de Ecología y Biodiversidad (IEB), Las Palmeras 3425, Ñuñoa, Santiago, Chile
| | - Loren D Hayes
- Department of Biological and Environmental Sciences, University of Tennessee at Chattanooga, Chattanooga, TN 37403, USA
| | - Esteban Nova
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago, Chile
| | - Fabián Salazar
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago, Chile
| | | | - María Inés Becker
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago, Chile; Biosonda Corporation, Santiago, Chile
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Woodruff JA, Lacey EA, Bentley GE, Kriegsfeld LJ. Effects of social environment on baseline glucocorticoid levels in a communally breeding rodent, the colonial tuco-tuco (Ctenomys sociabilis). Horm Behav 2013; 64:566-72. [PMID: 23928366 DOI: 10.1016/j.yhbeh.2013.07.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 07/28/2013] [Accepted: 07/29/2013] [Indexed: 11/30/2022]
Abstract
The social environment in which an animal lives can profoundly impact its physiology, including glucocorticoid (GC) responses to external stressors. In social, group-living species, individuals may face stressors arising from regular interactions with conspecifics as well as those associated with basic life history needs such as acquiring food or shelter. To explore the relative contributions of these two types of stressors on glucocorticoid physiology in a communally breeding mammal, we characterized baseline GC levels in female colonial tuco-tucos (Ctenomys sociabilis), which are subterranean rodents endemic to southwestern Argentina. Long-term field studies have revealed that while about half of all yearling female C. sociabilis live and breed alone, the remainder live and breed within their natal group. We assessed the effects of this intraspecific variation in social environment on GC physiology by comparing concentrations of baseline fecal corticosterone metabolite (fCM) for (1) lone and group-living yearling females in a free-living population of C. sociabilis and (2) captive yearling female C. sociabilis that had been experimentally assigned to live alone or with conspecifics. In both cases, lone females displayed significantly higher mean baseline fCM concentrations. Data from free-living animals indicated that this outcome arose from differences in circadian patterns of GC production. fCM concentrations for group-living animals declined in the afternoon while fCM in lone individuals did not. These findings suggest that for C. sociabilis, stressors associated with basic life history functions present greater challenges than those arising from interactions with conspecifics. Our study is one of the first to examine GC levels in a plural-breeding mammal in which the effects of group-living are not confounded by differences in reproductive or dominance status, thereby generating important insights into the endocrine consequences of group-living.
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Affiliation(s)
- Julie A Woodruff
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA; Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
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Ebensperger LA, Tapia D, Ramírez-Estrada J, León C, Soto-Gamboa M, Hayes LD. Fecal cortisol levels predict breeding but not survival of females in the short-lived rodent, Octodon degus. Gen Comp Endocrinol 2013; 186:164-71. [PMID: 23524002 DOI: 10.1016/j.ygcen.2013.02.044] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 02/20/2013] [Accepted: 02/23/2013] [Indexed: 12/01/2022]
Abstract
The cort-adaptation hypothesis indicates that an association between glucocorticoid (cort) levels and fitness may vary with the extent to which reproduction or breeding effort is a major determinant of cort levels. Support for a context dependent association between cort and fitness comes mostly from relatively long-lived, bird species. We tested the hypothesis that there are gender and context (life-history) specific cort-fitness relationships in degus, a short-lived and generally semelparous social rodent. In particular, we used demographical records on a natural population to estimate adult survival through seasons and years and linked that to records of baseline cort (based on fecal cortisol metabolites). We found no evidence for a direct relationship between baseline cort and adult survival across seasons, and this lack of association was recorded irrespective of sex and life history stage. Yet, cort levels during early lactation predicted the probability that females produce a second litter during the same breeding season, supporting a connection between baseline cort levels and breeding effort. Overall, the differential effects of cort on survival and breeding supported that the extent of cort-fitness relationships depends on the fitness component examined.
