1
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Alward BA, Balthazart J, Ball GF. Androgen signaling in LMAN regulates song stereotypy in male canaries. Horm Behav 2024; 165:105611. [PMID: 39089160 DOI: 10.1016/j.yhbeh.2024.105611] [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: 01/29/2024] [Revised: 06/15/2024] [Accepted: 07/22/2024] [Indexed: 08/03/2024]
Abstract
During breeding when testosterone concentrations are high, male songbirds that are open-ended vocal learners like canaries (Serinus canaria) tend to produce a stable, stereotyped song that facilitates mate attraction or territory defense. Outside breeding contexts, song becomes more variable. The neuroendocrine mechanisms controlling this vocal variability across seasons are not entirely clear. We tested whether androgen signaling within the lateral magnocellular nucleus of the anterior nidopallium (LMAN), a cortical-like brain region of the vocal control system known as a vocal variability generator, plays a role in seasonal vocal variability. We first characterized song in birds housed alone on a short day (SD) photoperiod, which simulates non-breeding conditions. Then, cannulae filled with the androgen receptor (AR) blocker flutamide or left empty as control were implanted bilaterally in LMAN. Birds were then transferred to long days (LD) to simulate the breeding season and song was analyzed again. Blocking AR in LMAN increased acoustic variability of song and the acoustic variability of syllables. However, blocking AR in LMAN did not impact the variability of syllable usage nor their sequencing in LD birds, song features that are controlled by androgen signaling in a somatosensory brain region of the vocal control system called HVC. These findings highlight the multifactorial, non-redundant actions of steroid hormones in controlling complex social behaviors such as birdsong. They also support the hypothesis that LMAN is a key brain area for the effects of testosterone on song plasticity both seasonally in adults and during the song crystallization process at sexual maturity.
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Affiliation(s)
- Beau A Alward
- Department of Psychology, T.I.M.E.S, University of Houston, Houston, TX 77204, USA; Department of Biology and Biochemistry, University of Houston, Houston, TX 77004, USA; Department of Psychology, Neural and Cognitive Science Program, University of Maryland, College Park, MD 20742, USA
| | | | - Gregory F Ball
- Department of Psychology, Neural and Cognitive Science Program, University of Maryland, College Park, MD 20742, USA
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2
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Hurley LL, Ton R, Rowe M, Buchanan KL, Griffith SC, Crino OL. Longitudinal covariation of testosterone and sperm quality across reproductive stages in the zebra finch. Horm Behav 2023; 153:105388. [PMID: 37276837 DOI: 10.1016/j.yhbeh.2023.105388] [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: 10/04/2022] [Revised: 04/05/2023] [Accepted: 05/26/2023] [Indexed: 06/07/2023]
Abstract
Birds that breed opportunistically maintain partial activation of reproductive systems to rapidly exploit environmental conditions when they become suitable for breeding. Maintaining reproductive systems outside of a breeding context is costly. For males, these costs are thought to include continual exposure to testosterone. Males of seasonally breeding birds minimise these costs by downregulating testosterone production outside of a breeding context. Opportunistically breeding birds trade off the need to rapidly initiate reproduction with the costs of elevated testosterone production. One way opportunistically breeding males could minimise these costs is through fine scale changes in testosterone production across discrete reproductive stages which have a greater or lesser requirement for active sperm production. Although spermatogenesis broadly depends on testosterone production, whether changes in testosterone levels across the reproductive stages affect sperm quality and production is unknown. Here, we measured testosterone, sperm quality, and body condition in male zebra finches at discrete stages within reproductive bouts (egg laying, incubation, nestling provisioning, and fledging) and across two consecutive reproductive events in captive male zebra finches (Taeniopygia castanotis). We also examined associations between male testosterone, sperm quality/production, body condition, and nestling body condition. We found that testosterone levels varied across discrete reproductive stages with the lowest levels during incubation and the highest following chick fledging. Testosterone levels were positively associated with sperm velocity and the proportion of motile sperm but were not associated with male body condition. We found no associations between paternal body condition, testosterone levels, or sperm traits with nestling body condition (a proxy for the reproductive quality of a male and his partner). This study is the first to show that opportunistically breeding males vary testosterone synthesis and sperm traits at discrete stages within a reproductive event.
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Affiliation(s)
- Laura L Hurley
- School of Natural Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Riccardo Ton
- School of Natural Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Melissah Rowe
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), 6700 AB Wageningen, the Netherlands
| | - Katherine L Buchanan
- School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3216, Australia
| | - Simon C Griffith
- School of Natural Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Ondi L Crino
- School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3216, Australia; Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia; College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia.
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3
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Heidinger BJ, Slowinski SP, Sirman AE, Kittilson J, Gerlach NM, Ketterson ED. Experimentally elevated testosterone shortens telomeres across years in a free-living songbird. Mol Ecol 2022; 31:6216-6223. [PMID: 33503312 DOI: 10.1111/mec.15819] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 12/29/2020] [Accepted: 01/19/2021] [Indexed: 01/31/2023]
Abstract
Reproductive investment often comes at a cost to longevity, but the mechanisms that underlie these long-term effects are not well understood. In male vertebrates, elevated testosterone has been shown to increase reproductive success, but simultaneously to decrease survival. One factor that may contribute to or serve as a biomarker of these long-term effects of testosterone on longevity is telomeres, which are often positively related to lifespan and have been shown to shorten in response to reproduction. In this longitudinal study, we measured the effects of experimentally elevated testosterone on telomere shortening in free-living, male dark-eyed juncos (Junco hyemalis carolinensis), a system in which the experimental elevation of testosterone has previously been shown to increase reproductive success and reduce survival. We found a small, significant effect of testosterone treatment on telomeres, with testosterone-treated males exhibiting significantly greater telomere shortening with age than controls. These results are consistent with the hypothesis that increased telomere shortening may be a long-term cost of elevated testosterone exposure. As both testosterone and telomeres are conserved physiological mechanisms, our results suggest that their interaction may apply broadly to the long-term costs of reproduction in male vertebrates.
