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Veloso-Frías J, Soto-Gamboa M, Mastromonaco G, Acosta-Jamett G. Seasonal Hair Glucocorticoid Fluctuations in Wild Mice ( Phyllotis darwini) within a Semi-Arid Landscape in North-Central Chile. Animals (Basel) 2024; 14:1260. [PMID: 38731264 PMCID: PMC11083726 DOI: 10.3390/ani14091260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/15/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024] Open
Abstract
Mammals in drylands face environmental challenges exacerbated by climate change. Currently, human activity significantly impacts these environments, and its effects on the energy demands experienced by individuals have not yet been determined. Energy demand in organisms is managed through elevations in glucocorticoid levels, which also vary with developmental and health states. Here, we assessed how anthropization, individual characteristics, and seasonality influence hair glucocorticoid concentration in the Darwin's leaf-eared mouse (Phyllotis darwini) inhabiting two areas with contrasting anthropogenic intervention in a semi-arid ecosystem of northern Chile. Hair samples were collected (n = 199) to quantify hair corticosterone concentration (HCC) using enzyme immunoassays; additionally, sex, body condition, and ectoparasite load were recorded. There were no differences in HCC between anthropized areas and areas protected from human disturbance; however, higher concentrations were recorded in females, and seasonal fluctuations were experienced by males. The results indicate that animals inhabiting semi-arid ecosystems are differentially stressed depending on their sex. Additionally, sex and season have a greater impact on corticosterone concentration than anthropogenic perturbation, possibly including temporal factors, precipitation, and primary production. The influence of sex and seasonality on HCC in P. darwini make it necessary to include these variables in future stress assessments of this species.
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Affiliation(s)
- Joseline Veloso-Frías
- Institute of Preventive Veterinary Medicine, Austral University of Chile, Valdivia 5090000, Chile;
| | - Mauricio Soto-Gamboa
- Institute of Environmental and Evolutionary Sciences, Austral University of Chile, Valdivia 5090000, Chile;
| | | | - Gerardo Acosta-Jamett
- Institute of Preventive Veterinary Medicine, Austral University of Chile, Valdivia 5090000, Chile;
- Center for Surveillance and Evolution of Infectious Diseases (CSEID), Austral University of Chile, Valdivia 5090000, Chile
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2
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Rogers FD, Peña CJ, Mallarino R. African striped mice (Rhabdomys pumilio) as a neurobehavioral model for male parental care. Horm Behav 2023; 152:105364. [PMID: 37087766 DOI: 10.1016/j.yhbeh.2023.105364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/27/2023] [Accepted: 04/12/2023] [Indexed: 04/25/2023]
Abstract
Parental care is diversely demonstrated across the animal kingdom, such that active practitioners and repertoires of parental behavior vary dramatically between and within taxa. For mammals, maternal care is ubiquitous while paternal and alloparental care are rare. The African striped mouse, a rodent species in the family Muridae, demonstrates maternal, paternal, and alloparental care. Because socio-environmental factors can considerably influence the development of their social behavior, including that of paternal and alloparental care, African striped mice are considered socially flexible. Here, we highlight African striped mice as a new model for the neurobiological study of male parental care. We first provide essential background information on the species' natural ecological setting and reproductive behavior, as well as the species-relevant interaction between ecology and reproduction. We then introduce the nature of maternal, paternal, and alloparental care in the species. Lastly, we provide a review of existing developmental and neurobiological perspectives and highlight potential avenues for future research.
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Affiliation(s)
- Forrest Dylan Rogers
- Princeton Neuroscience Institute, Princeton University, Washington Rd., Princeton, NJ 08544, United States of America; Department of Molecular Biology, Princeton University, 119 Lewis Thomas Laboratory, Washington Rd., Princeton, NJ 08544, United States of America.
| | - Catherine Jensen Peña
- Princeton Neuroscience Institute, Princeton University, Washington Rd., Princeton, NJ 08544, United States of America
| | - Ricardo Mallarino
- Department of Molecular Biology, Princeton University, 119 Lewis Thomas Laboratory, Washington Rd., Princeton, NJ 08544, United States of America
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3
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Schradin C, Makuya L, Pillay N, Rimbach R. Harshness is not stress. Trends Ecol Evol 2023; 38:224-227. [PMID: 36641304 DOI: 10.1016/j.tree.2022.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/24/2022] [Accepted: 12/08/2022] [Indexed: 01/15/2023]
Abstract
We must differentiate between stressful and harsh environments to understand animals' resilience to global change. Harshness is not stress. Stressful environments activate the physiological stress response to increase energy availability, while harsh environments inhibit the physiological stress response to save energy.
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Affiliation(s)
- Carsten Schradin
- CNRS, UMR7178, 67087 Strasbourg, France; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Lindelani Makuya
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Neville Pillay
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Rebecca Rimbach
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa; Department of Behavioural Biology, University of Münster, Münster, Germany
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4
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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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5
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Fitness consequences of chronic exposure to different light pollution wavelengths in nocturnal and diurnal rodents. Sci Rep 2022; 12:16486. [PMID: 36182961 PMCID: PMC9526750 DOI: 10.1038/s41598-022-19805-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 09/05/2022] [Indexed: 12/05/2022] Open
Abstract
Use of artificial at night (ALAN) exposes the world to continuously increasing levels and distribution of light pollution. Our understanding of the adverse effects of ALAN is based mostly on observational or laboratory studies, and its effects are probably underestimated. Demonstration of direct experimental fitness consequences of ALAN on mammals is missing. We studied the effects of chronic light pollution at different wavelengths on fitness and glucocorticoid hormone levels under semi-natural conditions in two closely related species: the nocturnal common spiny mouse (Acomys cahirinus) and the diurnal golden spiny mouse (Acomys russatus). Our results clearly demonstrate the adverse effects of ALAN exposure on the fitness of both nocturnal and diurnal species, manifested by changes in cortisol levels and reproductive timing, reduced reproductive output and reduced survival, which differed between species and wavelengths. In A. russatus exposure to blue ALAN had the strongest effect on fitness, followed by white and yellow ALAN exposure. In A. cahirinus the results are more complex and suggest it suffered from the combined effects of ALAN and competition. Our research shows that light pollution presents a real threat to both nocturnal and diurnal species, affecting the species fitness directly and through interspecific interactions. Worryingly, these effects are probably not limited to spiny mice. The clear adverse effects we documented, as well as the differences between wave lengths, contribute to our ability to present science-based recommendations to decision makers regarding the use of artificial light at night. Such information and guidelines are highly important nowadays when lighting systems are being replaced to promote energy efficiency.
