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Stead SM, Edwards PD, Persad R, Boonstra R, Teichroeb JA, Palme R, Bowman J. Coping with extreme free cortisol levels: Seasonal stress axis changes in sympatric North American flying squirrels. Gen Comp Endocrinol 2024; 349:114467. [PMID: 38342330 DOI: 10.1016/j.ygcen.2024.114467] [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: 12/07/2023] [Revised: 01/18/2024] [Accepted: 02/03/2024] [Indexed: 02/13/2024]
Abstract
Most environments exhibit predictable yearly changes, permitting animals to anticipate them. The hypothalamic-pituitary-adrenal (HPA) axis is a key physiological pathway that enables animals to cope with such changes. Monitoring glucocorticoid (the end products of the HPA axis) levels in wild animals throughout the year can improve our understanding of how this pathway responds to different conditions. For this study, we collected 18 months of data on two species of North American flying squirrels (Glaucomys sabrinus and G. volans) living in a southern Ontario forest where temperature and food availability fluctuate dramatically throughout the year. These squirrels are active year-round, nest communally, and rely on scatter hoarded foods in the winter months. Flying squirrels have extremely high levels of free plasma cortisol relative to other mammals, but it is unknown how these levels are affected by environmental and reproductive factors. For both species, our goals were to (1) validate an enzyme immunoassay (EIA) to measure their fecal glucocorticoid metabolite (FGM) concentrations and (2) assess yearly differences, seasonal changes, and the influence of sex, reproduction, and ambient temperature on FGM concentrations in each species. In the lab, we successfully validated the use of antibody 5α-pregnane-3β, 11β, 21-triol-20-one EIA for FGM analysis in both species. In the field, neither sex nor reproductive status (breeding condition or not) were linked to FGM concentrations in either species. FGM concentrations were higher in autumn compared to the spring and summer. There were no other seasonal differences. We discuss possible explanations for the autumn peak in FGM concentrations (increased energy expenditure and social nesting changes), as well as outline possible avenues for future research. Understanding how individuals and populations respond to environmental change is a critical goal in evolutionary ecology, particularly in the context of a rapidly changing Anthropocene.
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Affiliation(s)
- Samantha M Stead
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada.
| | - Phoebe D Edwards
- Department of Psychology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Rebekah Persad
- Environmental & Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario, Canada
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Julie A Teichroeb
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Rupert Palme
- Department of Biological Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Jeff Bowman
- Environmental & Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario, Canada; Wildlife Research & Monitoring Section, Ontario Ministry of Natural Resources & Forestry, Trent University, Peterborough, Ontario, Canada
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Witczak LR, Arias Del Razo R, Baxter A, Conley AJ, Cotterman R, Dufek M, Goetze LR, Lau AR, Mendoza SP, Savidge LE, Bales KL. Relationships between cortisol and urinary androgens in female titi monkeys (Plecturocebus cupreus). Gen Comp Endocrinol 2021; 314:113927. [PMID: 34653435 PMCID: PMC9250648 DOI: 10.1016/j.ygcen.2021.113927] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 10/04/2021] [Accepted: 10/09/2021] [Indexed: 01/16/2023]
Abstract
Steroid hormones are critical to the regulation of sociosexual behavior. Their role in the formation of pair bonds is complicated by the relative scarcity of this social system in mammals, as well as species and taxonomic differences in endocrine systems. In the present study, we experimentally manipulated the hypothalamic-pituitary-adrenal axis in female titi monkeys (Plecturocebus cupreus), a neotropical monkey studied for its strong, selective pair bonds. We validated an assay for plasma and urinary cortisol in this species, showing a strong suppression of cortisol following dexamethasone injection, and a significant but somewhat blunted response to adrenocorticotrophin hormone (ACTH) stimulation. Urinary androgens did not change in response to dexamethasone or ACTH. Plasma and urinary cortisol were moderately correlated, whereas urinary cortisol and androgens were only correlated when extreme cortisol values were included. In this study, we laid groundwork for studying the role of glucocorticoids and androgens (and eventually, their interactions with peptides) in the behavioral endocrinology of pair bonds in female titi monkeys.
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Affiliation(s)
- Lynea R Witczak
- Department of Psychology, University of California, Davis, United States; California National Primate Research Center, University of California, Davis, United States
| | - Rocío Arias Del Razo
- Department of Psychology, University of California, Davis, United States; California National Primate Research Center, University of California, Davis, United States
| | - Alexander Baxter
- Department of Psychology, University of California, Davis, United States; California National Primate Research Center, University of California, Davis, United States
| | - Alan J Conley
- Department of Population Health and Reproduction, University of California, Davis, United States
| | - Rebecca Cotterman
- Department of Population Health and Reproduction, University of California, Davis, United States
| | - Madison Dufek
- California National Primate Research Center, University of California, Davis, United States
| | - Leana R Goetze
- California National Primate Research Center, University of California, Davis, United States
| | - Allison R Lau
- California National Primate Research Center, University of California, Davis, United States; Graduate Program in Animal Behavior, University of California, Davis, United States
| | - Sally P Mendoza
- Department of Psychology, University of California, Davis, United States; California National Primate Research Center, University of California, Davis, United States
| | - Logan E Savidge
- Department of Psychology, University of California, Davis, United States; California National Primate Research Center, University of California, Davis, United States
| | - Karen L Bales
- Department of Psychology, University of California, Davis, United States; California National Primate Research Center, University of California, Davis, United States; Department of Neurobiology, Physiology, and Behavior, University of California, Davis, United States; Graduate Program in Animal Behavior, University of California, Davis, United States.