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Affiliation(s)
- Britt J Heidinger
- Biological Sciences Department, North Dakota State University, Fargo, ND, USA
| | | | - Aubrey E Sirman
- Biological Sciences Department, North Dakota State University, Fargo, ND, USA
| | - Jeffrey Kittilson
- Biological Sciences Department, North Dakota State University, Fargo, ND, USA
| | - Nicole M Gerlach
- Department of Biology, University of Florida, Gainesville, FL, USA
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4
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Rose EM, Haakenson CM, Ball GF. Sex differences in seasonal brain plasticity and the neuroendocrine regulation of vocal behavior in songbirds. Horm Behav 2022; 142:105160. [PMID: 35366412 DOI: 10.1016/j.yhbeh.2022.105160] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 11/20/2022]
Abstract
Birdsong is controlled in part by a discrete network of interconnected brain nuclei regulated in turn by steroid hormones and environmental stimuli. This complex interaction results in neural changes that occur seasonally as the environment varies (e.g., photoperiod, food/water availability, etc.). Variation in environment, vocal behavior, and neuroendocrine control has been primarily studied in male songbirds in both laboratory studies of captive birds and field studies of wild caught birds. The bias toward studying seasonality in the neuroendocrine regulation of song in male birds comes from a historic focus on sexually selected male behaviors. In fact, given that male song is often loud and accompanied by somewhat extravagant courtship behaviors, female song has long been overlooked. To compound this bias, the primary model songbird species for studies in the lab, zebra finches (Taeniopygia guttata) and canaries (Serinus canaria), exhibit little or no female song. Therefore, understanding the degree of variation and neuroendocrine control of seasonality in female songbirds is a major gap in our knowledge. In this review, we discuss the importance of studying sex differences in seasonal plasticity and the song control system. Specifically, we discuss sex differences in 1) the neuroanatomy of the song control system, 2) the distribution of receptors for androgens and estrogens and 3) the seasonal neuroplasticity of the hypothalamo-pituitary-gonadal axis as well as in the neural and cellular mechanisms mediating song system changes. We also discuss how these neuroendocrine mechanisms drive sex differences in seasonal behavior. Finally, we highlight specific gaps in our knowledge and suggest experiments critical for filling these gaps.
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Affiliation(s)
- Evangeline M Rose
- Department of Psychology, University of Maryland, College Park, MD, USA; Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA.
| | - Chelsea M Haakenson
- Department of Psychology, University of Maryland, College Park, MD, USA; Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA
| | - Gregory F Ball
- Department of Psychology, University of Maryland, College Park, MD, USA; Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA
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5
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Těšický M, Krajzingrová T, Eliáš J, Velová H, Svobodová J, Bauerová P, Albrecht T, Vinkler M. Inter-annual repeatability and age-dependent changes in plasma testosterone levels in a longitudinally monitored free-living passerine bird. Oecologia 2021; 198:53-66. [PMID: 34800165 DOI: 10.1007/s00442-021-05077-5] [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: 08/12/2020] [Accepted: 11/04/2021] [Indexed: 11/28/2022]
Abstract
While seasonal trends in testosterone levels are known from cross-cohort studies, data on testosterone inter-annual individual repeatability in wild birds are rare. Also, our understanding of hormonal age-dependent changes in testosterone levels is limited. We assessed plasma testosterone levels in 105 samples originating from 49 repeatedly captured free-living great tits (Parus major) sampled during the nesting to investigate their relative long-term repeatability and within-individual changes. Furthermore, we examined the inter-annual repeatability of condition-related traits (carotenoid- and melanin-based plumage ornamentation, ptilochronological feather growth rate, body mass, and haematological heterophil/lymphocyte ratio) and their relationships to testosterone levels. We show that testosterone levels are inter-annually repeatable in females, with a non-significant pattern in males, both in absolute values and individual ranks (indicating the maintenance of relative status in a population). In males, we found a quadratic dependence of testosterone levels on age, with a peak in midlife. In contrast, female testosterone levels showed no age-dependent trends. The inter-annual repeatability of condition-related traits ranged from zero to moderate and was mostly unrelated to plasma testosterone concentrations. However, males with elevated testosterone had significantly higher carotenoid-pigmented yellow plumage brightness, a trait presumably involved in mating. Showing inter-annual repeatability in testosterone levels, this research opens the way to further understanding the causes of variation in condition-related traits. Based on a longitudinal dataset, this study demonstrates that male plasma testosterone undergoes age-related changes that may regulate resource allocation. Our results thus suggest that, unlike females, male birds undergo hormonal senescence similar to mammals.
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Affiliation(s)
- Martin Těšický
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43, Prague, Czech Republic.
| | - Tereza Krajzingrová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43, Prague, Czech Republic
| | - Jiří Eliáš
- Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Kamýcká 129, 165 00, Prague, Czech Republic
| | - Hana Velová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43, Prague, Czech Republic
| | - Jana Svobodová
- Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Kamýcká 129, 165 00, Prague, Czech Republic
| | - Petra Bauerová
- Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Kamýcká 129, 165 00, Prague, Czech Republic.,Division of Air Quality, Czech Hydrometeorological Institute, Tušimice Observatory, Tušimice 6, 432 01, Kadaň, Czech Republic
| | - Tomáš Albrecht
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43, Prague, Czech Republic.,Institute of Vertebrate Biology, v.v.i., The Czech Academy of Sciences, Květná 8, 603 65, Brno, Czech Republic
| | - Michal Vinkler
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 128 43, Prague, Czech Republic
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6
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Wilson RC, Lutterschmidt DI. Energy Metrics of Red-Sided Garter Snakes ( Thamnophis sirtalis parietalis) Vary with Sex but Not Life-History Stage. Physiol Biochem Zool 2021; 93:347-357. [PMID: 32730193 DOI: 10.1086/709994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Because reproduction is energetically expensive, an organism's energy stores are likely involved in mediating transitions between reproductive and self-maintenance activities. We investigated whether body condition index, adipocyte follicle size, and liver glycogen differ with the life-history transition from reproduction to migration and foraging in red-sided garter snakes (Thamnophis sirtalis parietalis). Females primarily investing in mating behavior located at the den had a significantly higher body condition index than females migrating to summer feeding grounds. The body condition index of male snakes did not differ between snakes located at the den and those migrating to summer feeding grounds. Neither adipocyte follicle area nor liver glycogen stores differed significantly between snakes performing mating activities at the den and those migrating to summer feeding grounds. We did find a sexual dimorphism in that female red-sided garter snakes had significantly larger adipocyte follicles and higher liver glycogen compared with males. Our findings support the across-species phenomenon of females and males displaying a sexual dimorphism in stored energy substrates. Conversely, we did not find evidence to suggest that red-sided garter snakes primarily utilize fatty acids to fuel the initiation of migration, a finding that is not consistent with other long-distance migrators, such as birds. Because we did not find evidence to suggest that stored energy metrics influence the decision to migrate, a physiological mechanism that induces migration in red-sided garter snakes remains elusive.