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6
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Xu DL, Hu XK. Effect of Natural Seasonal Changes in Photoperiod and Temperature on Immune Function in Striped Hamsters. Zoolog Sci 2022; 39. [DOI: 10.2108/zs220005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 04/04/2022] [Indexed: 11/17/2022]
Affiliation(s)
- De-Li Xu
- College of Life Sciences, Qufu Normal University, Qufu, 273165, Shandong Province, China
| | - Xiao-Kai Hu
- College of Life Sciences, Qufu Normal University, Qufu, 273165, Shandong Province, China
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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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8
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Rimbach R, Hartman KJ, Currin C, Schradin C, Pillay N. Females of solitary- and group-living sister species of African striped mice show a similar social structure following experimentally imposed group-living. Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03144-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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9
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Hex SBSW, Tombak K, Rubenstein DI. A new classification of mammalian uni-male multi-female groups based on the fundamental principles governing inter- and intrasexual relationships. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03046-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Seasonal changes in problem-solving in wild African striped mice. Anim Cogn 2021; 25:401-413. [PMID: 34591197 DOI: 10.1007/s10071-021-01559-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 08/20/2021] [Accepted: 09/04/2021] [Indexed: 10/20/2022]
Abstract
Innovative problem-solving ability is a predictor of whether animals can successfully cope with environmental changes. These environmental changes can test the limits of animals, for example when energy availability decreases seasonally and, hence, problem-solving performance decreases because less energy is available for cognitive processes. Here, we investigated: (1) how problem-solving performance changed between seasons that differed significantly in food availability; (2) whether these changes were related to environmentally induced physiological changes in blood glucose and ketone levels, indicators of energy availability; and (3) whether individual variation in problem-solving was related to sex differences. We studied 99 free-ranging African striped mice, Rhabdomys pumilio, in the Succulent Karoo, South Africa, 55 during the hot dry summer with low food availability and 44 during the cold wet winter with higher food availability. We measured their problem-solving abilities using a food extraction task and found no seasonal differences in problem-solving success. However, mice solved the problem faster in summer versus winter. In summer, food availability was reduced and blood ketones increased but there was no seasonal difference in blood glucose levels. There were no correlation between problem-solving performance and blood glucose or ketone levels. Overall, more males solved the task than females. It appears that in striped mice cognitive functions can be maintained under harsh environmental conditions.
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11
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12
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Hill DL, Pillay N, Schradin C. Glucocorticoid levels predict subsequent social tactic in females of a facultatively social mammal. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Davina L. Hill
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
- Institute of Biodiversity, Animal Health and Comparative Medicine College of Medical, Veterinary and Life Sciences University of Glasgow Glasgow UK
| | - Neville Pillay
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
| | - Carsten Schradin
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
- Université de StrasbourgCNRSIPHC UMR 7178 Strasbourg France
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Reproductive events and respective faecal androgen metabolite concentrations in captive male roan antelope (Hippotragus equinus). PLoS One 2020; 15:e0243277. [PMID: 33332371 PMCID: PMC7745970 DOI: 10.1371/journal.pone.0243277] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 11/19/2020] [Indexed: 11/29/2022] Open
Abstract
Understanding the reproductive biology of the roan antelope (Hippotragus equinus) (É. Geoffroy Saint-Hilaire, 1803) is crucial to optimise breeding success in captive breeding programmes of this threatened species. In this study, the pattern of faecal androgen metabolite (fAM) production related to reproductive events (calving or birthing, mating, gestation, and lactation), sexual behaviours as well as environmental cues were studied in captive adult male roan antelope. Faecal sample collection and behavioural observations were carried out from August 2017 to July 2018 for three reproductive males participating in a conservation breeding programme at the Lapalala Wilderness Nature Reserve in South Africa. As a prerequisite, the enzyme immunoassay used in this study was biologically validated for the species by demonstrating a significant difference between fAM concentrations in non-breeding adults, breeding adults and juvenile males. Results revealed that in adults males, the overall mean fAM levels were 73% higher during the breeding period compared to the non-breeding periods, and 85% higher when exclusively compared to the lactation/gestation periods, but only 5.3% higher when compared to the birthing period. Simultaneously, fAM concentrations were lower during the wet season compared to the dry season, increasing with a reduction in photoperiod. With the exception of courtship, frequencies of sexual behaviours monitored changed in accordance with individual mean fAM concentrations in male roan antelope, the findings suggest that androgen production varies with the occurrence of mating activity and may be influenced by photoperiod but not with rainfall.
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14
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Criscuolo F, Pillay N, Zahn S, Schradin C. Seasonal variation in telomere dynamics in African striped mice. Oecologia 2020; 194:609-620. [DOI: 10.1007/s00442-020-04801-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 11/05/2020] [Indexed: 02/08/2023]
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15
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Jorgensen C, Wang Z. Hormonal Regulation of Mammalian Adult Neurogenesis: A Multifaceted Mechanism. Biomolecules 2020; 10:biom10081151. [PMID: 32781670 PMCID: PMC7465680 DOI: 10.3390/biom10081151] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 07/27/2020] [Accepted: 08/01/2020] [Indexed: 02/07/2023] Open
Abstract
Adult neurogenesis—resulting in adult-generated functioning, integrated neurons—is still one of the most captivating research areas of neuroplasticity. The addition of new neurons in adulthood follows a seemingly consistent multi-step process. These neurogenic stages include proliferation, differentiation, migration, maturation/survival, and integration of new neurons into the existing neuronal network. Most studies assessing the impact of exogenous (e.g., restraint stress) or endogenous (e.g., neurotrophins) factors on adult neurogenesis have focused on proliferation, survival, and neuronal differentiation. This review will discuss the multifaceted impact of hormones on these various stages of adult neurogenesis. Specifically, we will review the evidence for hormonal facilitation (via gonadal hormones), inhibition (via glucocorticoids), and neuroprotection (via recruitment of other neurochemicals such as neurotrophin and neuromodulators) on newly adult-generated neurons in the mammalian brain.
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Affiliation(s)
- Claudia Jorgensen
- Behavioral Science Department, Utah Valley University, Orem, UT 84058, USA
- Correspondence:
| | - Zuoxin Wang
- Psychology Department and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA;
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Stewart ND, Mastromonaco GF, Burness G. No island-effect on glucocorticoid levels for a rodent from a near-shore archipelago. PeerJ 2020; 8:e8590. [PMID: 32110493 PMCID: PMC7034373 DOI: 10.7717/peerj.8590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 01/17/2020] [Indexed: 11/20/2022] Open
Abstract
Island rodents are often larger and live at higher population densities than their mainland counterparts, characteristics that have been referred to as "island syndrome". Island syndrome has been well studied, but few studies have tested for island-mainland differences in stress physiology. We evaluated island syndrome within the context of stress physiology of white-footed mice (Peromyscus leucopus) captured from 11 islands and five mainland sites in Thousand Islands National Park, Ontario, Canada. Stress physiology was evaluated by quantifying corticosterone (a stress biomarker), the primary glucocorticoid in mice, from hair and its related metabolites from fecal samples. White-footed mice captured in this near-shore archipelago did not display characteristics of island syndrome, nor differences in levels of hair corticosterone or fecal corticosterone metabolites compared with mainland mice. We suggest that island white-footed mice experience similar degrees of stress in the Thousand Islands compared with the mainland. Although we did not find evidence of island syndrome or differences in glucocorticoid levels, we identified relationships between internal (sex, body mass) and external (season) factors and our hormonal indices of stress in white-footed mice.