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Affiliation(s)
- Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología and Biodiversidad (CASEB), and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
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Smith JE, Monclús R, Wantuck D, Florant GL, Blumstein DT. Fecal glucocorticoid metabolites in wild yellow-bellied marmots: experimental validation, individual differences and ecological correlates. Gen Comp Endocrinol 2012; 178:417-26. [PMID: 22732084 DOI: 10.1016/j.ygcen.2012.06.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Revised: 05/09/2012] [Accepted: 06/08/2012] [Indexed: 11/15/2022]
Abstract
Natural selection is expected to shape phenotypic traits that permit organisms to respond appropriately to the environments in which they live. One important mechanism by which animals cope with changes in their environment is through physiological responses to stressors mediated by glucocorticoid hormones. Here we perform biological and physiological validations of a minimally-invasive technique for assessing fecal corticosterone metabolites (FCMs) in captive and wild groups of yellow-bellied marmots (Marmota flaviventris). Then we draw from ten years of data on these obligate hibernators at the Rocky Mountain Biological Laboratory in Colorado, USA to assess the extent to which seasonal and daily changes explain naturalistic variation in baseline levels of FCMs. Interestingly, beyond important population-level variation with respect to year, season, time of day, sex, age and reproductive state, we found repeatable inter-individual differences in FCMs, suggesting this hormonal trait might be a meaningful target of selection. FCM levels were 68% lower in captive than wild marmots, suggesting that the natural environment in which these animals occur is generally more challenging or less predictable than life in captivity. Most live-trapping events failed to represent stressors for wild marmots such that repeated measurements of traits were possible with minimal "stress" to subjects. We also document the natural ranges of annual and seasonal variation necessary for understanding the extent to which anthropogenic assaults represent stressors for wild mammals. Taken together, this study provides a foundation for understanding the evolution of hormonal traits and has important welfare and conservation implications for field biologists.
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Affiliation(s)
- Jennifer E Smith
- Department of Ecology & Evolutionary Biology, University of California, 621 Charles E. Young Drive South, Los Angeles, CA 90095-1606, USA.
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VERA FEDERICO, ZENUTO ROXANARITA, ANTENUCCI CARLOSDANIEL. Differential Responses of Cortisol and Corticosterone to Adrenocorticotropic Hormone (ACTH) in a Subterranean Rodent (Ctenomys talarum). ACTA ACUST UNITED AC 2012; 317:173-84. [DOI: 10.1002/jez.1711] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Vera F, Zenuto RR, Antenucci CD, Busso JM, Marín RH. Validation of a radioimmunoassay for measuring testosterone concentrations in plasma samples of the subterranean rodent Ctenomys talarum: outstandingly elevated levels in the wild and the effect of captivity. ACTA ACUST UNITED AC 2011; 315:572-83. [DOI: 10.1002/jez.707] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 08/01/2011] [Accepted: 08/03/2011] [Indexed: 12/22/2022]
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Ebensperger LA, Ramírez-Estrada J, León C, Castro RA, Tolhuysen LO, Sobrero R, Quirici V, Burger JR, Soto-Gamboa M, Hayes LD. Sociality, glucocorticoids and direct fitness in the communally rearing rodent, Octodon degus. Horm Behav 2011; 60:346-52. [PMID: 21777588 DOI: 10.1016/j.yhbeh.2011.07.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/21/2011] [Accepted: 07/01/2011] [Indexed: 11/16/2022]
Abstract
While ecological causes of sociality (or group living) have been identified, proximate mechanisms remain less clear. Recently, close connections between sociality, glucocorticoid hormones (cort) and fitness have been hypothesized. In particular, cort levels would reflect a balance between fitness benefits and costs of group living, and therefore baseline cort levels would vary with sociality in a way opposite to the covariation between sociality and fitness. However, since reproductive effort may become a major determinant of stress responses (i.e., the cort-adaptation hypothesis), cort levels might also be expected to vary with sociality in a way similar to the covariation between sociality and fitness. We tested these expectations during three years in a natural population of the communally rearing degu, Octodon degus. During each year we quantified group membership, measured fecal cortisol metabolites (a proxy of baseline cort levels under natural conditions), and estimated direct fitness. We recorded that direct fitness decreases with group size in these animals. Secondly, neither group size nor the number of females (two proxies of sociality) influenced mean (or coefficient of variation, CV) baseline cortisol levels of adult females. In contrast, cortisol increased with per capita number of offspring produced and offspring surviving to breeding age during two out of three years examined. Together, our results imply that variation in glucocorticoid hormones is more linked to reproductive challenge than to the costs of group living. Most generally, our study provided independent support to the cort-adaptation hypothesis, according to which reproductive effort is a major determinant, yet temporally variable, influence on cort-fitness covariation.