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7
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Grant AR, Baldan D, Kimball MG, Malisch JL, Ouyang JQ. Across time and space: Hormonal variation across temporal and spatial scales in relation to nesting success. Gen Comp Endocrinol 2020; 292:113462. [PMID: 32171744 PMCID: PMC7187986 DOI: 10.1016/j.ygcen.2020.113462] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 02/16/2020] [Accepted: 03/10/2020] [Indexed: 12/30/2022]
Abstract
There is a renewed interest in investigating individual variation in hormone levels in relation to fitness metrics, as hormones act as mediators of life-history trade-offs. Hormone concentrations, however, are labile, responding to both internal and external stimuli, so the relationship between hormones and fitness can be non-consistent. One explanation of this inconsistent relationship is that a single hormone sample may not be representative of individual phenotypes in a free-living species. We addressed this issue by repeatedly sampling a free-living population of mountain white-crowned sparrows, Zonotrichia leucophrys oriantha, for baseline and stress-induced corticosterone (cort) and testosterone (T) across different stages of the breeding season. We measured (co)variation using three different methods, taking into account inter- and intra-individual variances, to determine whether hormone levels and the stress response are repeatable. We documented the temporal (over 3 months) and spatial (home-range) variation of individual hormone phenotypes and investigated how these components related to nesting success. At the population level, we found significant repeatability in male stress-induced cort concentrations but no repeatability in male or female baseline cort or male T concentrations. Using a new metric of intra-individual variance focusing on the stress response (profile repeatability), we found a wide range of variance scores, with most individuals showing high variation in their stress response. Similarly, we found a low level of repeatability of the reaction norm intercept and slope for the stress response across different life-history stages. Males with higher concentrations of stress-induced cort had more central home-ranges. Males with higher body condition had larger home-ranges; however, home-range size did not relate to male hormone concentrations or nesting success. We also did not find any significant relationship between variation in hormone levels and nesting success. We recommend that future studies combine both physiological and environmental components to better understand the relationship between hormones and fitness.
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Affiliation(s)
- Avery R Grant
- Department of Biology, University of Nevada, Reno, Reno, NV, USA.
| | - Davide Baldan
- Department of Biology, University of Nevada, Reno, Reno, NV, USA
| | - Melanie G Kimball
- Department of Biology, St. Mary's College of Maryland, St. Marys City, MD, USA
| | - Jessica L Malisch
- Department of Biology, St. Mary's College of Maryland, St. Marys City, MD, USA
| | - Jenny Q Ouyang
- Department of Biology, University of Nevada, Reno, Reno, NV, USA
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8
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Öst M, Noreikiene K, Angelier F, Jaatinen K. Sex-specific effects of the in ovo environment on early-life phenotypes in eiders. Oecologia 2019; 192:43-54. [PMID: 31786666 PMCID: PMC6974505 DOI: 10.1007/s00442-019-04569-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 11/25/2019] [Indexed: 12/14/2022]
Abstract
Maternal effects affect offspring phenotype and fitness. However, the roles of offspring sex-specific sensitivity to maternal glucocorticoids and sex-biased maternal investment remain unclear. It is also uncertain whether telomere length (a marker associated with lifespan) depends on early growth in a sex-specific manner. We assessed whether maternal traits including corticosterone (CORT; the main avian glucocorticoid) and in ovo growth rate are sex-specifically related to offspring CORT exposure, relative telomere length (RTL) and body condition in eiders (Somateria mollissima). We measured feather CORT (fCORT), RTL and body condition of newly hatched ducklings, and growth rate in ovo was expressed as tarsus length at hatching per incubation duration. Maternal traits included baseline plasma CORT, RTL, body condition and breeding experience. We found that fCORT was negatively associated with growth rate in daughters, while it showed a positive association in sons. Lower offspring fCORT was associated with higher maternal baseline plasma CORT, and fCORT was higher in larger clutches and in those hatching later. The RTL of daughters was negatively associated with maternal RTL, whereas that of males was nearly independent of maternal RTL. Higher fCORT in ovo was associated with longer RTL at hatching in both sexes. Duckling body condition was mainly explained by egg weight, and sons had a slightly lower body condition. Our correlational results suggest that maternal effects may have heterogeneous and even diametrically opposed effects between the sexes during early development. Our findings also challenge the view that prenatal CORT exposure is invariably associated with shorter telomeres.
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Affiliation(s)
- Markus Öst
- Environmental and Marine Biology, Åbo Akademi University, Turku, Finland. .,Novia University of Applied Sciences, Ekenäs, Finland.
| | - Kristina Noreikiene
- Chair of Aquaculture, Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi tn. 46, Tartu, Estonia
| | - Frederic Angelier
- Centre d'Etudes Biologiques de Chizé, CNRS, La Rochelle Université, UMR 7372, Villiers en Bois, France
| | - Kim Jaatinen
- Nature and Game Management Trust Finland, Degerby, Finland
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9
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Zychlinsky Scharff A, Rousseau M, Lacerda Mariano L, Canton T, Consiglio CR, Albert ML, Fontes M, Duffy D, Ingersoll MA. Sex differences in IL-17 contribute to chronicity in male versus female urinary tract infection. JCI Insight 2019; 5:122998. [PMID: 31145099 DOI: 10.1172/jci.insight.122998] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Sex-based differences influence incidence and outcome of infectious disease. Women have a significantly greater incidence of urinary tract infection (UTI) than men, yet, conversely, male UTI is more persistent with greater associated morbidity. Mechanisms underlying these sex-based differences are unknown, in part due to a lack of experimental models. We optimized a model to transurethrally infect male mice and directly compared UTI in both sexes. Although both sexes were initially equally colonized by uropathogenic E. coli, only male and testosterone-treated female mice remained chronically infected for up to 4 weeks. Female mice had more robust innate responses, including higher IL-17 expression, and increased γδ T cells and group 3 innate lymphoid cells in the bladder following infection. Accordingly, neutralizing IL-17 abolished resolution in female mice, identifying a cytokine pathway necessary for bacterial clearance. Our findings support the concept that sex-based responses to UTI contribute to impaired innate immunity in males and provide a rationale for non-antibiotic-based immune targeting to improve the response to UTI.