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Affiliation(s)
- Nathan D Stewart
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario, Canada
| | | | - Gary Burness
- Department of Biology, Trent University, Peterborough, Ontario, Canada
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How does cognitive performance change in relation to seasonal and experimental changes in blood glucose levels? Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.10.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Season and sex have different effects on hematology and cytokines in striped hamsters (Cricetulus barabensis). J Comp Physiol B 2019; 190:87-100. [PMID: 31732779 DOI: 10.1007/s00360-019-01246-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 10/18/2019] [Accepted: 11/06/2019] [Indexed: 01/30/2023]
Abstract
Animals in the temperate zones face seasonal variations in environments and hence their immune responses change seasonally. In the current study, seasonal changes in hematological parameters and cytokines in striped hamsters (Cricetulus barabensis) were examined to test the winter immunoenhancement hypothesis, which states that immune function tends to increase in fall and winter compared with other seasons. Male and female hamsters were captured from the wild in the fall and winter of 2014 and in the spring and summer of 2015. Maximum body mass in both sexes and relative fatness in female hamsters occurred in the summer, indicating that body condition was the best during this season. All hematological parameters were not different between male and female hamsters, and were also not affected by the interaction of season and sex except neutrophil granulocytes (GRAN). Red blood cells (RBC) and haematocrit (PCV) were higher in the fall and winter, and hemoglobin concentration (HGB) was the highest in winter in hamsters compared with the spring and summer, implying that their oxygen-carrying capacity and oxygen affinity of the blood increased during these seasons. Compared with other seasons, the number of white blood cells (WBC) was higher in winter than in summer, intermediate granulocytes (MID), the percent of MID (MID%), GRAN and the percent of GRAN (GRAN%) were the highest in winter, which all supported the winter immunoenhancement hypothesis. However, the count of lymphocytes (LYMF) was the highest in spring, being inconsistent with this hypothesis. IL-2 levels, but not TNF-α, were influenced by seasons, sex and their interaction in hamsters. Regardless of sex, IL-4 titres were higher in spring and summer than in fall and winter in hamsters. INF-γ titres in male hamsters did not differ between the spring and summer, while its titres in female hamsters was lower in spring in contrast with winter and summer. Higher IL-2 and IL-4 levels during the breeding seasons might be crucial in controlling the increased possibilities of infections in these seasons. In summary, season and sex had disparate effects on different hematological profiles and the levels of cytokines in hamsters.
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Vuarin P, Pillay N, Schradin C. Elevated basal corticosterone levels increase disappearance risk of light but not heavy individuals in a long-term monitored rodent population. Horm Behav 2019; 113:95-102. [PMID: 31077709 DOI: 10.1016/j.yhbeh.2019.05.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 03/22/2019] [Accepted: 05/07/2019] [Indexed: 11/24/2022]
Abstract
According to the cort-fitness hypothesis, glucocorticoid levels correlate negatively with fitness. However, field studies found mixed support for this hypothesis, potentially because the association between glucocorticoids and fitness might depend on prevailing environmental conditions. Based on the long-term monitoring of a natural rodent population, we tested whether individuals with elevated corticosterone levels were more likely to disappear, accounting for individual condition and among-year variation in food availability, population density and predation pressure. We used basal corticosterone levels measured at the onset of the pre-breeding season in 331 African striped mice from six generations. While basal corticosterone levels were highly repeatable within individuals, between-individual variation was large. Survival analysis revealed that disappearance risk over the pre-breeding season increased with elevated basal corticosterone levels for light but not for heavy individuals. High levels of corticosterone may be more deleterious to smaller individuals (i.e. through allostatic overload), eventually increasing their mortality risk, and disappearance would represent actual death. An alternative non-exclusive explanation could be that high levels of corticosterone selectively trigger dispersal in light individuals, and disappearance would rather reflect their departure from the population. Although environmental conditions varied considerably among generations, none of the interactions between corticosterone and environmental variables were significant. Disappearance probability was positively correlated with both predation pressure and with food availability, a factor favoring dispersal. In sum, elevated basal corticosterone levels increased disappearance in light striped mice, either directly via reduced survival prospects and/or indirectly via dispersal.
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Affiliation(s)
- Pauline Vuarin
- University of the Witwatersrand, School of Animal, Plant and Environmental Sciences, 1 Jan Smuts Avenue, Braamfontein 2000, South Africa
| | - Neville Pillay
- University of the Witwatersrand, School of Animal, Plant and Environmental Sciences, 1 Jan Smuts Avenue, Braamfontein 2000, South Africa
| | - Carsten Schradin
- University of the Witwatersrand, School of Animal, Plant and Environmental Sciences, 1 Jan Smuts Avenue, Braamfontein 2000, South Africa; Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France.
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20
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Medger K, Bennett NC, Ganswindt SB, Ganswindt A, Hart DW. Changes in prolactin, cortisol and testosterone concentrations during queen succession in a colony of naked mole-rats (Heterocephalus glaber): a case study. Naturwissenschaften 2019; 106:26. [PMID: 31089819 DOI: 10.1007/s00114-019-1621-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 04/09/2019] [Accepted: 05/02/2019] [Indexed: 12/18/2022]
Abstract
Colonies of naked mole-rats (Heterocephalus glaber, NMRs) are characterised by an extreme skew in lifetime reproductive success with only one female and one to three male consorts in a colony. The rest of the individuals in a colony are reproductively suppressed and much research has been focussed on elucidating that mechanism. The dopamine system and prolactin have recently been implicated in the suppression of reproduction of subordinate NMRs. To investigate the changes in prolactin during the removal of an aged reproductive female (queen) and succession of a new queen, blood samples were collected during different stages of queen removal: before queen removal, after separation, but in olfactory contact with the queen and after the total removal of the queen. Further, plasma cortisol and testosterone concentrations were determined. The colony appeared unstable prior to queen removal as indicated by high concentrations of cortisol and testosterone and lack of successful breeding. A new queen succeeded the old queen whilst she was still in olfactory contact. The time preceding queen succession was characterised by high levels of aggression, the death of a number of individuals, high cortisol and testosterone and low prolactin concentrations. Once the older queen was removed entirely and the new queen had given birth, prolactin concentrations increased and cortisol and testosterone concentrations decreased in subordinate NMRs. The results suggest that low prolactin levels are associated with low reproductive suppression during times of colony instability due to the removal or death of a queen.
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Affiliation(s)
- Katarina Medger
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
| | - Nigel C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
- SARChI Chair of Mammal Behavioural Ecology and Physiology, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Stefanie B Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
- Department of Anatomy and Physiology, Faculty of Veterinary Science, Endocrine Research Laboratory, Private Bag X04, Onderstepoort, 0110, South Africa
| | - Andre Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
- Department of Anatomy and Physiology, Faculty of Veterinary Science, Endocrine Research Laboratory, Private Bag X04, Onderstepoort, 0110, South Africa
| | - Daniel W Hart
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
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Vera F, Antenucci CD, Zenuto RR. Different regulation of cortisol and corticosterone in the subterranean rodent Ctenomys talarum: Responses to dexamethasone, angiotensin II, potassium, and diet. Gen Comp Endocrinol 2019; 273:108-117. [PMID: 29782839 DOI: 10.1016/j.ygcen.2018.05.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 05/09/2018] [Accepted: 05/17/2018] [Indexed: 12/13/2022]
Abstract
When harmful environmental stimuli occur, glucocorticoids (GCs), cortisol and corticosterone are currently used to evaluate stress status in vertebrates, since their secretions are primarily associated to an increased activity of the hypothalamic-pituitaryadrenal (HPA) axis. To advance in our comprehension about GCs regulation, we evaluated the subterranean rodent Ctenomys talarum to assess cortisol and corticosterone response to (1) the negative feedback of the HPA axis using the dexamethasone (DEX) suppression test, (2) angiotensin II (Ang II), (3) potassium (K+) intake, and (4) different diets (vegetables, grasses, acute fasting). Concomitantly, several indicators of individual condition (body mass, neutrophil to lymphocyte ratio, blood glucose, triglycerides and hematocrit) were measured for diet treatments. Results confirm the effect of DEX on cortisol and corticosterone in recently captured animals in the field but not on corticosterone in captive animals. Data suggest that Ang II is capable of stimulating corticosterone, but not cortisol, secretion. Neither cortisol nor corticosterone were responsive to K+ intake. Cortisol levels increased in animals fed with grasses in comparison to those fed with vegetables while corticosterone levels were unaffected by diet type. Moreover, only cortisol responded to fasting. Overall, these results confirm that cortisol and corticosterone are not interchangeable hormones in C. talarum.