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Affiliation(s)
- Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología and Biodiversidad (CASEB), and Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
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Hayes LD, Burger JR, Soto-Gamboa M, Sobrero R, Ebensperger LA. Towards an integrative model of sociality in caviomorph rodents. J Mammal 2011; 92:65-77. [PMID: 22328791 PMCID: PMC3277430 DOI: 10.1644/10-mamm-s-039.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In the late 1990s and early 2000s it was recognized that behavioral ecologists needed to study the sociality of caviomorph rodents (New World hystricognaths) before generalizations about rodent sociality could be made. Researchers identified specific problems facing individuals interested in caviomorph sociality, including a lack of information on the proximate mechanisms of sociality, role of social environment in development, and geographical or intraspecific variation in social systems. Since then researchers have described the social systems of many previously understudied species, including some with broad geographical ranges. Researchers have done a good job of determining the role of social environments in development and identifying the costs and benefits of social living. However, relatively little is known about the proximate mechanisms of social behavior and fitness consequences, limiting progress toward the development of integrative (evolutionary-mechanistic) models for sociality. To develop integrative models behavioral ecologists studying caviomorph rodents must generate information on the fitness consequences of different types of social organization, brain mechanisms, and endocrine substrates of sociality. We review our current understanding and future directions for research in these conceptual areas. A greater understanding of disease ecology, particularly in species carrying Old World parasites, is needed before we can identify potential links between social phenotypes, mechanism, and fitness.
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Affiliation(s)
- Loren D. Hayes
- Department of Biology, 700 University Avenue, University of Louisiana at Monroe, Monroe, LA 72109, USA
| | - Joseph Robert Burger
- Department of Biology, 700 University Avenue, University of Louisiana at Monroe, Monroe, LA 72109, USA
- Department of Biology, MSC03 2020/1, University of New Mexico, Albuquerque, NM 87131, USA
| | - Mauricio Soto-Gamboa
- Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile, Isla teja S/N, Casilla 567, Chile
| | - Raúl Sobrero
- Centro de Estudios Avanzados en Ecología y Biodiversidad and Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O’Higgins 340, Santiago, Chile
| | - Luis A Ebensperger
- Centro de Estudios Avanzados en Ecología y Biodiversidad and Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O’Higgins 340, Santiago, Chile
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Quirici V, Faugeron S, Hayes LD, Ebensperger LA. The influence of group size on natal dispersal in the communally rearing and semifossorial rodent, Octodon degus. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1082-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Woodruff JA, Lacey EA, Bentley G. Contrasting fecal corticosterone metabolite levels in captive and free-living colonial tuco-tucos (Ctenomys sociabilis). ACTA ACUST UNITED AC 2010; 313:498-507. [DOI: 10.1002/jez.621] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sex differences in the excretion of fecal glucocorticoid metabolites in the Syrian hamster. J Comp Physiol B 2010; 180:919-25. [DOI: 10.1007/s00360-010-0467-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 03/07/2010] [Accepted: 03/08/2010] [Indexed: 10/19/2022]
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