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Affiliation(s)
| | - Matthieu Rousseau
- Department of Immunology, Institut Pasteur, Paris, France.,INSERM U1223, Paris, France
| | - Livia Lacerda Mariano
- Department of Immunology, Institut Pasteur, Paris, France.,INSERM U1223, Paris, France
| | - Tracy Canton
- Department of Immunology, Institut Pasteur, Paris, France.,INSERM U1223, Paris, France
| | | | - Matthew L Albert
- Department of Immunology, Institut Pasteur, Paris, France.,INSERM U1223, Paris, France
| | - Magnus Fontes
- International Group for Data Analysis, Institut Pasteur, Paris, France.,The Centre for Mathematical Sciences, Lund University, Lund, Sweden.,The Center for Genomic Medicine at Rigshospitalet and Persimune, Copenhagen, Denmark
| | - Darragh Duffy
- Department of Immunology, Institut Pasteur, Paris, France.,INSERM U1223, Paris, France
| | - Molly A Ingersoll
- Department of Immunology, Institut Pasteur, Paris, France.,INSERM U1223, Paris, France
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10
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Moore IT, Vernasco BJ, Escallón C, Small TW, Ryder TB, Horton BM. Tales of testosterone: Advancing our understanding of environmental endocrinology through studies of neotropical birds. Gen Comp Endocrinol 2019; 273:184-191. [PMID: 29990493 DOI: 10.1016/j.ygcen.2018.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/21/2018] [Accepted: 07/06/2018] [Indexed: 01/29/2023]
Abstract
Studies of birds have greatly advanced our understanding of how testosterone modulates complex phenotypes, specifically its role in mediating male reproductive and associated behaviors. Yet most of the foundational studies have been limited to northern latitude breeding species despite the fact that they represent only a small fraction of worldwide avian diversity. In contrast, phylogenetic, life-history, and mating system diversity all reach their apex in neotropical avifauna and yet these birds, along with more southern latitude species, remain very poorly understood from an endocrine perspective. Despite the relatively limited previous work on taxa breeding in Central and South America, empirical findings have had a disproportionately large impact on our understanding of testosterone's role in everything from geographic variation to behavioral roles and neuroplasticity. Here, we synthesize how studies of neotropical breeding avifauna have advanced our understanding of how testosterone's actions can and are associated with the broad patterns of phenotypic diversity that we see in birds. In addition, we outline how these studies can be used individually or in a comparative context to address fundamental questions about the environmental endocrinology of testosterone and to understand the diversity of roles that testosterone plays in mediating behavioral variation, reproductive strategies, and associated life-history trade-offs.
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Affiliation(s)
- I T Moore
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
| | - B J Vernasco
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - C Escallón
- Departamento de Ciencias Básicas, Universidad de la Salle, Cra 2 No. 10-70, Bogotá, Colombia
| | - T W Small
- Department of Biology, University of Memphis, Memphis, TN 38152, USA
| | - T B Ryder
- Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, PO Box 37012, MRC 5503, Washington DC 20013, USA
| | - B M Horton
- Department of Biology, Millersville University of Pennsylvania, Millersville, PA 17551, USA
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11
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Covino KM, Jawor JM, Morris SR, Moore FR. Sex-specific hypothalamic-pituitary-gonadal axis sensitivity in migrating songbirds. Horm Behav 2018; 97:112-120. [PMID: 29128250 DOI: 10.1016/j.yhbeh.2017.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 10/13/2017] [Accepted: 11/03/2017] [Indexed: 01/21/2023]
Abstract
In seasonally migratory species, the overlap between the migratory and breeding life history stages is a balance between the physiological and behavioral requirements of each stage. Previous studies investigating the degree to which songbirds prepare for breeding during spring migration have focused on either circulating hormone levels or direct measures of gonadal recrudescence. In this study, we evaluated the phenology of breeding preparation in a long-distance migratory songbird, the Swainson's Thrush (Catharus ustulatus), by assessing hypothalamic-pituitary-gonadal (HPG) axis sensitivity with gonadotropin-releasing hormone (GnRH) bioassays throughout the migratory period. During spring migration both males and females had a significant response to GnRH injections as reflected in elevated testosterone levels. The magnitude of response to GnRH injections, Rpotential, in females stayed consistent throughout spring migration; however, Rpotential in males increased as the migratory season progressed. It is clear that at least some degree of endocrinological breeding development occurs either before or during spring migration in both sexes, however the phenology appears to be sex specific. In males this breeding development continues at a relatively steady pace throughout the migratory period while in females, relatively little endocrine breeding development occurs during migration. These sex-specific differences in the phenology of the endocrine breeding development warrant future investigations for both male and female songbirds. Moreover, research focused on how physiological breeding development is balanced with the expression of migratory traits in long-distance songbird migrants is needed.