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Affiliation(s)
- Federico Vera
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
| | - C Daniel Antenucci
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
| | - Roxana R Zenuto
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
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Xu DL, Hu XK, Tian Y. Seasonal variations in cellular and humoral immunity in male striped hamsters ( Cricetulus barabensis). Biol Open 2018; 7:bio038489. [PMID: 30404899 PMCID: PMC6310883 DOI: 10.1242/bio.038489] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 10/15/2018] [Indexed: 12/18/2022] Open
Abstract
Animals in the non-tropical zone usually demonstrate seasonal variations in immune function, which is important for their survival. In the present study, seasonal changes in immunity in striped hamsters (Cricetulus barabensis) were investigated to test the winter immunoenhancement hypothesis. Male hamsters were captured from the wild in the fall and winter of 2014 and in the spring and summer of 2015. Body mass, body fat mass and blood glucose levels of the hamsters were all highest in the summer, whereas relative fatness and thymus mass had no seasonal changes. Spleen mass was highest in the fall and white blood cells and phytohaemagglutinin (PHA) response indicative of cellular immunity were lowest in the summer among the four seasons, which supports the winter immunoenhancement hypothesis. IgG and IgM titers were lowest in the fall, which was against this hypothesis. Body fat mass had no correlations with cellular and humoral immunity, suggesting it was not the reason for seasonal changes in cellular and humoral immunity in males. Leptin titers were higher in spring and summer than in fall and winter. No correlation between leptin and cellular and humoral immunity suggested that leptin did not mediate their seasonal changes. Similarly, corticosterone levels were also higher in spring and summer than in fall and winter, which correlated negatively with cellular immunity but positively with IgG levels. This result implied that corticosterone has a suppressive effect on cellular immunity and an enhancing effect on humoral immunity. In summary, distinct components of immune systems exhibited different seasonal patterns. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- De-Li Xu
- College of Life Sciences, Qufu Normal University, Qufu 273165, Shandong Province, China
| | - Xiao-Kai Hu
- College of Life Sciences, Qufu Normal University, Qufu 273165, Shandong Province, China
| | - Yufen Tian
- Library, Qufu Normal University, Qufu 273165, Shandong Province, China
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Schradin C, Vuarin P, Rimbach R. The neoteny-helper hypothesis: When to expect and when not to expect endocrine mechanisms to regulate allo-parental care? Physiol Behav 2018; 193:127-134. [DOI: 10.1016/j.physbeh.2017.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 12/06/2017] [Accepted: 12/06/2017] [Indexed: 11/15/2022]
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Seasonal variation in energy expenditure in a rodent inhabiting a winter-rainfall desert. J Comp Physiol B 2018; 188:877-888. [PMID: 29948157 DOI: 10.1007/s00360-018-1168-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 05/23/2018] [Accepted: 05/29/2018] [Indexed: 12/20/2022]
Abstract
Animals that spend more energy than they obtain risk entering allostatic overload, reducing survival and fitness. They are predicted to adjust their daily energy expenditure (DEE) during periods of food scarcity. Adjustments of DEE to changes in food availability have been well-studied in species in temperate zones during winter, but less so in species enduring seasonal droughts. Likely mechanisms regulating DEE involve adjustments of activity and maintenance metabolism. Species that experience seasonal droughts and changes in food availability, like the African striped mouse (Rhabdomys pumilio), are appropriate model organisms to study the regulation of seasonal changes of DEE. We quantified DEE using the 'doubly labelled water' method, measured resting metabolic rate (RMR), and concomitantly determined activity levels using all-day focal observations of 69 free-living striped mice in the cold moist season with high food availability and the hot dry season with low food availability. Striped mice decreased their DEE in the food scarce dry season using multiple mechanisms, especially reductions in RMR, and reduced overall physical activity. This was further facilitated passively by reduced thermoregulatory costs. Our study demonstrates that animals reduce DEE via active and passive mechanisms in food-restricted environments, and highlights that several environmental factors should be considered simultaneously when aiming to understand how animals cope with harsh environments.
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Zatra Y, Aknoun-Sail N, Kheddache A, Benmouloud A, Charallah S, Moudilou EN, Exbrayat JM, Khammar F, Amirat Z. Seasonal changes in plasma testosterone and cortisol suggest an androgen mediated regulation of the pituitary adrenal axis in the Tarabul's gerbil Gerbillus tarabuli (Thomas, 1902). Gen Comp Endocrinol 2018; 258:173-183. [PMID: 28811197 DOI: 10.1016/j.ygcen.2017.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/23/2017] [Accepted: 08/11/2017] [Indexed: 12/05/2022]
Abstract
In the desert gerbil Gerbillus tarabuli (Thomas, 1902), cortisol is the main glucocorticosteroid produced by the adrenal glands. Plasma cortisol concentrations show highest values when testosterone is reduced and lowest values during the breeding season which occurs from early winter to late spring. In order to specify the implication of testicular androgens in these corticosteroid seasonal variations we investigated the effects induced by gonadectomy performed during the breeding season on the pituitary adrenal axis. The animals collected in winter were assessed into three groups: sham-operated (Controls; n=13), gonadectomised (GDX; n=13) and testosterone replaced gonadectomised (GDX+T; n=13). Physiological replacement of testosterone enanthate (75µg/100gb.w./twice daily) was applied during one week, while GDX group received the vehicle (40µL sesame oil) alone. The right adrenal glands removed from euthanized animals were fixed for histomorphometry and androgen receptors (ARs) immunohistochemistry and the left ones were frozen with plasma samples until hormonal assays. Gonadectomy induces the enlargement of the adrenal cortex essentially due to that of zonae fasciculata (ZF) and reticularis (ZR) and perimedullary connective tissue which is abundant in the gerbil adrenals. The ARs immunostaining present at both cytoplasmic and nucleus level, is enhanced intensely in the ZR and moderately in the ZF and zona glomerulosa (ZG) cells. GDX group shows reduced plasma ACTH concentration (p=0.0126) by 61% despite the increase in cortisol concentration occurring both in plasma (+216%; p=0.0436) and adrenal tissue (+117%; p=0.0348). Plasma aldosterone is also enhanced significantly (p=0.0147) by 189% but androstenedione synthesis increased in adrenal tissue (p=0.0459) by 65% instead a decrease at circulatory level (p=0.0355) by 58% due to lack of testicular origin. So, testosterone deprivation activates corticosteroidogenesis also evidenced by the adrenal structure changes and the gonadectomy-induced increase in the plasma cholesterol. All of the gonadectomy-induced responses are reversible after physiological testosterone replacement. We conclude that the assessment of circulating adrenocorticotropic hormone (ACTH) concentrations together with cortisol levels essentially, reflecting the hypothalamic-pituitary adrenal (HPA) axis feedback loop control during the annual endogenous changes of testosterone secretion, represents a well-adapted response of this desert species living in an extreme environment.
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Affiliation(s)
- Yamina Zatra
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Naouel Aknoun-Sail
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Arezki Kheddache
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Abdelouafi Benmouloud
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Salima Charallah
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Elara N Moudilou
- Université de Lyon, UMRS 449, Laboratoire de Biologie Générale, Université Catholique de Lyon, Reproduction et Développement Comparé, EPHE, 10 place des archives, 69288 Lyon Cedex 02, France.
| | - Jean-Marie Exbrayat
- Université de Lyon, UMRS 449, Laboratoire de Biologie Générale, Université Catholique de Lyon, Reproduction et Développement Comparé, EPHE, 10 place des archives, 69288 Lyon Cedex 02, France.
| | - Farida Khammar
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
| | - Zaina Amirat
- Université des Sciences et de la Technologie Houari Boumediene (USTHB), Laboratoire de recherche sur les zones arides (LRZA), Faculté des Sciences Biologiques, BP 32, El-Alia, 16111 ou BP 44, Alger Gare, 16000, DZ, Algeria.