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Goymann W, Schwabl H. The tyranny of phylogeny-A plea for a less dogmatic stance on two-species comparisons: Funding bodies, journals and referees discourage two- or few-species comparisons, but such studies provide essential insights complementary to phylogenetic comparative studies. Bioessays 2021; 43:e2100071. [PMID: 34155665 DOI: 10.1002/bies.202100071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/04/2021] [Accepted: 06/08/2021] [Indexed: 11/11/2022]
Abstract
Phylogenetically controlled studies across multiple species correct for taxonomic confounds in physiological performance traits. Therefore, they are preferred over comparisons of two or few closely-related species. Funding bodies, referees and journal editors nowadays often even reject to consider detailed comparisons of two or few closely related species. Here, we plea for a less dogmatic stance on such comparisons, because phylogenetic studies come with their own limitations similar in magnitude as those of two-species comparisons. Two-species comparisons are particularly relevant and instructive for understanding physiological pathways and de novo mutations in three contexts: in a purely mechanistic context, when differences in the regulation of a trait are the focus of investigation, when a physiological trait lacks a direct connection to fitness, and when physiological measures cannot easily be standardized among laboratories. In conclusion, phylogenetic comparative and two-species studies have different strengths and weaknesses and combining these complementary approaches will help integrating biology.
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Affiliation(s)
- Wolfgang Goymann
- Department of Behavioural Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Hubert Schwabl
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
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Veitch JSM, Bowman J, Mastromonaco G, Schulte-Hostedde AI. Corticosterone response by Peromyscus mice to parasites, reproductive season, and age. Gen Comp Endocrinol 2021; 300:113640. [PMID: 33017585 DOI: 10.1016/j.ygcen.2020.113640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/14/2020] [Accepted: 09/28/2020] [Indexed: 01/15/2023]
Abstract
A common response to parasite infestations is increased production of glucocorticoid hormones that regulate immune function. We examined relationships between ectoparasite infestations and fecal corticosterone metabolites (FCM) in deer mice (Peromyscus maniculatus). Furthermore, we experimentally removed fleas to determine if reductions in ectoparasites affected FCM production. Individuals were assigned to control (no flea removal) or treatment (anti-flea application, physical combing) groups and individuals were recaptured to assess changes in FCM concentrations. There was a significant and negative effect of number of anti-flea treatment applications on FCM concentrations of deer mice. However, models including host biology traits and environmental predictors had a better model fit compared to models containing ectoparasite predictors. In particular, there was a significant relationship of deer mouse FCM with date and host age, where glucocorticoid production decreased towards the end of the breeding season and increased with age. Overall, adverse events associated with reproduction and age class, rather than ectoparasites, may be more important to variation in glucocorticoids of deer mice.
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Affiliation(s)
- Jasmine S M Veitch
- Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada. https://www.0000-0003-0010-3475
| | - Jeff Bowman
- Ontario Ministry of Natural Resources and Forestry, Wildlife Research and Monitoring Section, 2140 East Bank Drive, DNA Building, Peterborough, ON K9L 0G2, Canada; Trent University, 1600 East Bank Drive, Peterborough, ON K9L 0G2, Canada
| | - Gabriela Mastromonaco
- Reproductive Sciences, Toronto Zoo, 361A Old Finch Avenue, Toronto, ON M1B 5K7, Canada
| | - Albrecht I Schulte-Hostedde
- Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada. https://www.0000-0001-7263-4764
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Lattin CR, Kelly TR. Glucocorticoid negative feedback as a potential mediator of trade-offs between reproduction and survival. Gen Comp Endocrinol 2020; 286:113301. [PMID: 31622605 DOI: 10.1016/j.ygcen.2019.113301] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 02/01/2023]
Abstract
A large increase in glucocorticoid hormones can inhibit or completely shut down breeding in wild animals. Because of its critical role in reducing glucocorticoids after exposure to stressors, hypothalamic-pituitary-adrenal (HPA) negative feedback could be an important mediator of the ecological trade-off between investing limited resources into survival/self vs. reproduction/offspring. Although assessing negative feedback in a standardized way using injections of the synthetic glucocorticoid dexamethasone is a straightforward procedure, we show that several different approaches are used to report negative feedback in the literature, and then demonstrate that this can in turn affect the statistical results and conclusions of a study. We then review six specific predictions about adaptive within- and across-species patterns in glucocorticoids based on the relative costs and benefits of maintaining or abandoning breeding attempts when animals are faced with prolonged strong stressors, and examine evidence for these predictions in the context of HPA negative feedback. Thus far, evidence supporting these predictions for negative feedback is mixed, with the strongest evidence supporting a link between poor body condition and weak negative feedback in breeding animals. However, more research is necessary to assess the importance of changes in HPA negative feedback, especially in reptile, fish, and amphibian species. Furthermore, future research would benefit from reporting negative feedback ability in a standardized way, or at least making raw data available for the computation of alternate measures, to more easily compare studies in this growing area of research.
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Affiliation(s)
- Christine R Lattin
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Tosha R Kelly
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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Hair cortisol concentration in Siberian flying squirrels is unrelated to landscape and social factors. Naturwissenschaften 2019; 106:29. [DOI: 10.1007/s00114-019-1624-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 05/06/2019] [Accepted: 05/11/2019] [Indexed: 12/13/2022]
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Alderman S. Why cortisol soars in flying squirrels. J Exp Biol 2018. [DOI: 10.1242/jeb.170225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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