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Affiliation(s)
- Kristen M Covino
- Biology Department, Canisius College, 2001 Main St., Buffalo, NY 14208, USA; Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA; Shoals Marine Laboratory, 102 Chase Ocean Engineering Lab, 24 Colovos Rd, Durham, NH 03824, USA.
| | - Jodie M Jawor
- Biology Department, Canisius College, 2001 Main St., Buffalo, NY 14208, USA
| | - Sara R Morris
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA; Shoals Marine Laboratory, 102 Chase Ocean Engineering Lab, 24 Colovos Rd, Durham, NH 03824, USA
| | - Frank R Moore
- Biology Department, Canisius College, 2001 Main St., Buffalo, NY 14208, USA
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12
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Cain KE, Pryke SR. Testosterone production in response to exogenous gonadotropin releasing hormone (GnRH challenge) depends on social environment and color polymorphism. Gen Comp Endocrinol 2017; 244:77-85. [PMID: 26752245 DOI: 10.1016/j.ygcen.2015.12.029] [Citation(s) in RCA: 7] [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: 04/30/2015] [Revised: 12/29/2015] [Accepted: 12/31/2015] [Indexed: 10/22/2022]
Abstract
Testosterone is an important mediator of behavior, morphology and physiology. A cascade of signals regulates the amount of testosterone (T) circulating in the plasma; in response to stimulus the hypothalamus releases gonadotropin-releasing hormone (GnRH), which triggers secretion of gonadotropins from the pituitary, stimulating the synthesis and release of T from the gonads. Previous work has shown that changes to the social environment can alter circulating T-levels, which may have important fitness consequences, but it is currently unclear whether these changes are due to alterations in the signal from the brain, or changes in the ability of the pituitary and gonads to respond to this signal. Further, the strength and direction of response to a changing environment may differ according to life-history strategy. Species with genetically determined alternative strategies offer a pathway for examining these differences. Here we use a finch with a genetically determined polymorphism, the Gouldian finch (Erythrura gouldiae), to determine whether T-levels change in response to social environment. We also use injections of GnRH to determine whether these changes are due to alterations in the ability of the pituitary and gonads to respond to this signal. We found that social environment (presence of females) had a rapid effect on male circulating T-levels, and that this difference was reflected in responsiveness to GnRH. We observed no overall morph differences in T-levels, but we did observe morph differences in the pattern of T secretion across environments, and morph differences in the repeatability of T-levels across time and environment.
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Affiliation(s)
- Kristal E Cain
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
| | - Sarah R Pryke
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia
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Cain KE, Pryke SR. Testosterone production ability predicts breeding success and tracks breeding stage in male finches. J Evol Biol 2016; 30:430-436. [PMID: 27797442 DOI: 10.1111/jeb.13005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 11/29/2022]
Abstract
Testosterone (T) is an important mediator of reproductive behaviours and potential target for selection. However, there are few data relating natural variation in T to fitness estimates. Here, we used the GnRH challenge (an injection of gonadotropin-releasing hormone which stimulates maximal T release), to examine how individual differences in T relate to reproductive success and how T changes across date and breeding stage. We measured pre- and post-challenge T, in captive male Gouldian finches (Erythrura gouldiae), before and after introducing females, and across breeding stage. Post-challenge T before introducing females positively predicted breeding success. Post-challenge T levels were unrelated to date, but strongly related to stage; T production ability was strongly attenuated in incubating males. Prechallenge T levels related only to date. Our results suggest that T production ability is an important target for selection and that when males invest heavily in parental care they reduce their sensitivity to GnRH.
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Affiliation(s)
- K E Cain
- Research School of Biology, Australian National University, Canberra, ACT, Australia.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - S R Pryke
- Research School of Biology, Australian National University, Canberra, ACT, Australia
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Longpre KM, Guterl JN, Katz LS. Proximity to females alters circulating testosterone concentrations and body weight in male goats. Small Rumin Res 2016. [DOI: 10.1016/j.smallrumres.2016.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Heiken KH, Brusch GA, Gartland S, Escallón C, Moore IT, Taylor EN. Effects of long distance translocation on corticosterone and testosterone levels in male rattlesnakes. Gen Comp Endocrinol 2016; 237:27-33. [PMID: 27468956 DOI: 10.1016/j.ygcen.2016.07.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 06/03/2016] [Accepted: 07/24/2016] [Indexed: 11/18/2022]
Abstract
Translocation is an increasingly common conservation tool used to augment declining populations or to remove nuisance animals from areas of human conflict. Studies show that venomous snakes translocated long distances may wander and experience increased mortality. However, potential sub-lethal physiological effects on translocated snakes remain unknown. We conducted an experimental study on free-ranging rattlesnakes to test the hypothesis that long distance translocation is stressful. The glucocorticoid response to translocation was variable among snakes. There was some evidence that translocation may be stressful, as baseline corticosterone levels in most snakes rose following translocation, whereas levels remained consistent in control snakes. Interestingly, testosterone levels rose dramatically following translocation, possibly reflecting effects of interaction with new environmental cues and/or resident snakes, or effects of navigation in a new environment. Corticosterone and testosterone were positively correlated. Our study shows that long distance translocation can affect steroid hormone concentrations in rattlesnakes, a result that should be taken into consideration when managing nuisance snakes or repatriating animals to the wild.
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Affiliation(s)
- Kory H Heiken
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93401, USA.
| | - George A Brusch
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93401, USA.
| | - Sarah Gartland
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93401, USA
| | - Camilo Escallón
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Ignacio T Moore
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Emily N Taylor
- Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA 93401, USA.
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Experimental elevation of wildlife testosterone using silastic tube implants. Res Vet Sci 2016; 108:1-7. [PMID: 27663363 DOI: 10.1016/j.rvsc.2016.07.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 05/22/2016] [Accepted: 07/02/2016] [Indexed: 11/21/2022]
Abstract
Testosterone (T) is a key androgen that mediates vertebrate molecular, cellular, and behavioral processes. Its manipulation is therefore of interest to a vast number of researchers studying animal behavior and reproduction, among others. Here, the usage of silastic implants across wildlife species is reviewed, and a method to manipulate rock hyrax (Procavia capensis) testosterone levels using silastic implants is presented. Using a series of in-vitro and in-vivo experiments, the secretion patterns of silastic tubes and silastic glue were tested and were surprisingly found to be similar. In addition, we studied endogenous T levels in wild-captured rock hyraxes (Procavia capensis), and using T implants succeeded in elevating T to the maximal physiological concentrations recorded during the mating period. The number of implants that were inserted was the only predictor of T levels, and seven 20mm implants were found to be the optimal dose. Implants induced sexual behaviors in the non-reproductive period. The duration of time that the implants were in the hyrax was the only significant factor that influenced the amount of T left over in the implant once it was removed. All together we affirm that T implants may offer a versatile tool for wildlife behavioral research by elevating T levels in the non-breeding period to maximal breeding levels.