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Boonstra R, Dušek A, Lane JE, Boutin S. When the ball is in the female's court: How the scramble-competition mating system of the North American red squirrel has shaped male physiology and testosterone dynamics. Gen Comp Endocrinol 2017. [PMID: 28648995 DOI: 10.1016/j.ygcen.2017.06.016] [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] [Indexed: 10/19/2022]
Abstract
Male reproductive success in most mammals is determined by their success in direct inter-male competition through aggression and conflict, resulting in female-defense mating systems being predominant. This is linked to male testosterone levels and its dynamics. However, in certain environments, a scramble-competition mating system has evolved, where female reproductive behavior takes precedence and male testosterone dynamics are unlikely to be related to inter-male competition. We studied the North American red squirrel (Tamiasciurus hudsonicus), a species with a well-established scramble-competition system. Using an ACTH hormonal challenge protocol as a proxy for competitive interactions, we compared the testosterone dynamics in breeding males in late winter with that in nonbreeding males in late spring in the Yukon. To gain an integrated picture of their physiological state, we also assessed changes in their stress response, body mass, energy mobilization, and indices of immune function. Testosterone levels at the base bleed were high in breeding males (2.72ng/mL) and virtually absent in non-breeding males (0.04ng/mL). Breeding males were in better condition (heavier body mass, higher hematocrit, and higher erythrocytes), had higher indices of immune function (neutrophil:lymphocyte ratio), but a similar ability to mobilize energy (glucose) compared with non-breeding males. Though total cortisol was higher in non-breeding males, free cortisol was twice as high in breeding males as their corticosteroid binding globulin levels were half as high. In response to the ACTH challenge, testosterone levels in breeding males declined 49% over the first hour and increased 36% over the next hour; in non-breeding males levels showed no change. Free cortisol increased only modestly (26% in breeding males; 23% in non-breeding males). Glucose levels changed similarly in breeding and nonbreeding males, declining for the first 30min and then increasing for the next 60min. Thus, testosterone and components of the stress axis function in a profoundly different manner in male red squirrels than in males of mammals with female-defense mating systems. There are four probable interrelated reasons for these adaptations in male red squirrels: the marginal benefits of each mating, the constraints of mate searching away from their own resource-based territories, energy mobilization in a harsh environment, and a long life span.
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Affiliation(s)
- Rudy Boonstra
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada.
| | - Adam Dušek
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada; Department of Ethology, Institute of Animal Science, Praha CZ-104 00, Czech Republic
| | - Jeffrey E Lane
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada; Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Stan Boutin
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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Hayes LD, Ebensperger LA, Kelt DA, Meserve PL, Pillay N, Viblanc VA, Schradin C. Long-term field studies on rodents. J Mammal 2017. [DOI: 10.1093/jmammal/gyw180] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Vera F, Zenuto R, Antenucci CD. Expanding the actions of cortisol and corticosterone in wild vertebrates: A necessary step to overcome the emerging challenges. Gen Comp Endocrinol 2017; 246:337-353. [PMID: 28109824 DOI: 10.1016/j.ygcen.2017.01.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 11/14/2016] [Accepted: 01/02/2017] [Indexed: 11/25/2022]
Abstract
We conducted a review of scientific articles published between 2000 and 2014 and evaluated how frequently various aspects of cortisol and corticosterone (CORT) actions have been considered in studies on wild vertebrates. Results show that (1) the notion that CORT are stress-responsive hormones is central in our theoretical frameworks and it is reflected by the fact that several articles refer to CORT as "stress hormones". (2) The large majority of studies do not contemplate the possibility of decrease and no change in CORT levels in response to chronic stressors. (3) Our ideas about CORT actions on energy balance are slanted towards the mobilization of energy, though there are several studies considering -and empirically addressing- CORT's orexigenic actions, particularly in birds. (4) The roles of CORT in mineral-water balance, though widely documented in the biomedical area, are virtually ignored in the literature about wild vertebrates, with the exception of studies in fish. (5) Adrenocorticotropic hormone (ACTH) independent regulation of CORT secretion is also very scarcely considered. (6) The preparative, permissive, suppressive and stimulatory actions of CORT, as described by Sapolsky et al. (2000), are not currently considered by the large majority of authors. We include an extension of the Preparative Hypothesis, proposing that the priming effects of baseline and stress-induced CORT levels increase the threshold of severity necessary for subsequent stimuli to become stressors. Studies on animal ecology and conservation require integration with novel aspects of CORT actions and perspectives developed in other research areas.
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Affiliation(s)
- Federico Vera
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
| | - Roxana Zenuto
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
| | - C Daniel Antenucci
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.
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Trade-offs between reproduction and health in free-ranging African striped mice. J Comp Physiol B 2017; 187:625-637. [DOI: 10.1007/s00360-016-1054-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 11/07/2016] [Accepted: 11/29/2016] [Indexed: 01/09/2023]
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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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Personality predicts the responses to environmental enrichment at the group but not within-groups in stereotypic African striped mice, Rhabdomys dilectus. Appl Anim Behav Sci 2016. [DOI: 10.1016/j.applanim.2016.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Rimbach R, Willigenburg R, Schoepf I, Yuen CH, Pillay N, Schradin C. Young But Not Old Adult African Striped Mice Reduce Their Activity in the Dry Season When Food Availability is Low. Ethology 2016. [DOI: 10.1111/eth.12527] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rebecca Rimbach
- School of Animal, Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
| | - Remco Willigenburg
- School of Animal, Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
- HAS Den Bosch; University of Applied Sciences; Den Bosch The Netherlands
| | - Ivana Schoepf
- School of Animal, Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
| | - Chi Hang Yuen
- School of Animal, Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
| | - Neville Pillay
- School of Animal, Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
| | - Carsten Schradin
- School of Animal, Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
- IPHC; UNISTRA; CNRS; Strasbourg France
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Schoepf I, Pillay N, Schradin C. The pathophysiology of survival in harsh environments. J Comp Physiol B 2016; 187:183-201. [DOI: 10.1007/s00360-016-1020-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 06/16/2016] [Accepted: 07/09/2016] [Indexed: 12/20/2022]
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Changing winter conditions in the boreal forest: the effects of fluctuating temperature and predation risk on activity and physiological stress level in bank voles. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2165-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Maille A, Schradin C. Ecophysiology of cognition: How do environmentally induced changes in physiology affect cognitive performance? Biol Rev Camb Philos Soc 2016; 92:1101-1112. [PMID: 27020603 DOI: 10.1111/brv.12270] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 02/29/2016] [Accepted: 03/01/2016] [Indexed: 12/29/2022]
Abstract
Cognitive performance is based on brain functions, which have energetic demands and are modulated by physiological parameters such as metabolic hormones. As both environmental demands and environmental energy availability change seasonally, we propose that cognitive performance in free-living animals might also change seasonally due to phenotypic plasticity. This is part of an emerging research field, the 'ecophysiology of cognition': environmentally induced changes in physiological traits, such as blood glucose and hormone levels, are predicted to influence cognitive performance in free-living animals. Energy availability for the brain might change, and as such cognition, with changing energetic demands (e.g. reproduction) and changes of energy availability in the environment (e.g. winter, drought). Individuals spending more energy than they can currently obtain from their environment (allostatic overload type I) are expected to trade off energy investment between cognition and other life-sustaining processes or even reproduction. Environmental changes reducing energy availability might thus impair cognition. However, selection pressures such as predation risk, mate choice or social demands may act on the trade-off between energy saving and cognition. We assume that different environmental conditions can lead to three different trade-off outcomes: cognitive impairment, resilience or enhancement. Currently we cannot understand these trade-offs, because we lack information about changes in cognitive performance due to seasonal changes in energy availability and both the resulting changes in homeostasis (for example, blood glucose levels) and the associated changes in the mechanisms of allostasis (for example, hormone levels). Additionally, so far we know little about the fitness consequences of individual variation in cognitive performance. General cognitive abilities, such as attention and associative learning, might be more important in determining fitness than complex and specialized cognitive abilities, and easier to use for comparative study in a large number of species. We propose to study seasonal changes in cognitive performance depending on energy availability in populations facing different predation risks, and the resulting fitness consequences.