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Bears H, Smith J, Wingfield J. Adrenocortical sensitivity to stress in Dark-eyed Juncos(Junco hyemalis oregonus)breeding in low and high elevation habitat. ECOSCIENCE 2016. [DOI: 10.1080/11956860.2003.11682758] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Sorensen MC, Jenni-Eiermann S, Spottiswoode CN. Why Do Migratory Birds Sing on Their Tropical Wintering Grounds? Am Nat 2016; 187:E65-76. [PMID: 26913952 DOI: 10.1086/684681] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Many long-distance migratory birds sing extensively on their tropical African wintering grounds, but the function of this costly behavior remains unknown. In this study, we carry out a first empirical test of three competing hypotheses, combining a field study of great reed warblers (Acrocephalus arundinaceus) wintering in Africa with a comparative analysis across Palearctic-African migratory songbird species. We asked whether winter song (i) functions to defend nonbreeding territories, (ii) functions as practice to improve complex songs for subsequent breeding, or (iii) is a nonadaptive consequence of elevated testosterone carryover. We found support for neither the long-assumed territory-defense hypothesis (great reed warblers had widely overlapping home ranges and showed no conspecific aggression) nor the testosterone-carryover hypothesis (winter singing in great reed warblers was unrelated to plasma testosterone concentration). Instead, we found strongest support for the song-improvement hypothesis, since great reed warblers sang a mate attraction song type rather than a territorial song type in Africa, and species that sing most intensely in Africa were those in which sexual selection acts most strongly on song characteristics; they had more complex songs and were more likely to be sexually monochromatic. This study underlines how sexual selection can have far-reaching effects on animal ecology throughout the annual cycle.
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Heimovics SA, Prior NH, Ma C, Soma KK. Rapid Effects of an Aggressive Interaction on Dehydroepiandrosterone, Testosterone and Oestradiol Levels in the Male Song Sparrow Brain: a Seasonal Comparison. J Neuroendocrinol 2016; 28:12345. [PMID: 26648568 DOI: 10.1111/jne.12345] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 11/10/2015] [Accepted: 11/27/2015] [Indexed: 12/13/2022]
Abstract
Across vertebrates, aggression is robustly expressed during the breeding season when circulating testosterone is elevated, and testosterone activates aggression either directly or after aromatisation into 17β-oestradiol (E2 ) in the brain. In some species, such as the song sparrow, aggressive behaviour is also expressed at high levels during the nonbreeding season, when circulating testosterone is non-detectable. At this time, the androgen precursor dehydroepiandrosterone (DHEA) is metabolised within the brain into testosterone and/or E2 to promote aggression. In the present study, we used captive male song sparrows to test the hypothesis that an acute agonistic interaction during the nonbreeding season, but not during the breeding season, would alter steroid levels in the brain. Nonbreeding and breeding subjects were exposed to either a laboratory simulated territorial intrusion (L-STI) or an empty cage for only 5 min. Immediately afterwards, the brain was rapidly collected and flash frozen. The Palkovits punch technique was used to microdissect specific brain regions implicated in aggressive behaviour. Solid phase extraction followed by radioimmunoassay was used to quantify DHEA, testosterone and E2 in punches. Overall, levels of DHEA, testosterone and E2 were higher in brain tissue than in plasma. Local testosterone and E2 levels in the preoptic area, anterior hypothalamus and nucleus taeniae of the amygdala were significantly higher in the breeding season than the nonbreeding season and were not affected by the L-STI. Unexpectedly, subjects that were dominant in the L-STI had lower levels of DHEA in the anterior hypothalamus and medial striatum in both seasons and lower levels of DHEA in the nucleus taeniae of the amygdala in the breeding season only. Taken together, these data suggest that local levels of DHEA in the brain are very rapidly modulated by social interactions in a context and region-specific pattern.
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Affiliation(s)
- S A Heimovics
- Department of Biology, University of St. Thomas, St Paul, MN, USA
| | - N H Prior
- Department of Psychology, University of British Columbia, Vancouver, Canada
| | - C Ma
- Department of Psychology, University of British Columbia, Vancouver, Canada
| | - K K Soma
- Department of Psychology, University of British Columbia, Vancouver, Canada
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Husak JF. Measuring Selection on Physiology in the Wild and Manipulating Phenotypes (in Terrestrial Nonhuman Vertebrates). Compr Physiol 2015; 6:63-85. [PMID: 26756627 DOI: 10.1002/cphy.c140061] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
To understand why organisms function the way that they do, we must understand how evolution shapes physiology. This requires knowledge of how selection acts on physiological traits in nature. Selection studies in the wild allow us to determine how variation in physiology causes variation in fitness, revealing how evolution molds physiology over evolutionary time. Manipulating phenotypes experimentally in a selection study shifts the distribution of trait variation in a population to better explore potential constraints and the adaptive value of physiological traits. There is a large database of selection studies in the wild on a variety of traits, but very few of those are physiological traits. Nevertheless, data available so far suggest that physiological traits, including metabolic rate, thermal physiology, whole-organism performance, and hormone levels, are commonly subjected to directional selection in nature, with stabilizing and disruptive selection less common than predicted if physiological traits are optimized to an environment. Selection studies on manipulated phenotypes, including circulating testosterone and glucocorticoid levels, reinforce this notion, but reveal that trade-offs between survival and reproduction or correlational selection can constrain the evolution of physiology. More studies of selection on physiological traits in nature that quantify multiple traits are necessary to better determine the manner in which physiological traits evolve and whether different types of traits (dynamic performance vs. regulatory) evolve differently.