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Affiliation(s)
- Audrey Maille
- IPHC-DEPE, Université de Strasbourg, Strasbourg, 67087, France.,CNRS, UMR7178, Strasbourg, 67087, France.,School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits, 2050, South Africa.,UMR 7206 Eco-anthropologie et Ethnobiologie, Muséum National d'Histoire Naturelle, site du Musée de l'Homme, 17 place du trocadéro, Paris, 75016, France.,Département des Jardins Botaniques et Zoologiques, Muséum National d'Histoire Naturelle, 57 rue Cuvier, Paris, 75005, France
| | - Carsten Schradin
- IPHC-DEPE, Université de Strasbourg, Strasbourg, 67087, France.,CNRS, UMR7178, Strasbourg, 67087, France.,School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits, 2050, South Africa.,University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, F-67083, France
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Fletcher QE, Dantzer B, Boonstra R. The impact of reproduction on the stress axis of free-living male northern red backed voles (Myodes rutilus). Gen Comp Endocrinol 2015; 224:136-47. [PMID: 26188715 DOI: 10.1016/j.ygcen.2015.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 07/05/2015] [Accepted: 07/14/2015] [Indexed: 11/29/2022]
Abstract
Activation of the hypothalamic-pituitary-adrenal (HPA) axis culminates in the release of glucocorticoids (henceforth CORT), which have wide-reaching physiological effects. Three hypotheses potentially explain seasonal variation in CORT. The enabling hypothesis predicts that reproductive season CORT exceeds post-reproductive season CORT because CORT enables reproductive investment. The inhibitory hypothesis predicts the opposite because CORT can negatively affect reproductive function. The costs of reproduction hypothesis predicts that HPA axis condition declines over and following the reproductive season. We tested these hypotheses in wild male red-backed voles (Myodes rutilus) during the reproductive and post-reproductive seasons. We quantified CORT levels in response to restraint stress tests consisting of three blood samples (initial, stress-induced, and recovery). Mineralocorticoid (MR) and glucocorticoid (GR) receptor mRNA levels in the brain were also quantified over the reproductive season. Total CORT (tCORT) in the initial and stress-induced samples were greater in the post-reproductive than in the reproductive season, which supported the inhibitory hypothesis. Conversely, free CORT (fCORT) did not differ between the reproductive and post-reproductive seasons, which was counter to both the enabling and inhibitory hypotheses. Evidence for HPA axis condition decline in CORT as well as GR and MR mRNA over the reproductive season (i.e. costs of reproduction hypothesis) was mixed. Moreover, all of the parameters that showed signs of declining condition over the reproductive season did not also show signs of declining condition over the post-reproductive season suggesting that the costs resulting from reproductive investment had subsided. In conclusion, our results suggest that different aspects of the HPA axis respond differently to seasonal changes and reproductive investment.
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Affiliation(s)
- Quinn E Fletcher
- Centre for the Neurobiology Stress, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada.
| | - Ben Dantzer
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Rudy Boonstra
- Centre for the Neurobiology Stress, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada.
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37
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Arginine vasopressin in brains of free ranging striped mouse males following alternative reproductive tactics. J ETHOL 2015. [DOI: 10.1007/s10164-015-0436-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Hill DL, Pillay N, Schradin C. Alternative reproductive tactics in female striped mice: Solitary breeders have lower corticosterone levels than communal breeders. Horm Behav 2015; 71:1-9. [PMID: 25828632 DOI: 10.1016/j.yhbeh.2015.03.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 03/16/2015] [Accepted: 03/23/2015] [Indexed: 10/23/2022]
Abstract
Alternative reproductive tactics (ARTs), where members of the same sex and population show distinct reproductive phenotypes governed by decision-rules, have been well-documented in males of many species, but are less well understood in females. The relative plasticity hypothesis (RPH) predicts that switches between plastic ARTs are mediated by changes in steroid hormones. This has received much support in males, but little is known about the endocrine control of female ARTs. Here, using a free-living population of African striped mice (Rhabdomys pumilio) over five breeding seasons, we tested whether females following different tactics differed in corticosterone and testosterone levels, as reported for male striped mice using ARTs, and in progesterone and oestrogen, which are important in female reproduction. Female striped mice employ three ARTs: communal breeders give birth in a shared nest and provide alloparental care, returners leave the group temporarily to give birth, and solitary breeders leave to give birth and do not return. We expected communal breeders and returners to have higher corticosterone, owing to the social stress of group-living, and lower testosterone than solitary breeders, which must defend territories alone. Solitary breeders had lower corticosterone than returners and communal breeders, as predicted, but testosterone and progesterone did not differ between ARTs. Oestrogen levels were higher in returners (measured before leaving the group) than in communal and solitary breeders, consistent with a modulatory role. Our study demonstrates hormonal differences between females following (or about to follow) different tactics, and provides the first support for the RPH in females.
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Affiliation(s)
- Davina L Hill
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa.
| | - Neville Pillay
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa.
| | - Carsten Schradin
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa; Université de Strasbourg, IPHC-DEPE, 23 rue Becquerel 67087 Strasbourg, France; CNRS, UMR7178, 67087 Strasbourg, France; Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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Nel K, Rimbach R, Pillay N. Dietary protein influences the life-history characteristics across generations in the African striped mouseRhabdomys. ACTA ACUST UNITED AC 2015; 323:97-108. [DOI: 10.1002/jez.1903] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/19/2014] [Accepted: 10/14/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Kerith Nel
- School of Animal; Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
| | - Rebecca Rimbach
- School of Animal; Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
| | - Neville Pillay
- School of Animal; Plant & Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
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Schoepf I, Schmohl G, König B, Pillay N, Schradin C. Manipulation of population density and food availability affects home range sizes of African striped mouse females. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2014.10.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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41
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Raynaud J, Schradin C. Corticosterone Levels Correlate With Alloparental Care in a Sex-Dependent Manner in African Striped Mice,Rhabdomys pumilio. Ethology 2014. [DOI: 10.1111/eth.12317] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julien Raynaud
- Institute of Evolutionary Biology and Environmental Studies; University of Zurich; Zurich Switzerland
| | - Carsten Schradin
- IPHC-DEPE; Université de Strasbourg; Strasbourg France
- CNRS; Strasbourg France
- School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
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Schradin C, Raynaud J, Arrivé M, Blanc S. Leptin levels in free ranging striped mice (Rhabdomys pumilio) increase when food decreases: the ecological leptin hypothesis. Gen Comp Endocrinol 2014; 206:139-45. [PMID: 24992023 DOI: 10.1016/j.ygcen.2014.06.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 06/13/2014] [Accepted: 06/21/2014] [Indexed: 11/29/2022]
Abstract
Leptin is a hormone informing the body about its fat stores, reducing appetite and foraging and as such reducing fattening of individuals. In laboratory rodents, leptin secretion is highly correlated to the amount of adipose tissue. We compared this to the alternative ecological leptin hypothesis, which based on the behavioural effects of leptin predicts that leptin levels are disassociated from adipose tissue when fattening is of evolutionary advantage to survive coming periods of low food availability. Studying a species that has to survive a dry season with low food availability, we tested the ecological leptin hypothesis, predicting low leptin levels when food availability and thus adiposity is high promoting foraging and fattening, but high leptin levels in the seasons of low food availability, reducing energetic costs due to foraging. We measured leptin levels in 154 samples of free living African striped mice (Rhabdomys pumilio). Striped mice gain significant body mass during the moist season to survive the following dry season with low food availability. We found a strong seasonal effect, with higher leptin levels in the dry season with low food availability, which was in contrast to the hypothesis deriving from studies on laboratory rodents, but in agreement with ecological leptin hypothesis: leptin levels remained low in the period of high food availability, allowing fattening, but increased during periods of low food availability, possibly suppressing energetically costly foraging in an environment where foraging success would have been very low. Leptin correlated significantly and negatively with testosterone levels, and high testosterone levels in the moist season could explain why leptin levels were low even though food availability was high. However, analysing samples from an experimental laboratory study where testosterone levels were increased via implants found no support for a suppressive role of testosterone on leptin. In sum, our study indicates that in a species with seasonal fattening, leptin levels might be uncoupled from the amount of adipose tissue.