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Affiliation(s)
- Jerry F Husak
- Department of Biology, University of St. Thomas, St. Paul, Minnesota, USA
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Reedy AM, Cox CL, Chung AK, Evans WJ, Cox RM. Both sexes suffer increased parasitism and reduced energy storage as costs of reproduction in the brown anole,Anolis sagrei. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12685] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Aaron M. Reedy
- Department of Biology; University of Virginia; 485 McCormick Road PO Box 400328 Charlottesville VA 22904 USA
| | - Christian L. Cox
- Department of Biology; Georgia Southern University; P.O. Box 8042 Statesboro GA 30460 USA
| | - Albert K. Chung
- Department of Biology; University of Virginia; 485 McCormick Road PO Box 400328 Charlottesville VA 22904 USA
| | - William J. Evans
- Department of Biology; University of Virginia; 485 McCormick Road PO Box 400328 Charlottesville VA 22904 USA
| | - Robert M. Cox
- Department of Biology; University of Virginia; 485 McCormick Road PO Box 400328 Charlottesville VA 22904 USA
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22
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Pultorak JD, Fuxjager MJ, Kalcounis-Rueppell MC, Marler CA. Male fidelity expressed through rapid testosterone suppression of ultrasonic vocalizations to novel females in the monogamous California mouse. Horm Behav 2015; 70:47-56. [PMID: 25725427 DOI: 10.1016/j.yhbeh.2015.02.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 02/14/2015] [Accepted: 02/18/2015] [Indexed: 11/26/2022]
Abstract
The steroid hormone testosterone (T) is a well-known mediator of male sexual behavior in vertebrates. However, less is known about T's rapid effects on sexual behavior, particularly those involving ultrasonic vocalizations (USVs), a mode of communication that can influence mate acquisition in rodents. Using the monogamous California mouse, Peromyscus californicus, we tested whether T rapidly alters male USV production by giving T or saline injections to non-paired (sexually naïve) males and paired (paternally experienced and pair-bonded) males immediately prior to a brief exposure to an unrelated, novel female. Among non-paired males, no differences in the total number of USVs were observed; however, T increased the proportion of simple sweeps produced. Among paired males, T decreased the number of USVs produced, and this change was driven by a reduction in simple sweeps. These results suggest a differential rapid effect of T pulses between non-paired and paired males upon exposure to a novel female. Additionally, we observed a positive correlation in the production of USVs made between males and novel females, and this relationship was altered by T. Given the importance of USVs in sexual communication, our study supports an essential concept of monogamy in that mate fidelity is reinforced by decreased responsiveness to prospective mates outside of the pair bond. The central mechanism in pair bonded males that decreases their responsiveness to novel females appears to be one that T can trigger. This is among the first studies to demonstrate that T can inhibit sexually related behaviors and do so rapidly.
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Affiliation(s)
- Joshua D Pultorak
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Matthew J Fuxjager
- Department of Biology, Wake Forest University, Winston-Salem, NC 27106, USA
| | | | - Catherine A Marler
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Psychology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Fokidis HB, Adomat HH, Kharmate G, Hosseini-Beheshti E, Guns ES, Soma KK. Regulation of local steroidogenesis in the brain and in prostate cancer: lessons learned from interdisciplinary collaboration. Front Neuroendocrinol 2015; 36:108-29. [PMID: 25223867 DOI: 10.1016/j.yfrne.2014.08.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 08/28/2014] [Accepted: 08/28/2014] [Indexed: 11/16/2022]
Abstract
Sex steroids play critical roles in the regulation of the brain and many other organs. Traditionally, researchers have focused on sex steroid signaling that involves travel from the gonads via the circulation to intracellular receptors in target tissues. This classic concept has been challenged, however, by the growing number of cases in which steroids are synthesized locally and act locally within diverse tissues. For example, the brain and prostate carcinoma were previously considered targets of gonadal sex steroids, but under certain circumstances, these tissues can upregulate their steroidogenic potential, particularly when circulating sex steroid concentrations are low. We review some of the similarities and differences between local sex steroid synthesis in the brain and prostate cancer. We also share five lessons that we have learned during the course of our interdisciplinary collaboration, which brought together neuroendocrinologists and cancer biologists. These lessons have important implications for future research in both fields.
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Affiliation(s)
- H Bobby Fokidis
- Department of Biology, Rollins College, Winter Park, FL 37289, USA; Department of Psychology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Vancouver Prostate Centre, Vancouver, BC V6H 3Z6, Canada.
| | - Hans H Adomat
- Vancouver Prostate Centre, Vancouver, BC V6H 3Z6, Canada
| | | | | | - Emma S Guns
- Vancouver Prostate Centre, Vancouver, BC V6H 3Z6, Canada; Department of Urological Sciences, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
| | - Kiran K Soma
- Department of Psychology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Graduate Program in Neuroscience, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Brain Research Centre, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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Rosvall KA, Peterson MP. Behavioral effects of social challenges and genomic mechanisms of social priming: What's testosterone got to do with it? Curr Zool 2014; 60:791-803. [PMID: 27721823 DOI: 10.1093/czoolo/60.6.791] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Social challenges from rival conspecifics are common in the lives of animals, and changes in an animal's social environment can influence physiology and behavior in ways that appear to be adaptive in the face of continued social instability (i.e. social priming). Recently, it has become clear that testosterone, long thought to be the primary mediator of these effects, may not always change in response to social challenges, an observation that highlights gaps in our understanding of the proximate mechanisms by which animals respond to their social environment. Here, our goal is to address the degree to which testosterone mediates organismal responses to social cues. To this end, we review the behavioral and physiological consequences of social challenges, as well as their underlying hormonal and gene regulatory mechanisms. We also present a new case study from a wild songbird, the dark-eyed junco (Junco hyemalis), in which we find largely divergent genome-wide transcriptional changes induced by social challenges and testosterone, respectively, in muscle and liver tissue. Our review underscores the diversity of mechanisms that link the dynamic social environment with an organisms' genomic, hormonal, and behavioral state. This diversity among species, and even among tissues within an organism, reveals new insights into the pattern and process by which evolution may alter proximate mechanisms of social priming.