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Affiliation(s)
- Carsten Schradin
- Université de Strasbourg, IPHC-DEPE, 23 rue Becquerel, 67087 Strasbourg, France; CNRS, UMR 7178, 67087 Strasbourg, France; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Julien Raynaud
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Mathilde Arrivé
- Université de Strasbourg, IPHC-DEPE, 23 rue Becquerel, 67087 Strasbourg, France; CNRS, UMR 7178, 67087 Strasbourg, France
| | - Stéphane Blanc
- Université de Strasbourg, IPHC-DEPE, 23 rue Becquerel, 67087 Strasbourg, France; CNRS, UMR 7178, 67087 Strasbourg, France
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43
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Androgen receptor-mediated regulation of adrenocortical activity in the sand rat, Psammomys obesus. J Comp Physiol B 2014; 184:1055-63. [PMID: 25179180 DOI: 10.1007/s00360-014-0859-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 08/13/2014] [Accepted: 08/19/2014] [Indexed: 01/19/2023]
Abstract
The wild sand rat, Psammomys obesus, displays seasonal variations in adrenocortical activity that parallel those of testicular activity, indicating functional cross-talk between the hypothalamo-pituitary-adrenal and hypothalamo-pituitary-gonadal axes. In the present study, we examined androgen receptor (AR)-mediated actions of testicular steroids in the regulation of adrenocortical function in the sand rat. Specifically, we examined the expression of AR in the adrenal cortex, as well as adrenal apoptosis in male sand rats that had been surgically castrated or castrated and supplemented with testosterone; biochemical indices of adrenocortical function and hormone profiles were also measured. Orchiectomy was followed by an increase in adrenocorticotropic hormone secretion from the anterior pituitary and subsequently, increased adrenocortical activity; the latter was evidenced by orchiectomy-induced increases in the adrenal content of cholesterol and lipids as well as adrenal hypertrophy (seen as an elevation of the RNA/DNA ratio). Further, androgen deprivation respectively up- and downregulated the incidence of apoptosis within the glucocorticoid-producing zona fasciculata and sex steroid-producing zona reticularis. Interestingly, orchiectomy resulted in increased expression of AR in the zona fasciculata. All of the orchiectomy-induced cellular and biochemical responses were reversible after testosterone substitution therapy. Together, these data suggest that adrenocortical activity in the sand rat is seasonally modulated by testicular androgens that act through AR located in the adrenal cortex itself.
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Schoepf I, Schradin C. Arginine vasopressin plasma levels change seasonally in African striped mice but do not differ between alternative reproductive tactics. Gen Comp Endocrinol 2014; 204:43-8. [PMID: 24842715 DOI: 10.1016/j.ygcen.2014.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/30/2014] [Accepted: 05/02/2014] [Indexed: 11/20/2022]
Abstract
Arginine vasopressin (AVP) is an important hormone for osmoregulation, while as a neuropeptide in the brain it plays an important role in the regulation of social behaviors. Dry habitats are often the home of obligately sociable species such as meerkats and Damaraland mole-rats, leading to the hypothesis that high plasma AVP levels needed for osmoregulation might be associated with the regulation of social behavior. We tested this in a facultative sociable species, the African striped mouse (Rhabdomys pumilio). During the moist breeding season, both solitary- and group-living reproductive tactics occur in this species, which is obligatory sociable in the dry season. We collected 196 plasma samples from striped mice following different reproductive tactics both during the moist and the dry season. Solitary mice did not have lower AVP levels than sociable mice, rejecting the hypothesis that peripheral AVP is involved in the regulation of alternative reproductive tactics. However, we found significantly higher AVP levels during the dry season, with AVP levels correlated with the abundance of food plants, the main source of water for striped mice. Plasma AVP levels were not correlated with testosterone or corticosterone levels. Our study underlines the important role that AVP plays in osmoregulation, particularly for a free ranging mammal living under harsh arid conditions.
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Affiliation(s)
- Ivana Schoepf
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Carsten Schradin
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa; Université de Strasbourg, IPHC-DEPE, 23 rue Becquerel, 67087 Strasbourg, France; CNRS, UMR7178, 67087 Strasbourg, France.
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45
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Aguilar F, Rödel HG, Vázquez J, Nicolas L, Rodríguez-Martínez L, Bautista A, Martínez-Gómez M. Seasonal changes in testosterone levels in wild Mexican cottontails Sylvilagus cunicularius. Mamm Biol 2014. [DOI: 10.1016/j.mambio.2014.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Navarro-Castilla Á, Mata C, Ruiz-Capillas P, Palme R, Malo JE, Barja I. Are motorways potential stressors of roadside wood mice (Apodemus sylvaticus) populations? PLoS One 2014; 9:e91942. [PMID: 24637740 PMCID: PMC3956862 DOI: 10.1371/journal.pone.0091942] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 02/14/2014] [Indexed: 11/18/2022] Open
Abstract
Linear infrastructures represent one of the most important human impacts on natural habitats and exert several effects on mammal populations. Motorways are recognized as a major cause of habitat fragmentation and degradation and of biodiversity loss. However, it is unknown whether motorways lead to increased physiological stress reactions in wild animal populations. We analysed faecal corticosterone metabolites (FCM) in wild populations of wood mice (Apodemus sylvaticus) living in a well-preserved Mediterranean agro-pastoral woodland at different distances (verge, 500 m and 1000 m) from the AP-51 motorway in Spain. Wood mice were captured with Sherman live traps, and fresh faecal samples from 424 individuals were collected and analyzed in the laboratory. The quantification of FCM was performed by a 5α-pregnane-3β,11β, 21-triol-20-one enzyme immunoassay. Results showed that females had higher FCM levels than males, and these levels were higher in breeding females. In addition, FCM levels were positively correlated with body weight of individuals. Wood mice captured where cattle were present showed higher FCM levels than individuals living where cattle were not detected. FCM levels were higher in non-breeding individuals living close to the motorway compared with FCM levels in those individuals captured further from the motorway. This is the first study showing evidence of the motorways' impact on physiological stress reactions in wild wood mice populations. Understanding how free-living animals are influenced by human interventions could help to understand other subtle changes observed in wild animal populations. Since mice are used world-wide as research models these results could open new perspectives testing human influence on the natural environment and trade-offs of species in degraded ecosystems.
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Affiliation(s)
| | - Cristina Mata
- Department of Ecology, Terrestrial Ecology Group, University Autónoma of Madrid, Madrid, Spain
| | - Pablo Ruiz-Capillas
- Dirección de Innovación y Sostenibilidad, Obrascón Huarte Lain, S.A., Madrid, Spain
| | - Rupert Palme
- Department of Biomedical Sciences/Biochemistry, University of Veterinary Medicine, Vienna, Austria
| | - Juan E. Malo
- Department of Ecology, Terrestrial Ecology Group, University Autónoma of Madrid, Madrid, Spain
| | - Isabel Barja
- Department of Biology, Zoology Unit, University Autónoma of Madrid, Madrid, Spain
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47
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Schradin C, Larke RH, Bales KL. Growing up in the family or growing up alone influences behavior and hormones, but not arginine vasopressin receptor 1a expression in male African striped mice. Physiol Behav 2014; 129:205-13. [PMID: 24631307 DOI: 10.1016/j.physbeh.2014.02.060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 01/16/2014] [Accepted: 02/21/2014] [Indexed: 11/17/2022]
Abstract
In many species males display alternative reproductive tactics (ARTs). While males of different tactics differ behaviorally in the field, it is often not known whether these behavioral differences would also occur under standardized laboratory conditions, nor how ARTs are regulated by the brain. In the present study we kept male African striped mice (Rhabdomys pumilio) in captivity either in family groups or solitary, to mimic ARTs observed in the field. This allowed us to study these males behaviorally under standardized conditions, to replicate physiological findings from the field, and to study the expression of the arginine vasopressin 1a receptor (AVPR1a) in their brains. Changes in either peptide release or receptor expression (or both) might regulate ARTs with differential timelines, with peptide secretion being faster than receptor expression. As observed in the field, family living males had higher corticosterone but lower testosterone levels than singly housed males. Surprisingly, singly housed males were less aggressive while at the same time having higher testosterone levels. We found no differences in AVPR1a expression. In a previous study it was shown that singly housed males have higher levels of AVP stored in their brain, which potentially could be secreted when the social situation changes, for example to establish social bonds. Our study on AVPR1a suggests the hypothesis that, given that the receptor distribution and expression of singly housed males do not differ from that of family-living males, the brains of singly-housed males have a similar capacity to be responsive to AVP when given the chance to interact socially.
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Affiliation(s)
- Carsten Schradin
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa; Université de Strasbourg, IPHC-DEPE, 23 rue Becquerel, 67087 Strasbourg, France; CNRS, UMR7178, 67087 Strasbourg, France.
| | - Rebecca H Larke
- Department of Psychology, University of California, Davis, CA 95616, USA
| | - Karen L Bales
- Department of Psychology, University of California, Davis, CA 95616, USA
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Raynaud J, Schradin C. Experimental increase of testosterone increases boldness and decreases anxiety in male African striped mouse helpers. Physiol Behav 2014; 129:57-63. [PMID: 24534177 DOI: 10.1016/j.physbeh.2014.02.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 07/25/2013] [Accepted: 02/04/2014] [Indexed: 11/25/2022]
Abstract
Males of many species can adjust their behaviors to environmental conditions by changing reproductive tactics. Testosterone surges in adult breeding males typically inhibit the expression of paternal care while facilitating the expression of aggression during environmental changes. Similarly, in non-breeding philopatric males of cooperatively breeding species, up-regulation of testosterone may inhibit alloparental care while facilitating dispersal, i.e. males might become bolder and more explorative. We tested this hypothesis in philopatric male African striped mice, Rhabdomys pumilio. Striped mouse males can either remain in their natal groups providing alloparental care or they can disperse seeking mating opportunities. Compared to philopatric males, dispersed males typically show higher testosterone levels and lower corticosterone levels, and more aggression toward pups and same sex conspecifics. We experimentally increased the testosterone levels of the philopatric males kept in their family groups when pups were present. Testosterone-treated males did not differ significantly from control males in alloparental care and in aggression toward same-sex conspecifics. Compared to the control males, testosterone treated males were bolder, more active, and less anxious; they also showed lower corticosterone levels. The philopatric males were sensitive to our testosterone treatment for dispersal- and anxiety-like behavior but insensitive for social behaviors. Our results suggest a role of testosterone in dispersal.
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Affiliation(s)
- Julien Raynaud
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| | - Carsten Schradin
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Université de Strasbourg, IPHC-DEPE, France; CNRS, UMR7178, 67087 Strasbourg, France; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa
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Navarro-Castilla Á, Barja I, Olea PP, Piñeiro A, Mateo-Tomás P, Silván G, Illera JC. Are degraded habitats from agricultural crops associated with elevated faecal glucocorticoids in a wild population of common vole (Microtus arvalis)? Mamm Biol 2014. [DOI: 10.1016/j.mambio.2013.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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50
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Jack KM, Schoof VAM, Sheller CR, Rich CI, Klingelhofer PP, Ziegler TE, Fedigan L. Hormonal correlates of male life history stages in wild white-faced capuchin monkeys (Cebus capucinus). Gen Comp Endocrinol 2014; 195:58-67. [PMID: 24184868 PMCID: PMC3894788 DOI: 10.1016/j.ygcen.2013.10.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 10/14/2013] [Accepted: 10/21/2013] [Indexed: 11/24/2022]
Abstract
Much attention has been paid to hormonal variation in relation to male dominance status and reproductive seasonality, but we know relatively little about how hormones vary across life history stages. Here we examine fecal testosterone (fT), dihydrotestosterone (fDHT), and glucocorticoid (fGC) profiles across male life history stages in wild white-faced capuchins (Cebus capucinus). Study subjects included 37 males residing in three habituated social groups in the Área de Conservacíon Guanacaste, Costa Rica. Male life history stages included infant (0 to <12months; N=3), early juvenile (1 to <3years; N=10), late juvenile (3 to <6years; N=9), subadult (6 to <10years; N=8), subordinate adult (⩾10years; N=3), and alpha adult (⩾10years; N=4, including one recently deposed alpha). Life history stage was a significant predictor of fT; levels were low throughout the infant and juvenile phases, doubled in subadult and subordinate adults, and were highest for alpha males. Life history stage was not a significant predictor of fDHT, fDHT:fT, or fGC levels. Puberty in white-faced capuchins appears to begin in earnest during the subadult male phase, indicated by the first significant rise in fT. Given their high fT levels and exaggerated secondary sexual characteristics, we argue that alpha adult males represent a distinctive life history stage not experienced by all male capuchins. This study is the first to physiologically validate observable male life history stages using patterns of hormone excretion in wild Neotropical primates, with evidence for a strong association between fT levels and life history stage.
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Affiliation(s)
- Katharine M Jack
- Tulane University, Department of Anthropology, 101 Dinwiddie Hall, 6823 St. Charles Ave., New Orleans, LA 70118, USA.
| | - Valérie A M Schoof
- Tulane University, Department of Anthropology, 101 Dinwiddie Hall, 6823 St. Charles Ave., New Orleans, LA 70118, USA.
| | - Claire R Sheller
- Tulane University, Department of Anthropology, 101 Dinwiddie Hall, 6823 St. Charles Ave., New Orleans, LA 70118, USA.
| | - Catherine I Rich
- Tulane University, Department of Anthropology, 101 Dinwiddie Hall, 6823 St. Charles Ave., New Orleans, LA 70118, USA.
| | - Peter P Klingelhofer
- Tulane University, Department of Anthropology, 101 Dinwiddie Hall, 6823 St. Charles Ave., New Orleans, LA 70118, USA.
| | - Toni E Ziegler
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1223 Capitol Court, Madison, WI 53715, USA.
| | - Linda Fedigan
- University of Calgary, Department of Anthropology, 2500 University Drive N.W., Calgary, AB T2N 1N4, Canada.
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