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Affiliation(s)
- Kimberly A Rosvall
- Indiana University, Department of Biology and Center for the Integrative Study of Animal Behavior
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25
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Ramenofsky M, Németh Z. Regulatory mechanisms for the development of the migratory phenotype: roles for photoperiod and the gonad. Horm Behav 2014; 66:148-58. [PMID: 24780144 DOI: 10.1016/j.yhbeh.2014.04.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 04/21/2014] [Accepted: 04/22/2014] [Indexed: 12/15/2022]
Abstract
This article is part of a Special Issue "Energy Balance". Male white-crowned sparrows, Zonotrichia leucophrys gambelii, were studied to investigate roles of natural day length and the testes in regulating development and expression of the vernal migration phenotype. Previous work suggested that a pulse of androgen during winter months followed by the vernal increase in photoperiod promotes fueling (fat deposition) to support long distance flight; however, other traits required for successful migration remain untested. To investigate these points, birds were captured on their wintering grounds and castrated prior to winter solstice following Mattocks (1976). A subset of the castrates received 8mm Silastic implants of testosterone (T-castrates) and others blank implants (Blank-castrates) for 16 days in February. Shams were surgical controls. Migratory traits measured were as follows: 24h locomotor activity, prenuptial molt, body mass, fat score, flight muscle profile, cloacal protuberance (CPL) and plasma androgens measured over 28 weeks divided into 3 experimental periods (pre-implant, implant, and post-implant). Under short day lengths, castration increased diurnal locomotor activity over Shams. Testosterone implants temporarily enhanced CPL, plasma androgens and flight muscle enlargement, but failed to induce migratory restlessness. Whereas all groups exhibited seasonal increases in mass, fat score and muscle profile, only Shams showed timely onset and completion of prenuptial molt and migratory restlessness. Thus, for castrated males exposed to naturally increasing day lengths, the organizational effects of a transient testosterone surge were not sufficient to actuate a timely spring molt and migratory behavior. A fully functional testis that can organize central processes is required for the entire expression of the spring migratory phenotype.
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Affiliation(s)
- Marilyn Ramenofsky
- University of California Davis, Department of Neurobiology Physiology and Behavior, Davis, CA 95616, USA.
| | - Zoltán Németh
- University of California Davis, Department of Neurobiology Physiology and Behavior, Davis, CA 95616, USA
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26
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Leary CJ, Knapp R. The stress of elaborate male traits: integrating glucocorticoids with androgen-based models of sexual selection. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2013.12.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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27
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Villavicencio CP, Apfelbeck B, Goymann W. Parental care, loss of paternity and circulating levels of testosterone and corticosterone in a socially monogamous song bird. Front Zool 2014; 11:11. [PMID: 24517241 PMCID: PMC3932846 DOI: 10.1186/1742-9994-11-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 02/09/2014] [Indexed: 11/29/2022] Open
Abstract
Introduction In biparental birds testosterone levels of males are typically high during the mating phase and decrease during the parental phase. Testosterone implants may enhance mating behaviors, increase the likelihood of males to engage in extra-pair mating behavior and may reduce paternal care. Thus, sex steroids such as testosterone influence reproductive behaviors. Little is known, however, as to whether the more subtle differences in physiological concentrations of testosterone that occur between individuals are related to differences in paternal care, extra-pair behavior, and genetic paternity between those males. Here, we investigate these relationships in the male black redstart (Phoenicurus ochruros), a socially monogamous songbird with a low breeding synchrony. We used nestling provisioning as a proxy for parental care behavior and genetic paternity loss as a proxy for the efficiency of mate-guarding. Results There was no relationship between nestling provisioning and paternity loss of males. Baseline and gonadotropin releasing hormone (GnRH)-induced levels of testosterone, but not baseline corticosterone, were significantly higher during the mating than during the provisioning phase. Males fed more often when temperatures decreased and fed less when they sang more, but we found no correlation between parental behavior and baseline or GnRH-induced testosterone, and baseline corticosterone – both measured during either the mating or the parental phase. However, males that experienced loss of paternity had lower levels of testosterone during the provisioning phase than males that did not lose paternity. Further, males that lost paternity also expressed higher baseline levels of corticosterone. Conclusions Physiological differences in testosterone or baseline corticosterone were not related to differences in parental care, suggesting that the variation of testosterone within a physiological range may not relate to the degree of paternal care in this species. However, the profile of both hormones may indicate quality traits that influence the likelihood of the respective male to lose paternity.
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Affiliation(s)
- Camila P Villavicencio
- Abteilung für Verhaltensneurobiologie, Max-Planck-Institut für Ornithologie, Eberhard-Gwinner-Str, 6a, D-82319 Seewiesen, Germany.
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28
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Schmidt KL, Macdougall-Shackleton EA, Soma KK, Macdougall-Shackleton SA. Developmental programming of the HPA and HPG axes by early-life stress in male and female song sparrows. Gen Comp Endocrinol 2014; 196:72-80. [PMID: 24291303 DOI: 10.1016/j.ygcen.2013.11.014] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 11/02/2013] [Accepted: 11/17/2013] [Indexed: 01/15/2023]
Abstract
Variation in early environmental conditions can have long-term effects on physiology and behavior, a process referred to as developmental programming. In particular, exposure to early-life stressors can have long-term effects on regulation of the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes. Although these effects have been well documented in mammals, less is known about how early-life stress affects regulation of these endocrine systems in non-mammalian species. In the current study, we determined the long-term effects of early-life food restriction or corticosterone (CORT) treatment on the HPA axis of song sparrows (Melospiza melodia), including the responses to restraint stress, dexamethasone challenge, and ACTH challenge. In addition, we assessed long-term effects on the HPG axis by measuring sex steroid levels (testosterone in males and 17β-estradiol in females) before and after a gonadotropin-releasing hormone (GnRH) challenge. Subjects treated with CORT during development had larger increases in CORT in response to ACTH challenge than food-restricted or control subjects. Neither treatment affected the responses of CORT to restraint or dexamethasone. CORT-treated males also had higher initial testosterone levels, but neither treatment affected testosterone levels post-GnRH. Lastly, although GnRH challenge failed to increase circulating estradiol levels in females, females exposed to food restriction or CORT treatment had lower estradiol levels than control females. These results show that exposure to stress can developmentally program the endocrine system of songbirds and illustrate the importance of considering developmental conditions when determining the factors responsible for inter-individual variation in endocrine regulation.
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Affiliation(s)
- Kim L Schmidt
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada.
| | - Elizabeth A Macdougall-Shackleton
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
| | - Kiran K Soma
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Scott A Macdougall-Shackleton
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada; Department of Psychology, University of Western Ontario, London, Ontario, Canada
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Elevated testosterone advances onset of migratory restlessness in a nearctic-neotropical landbird. Behav Ecol Sociobiol 2014. [DOI: 10.1007/s00265-013-1671-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Wilcoxen TE, Bridge ES, Boughton RK, Hahn TP, Schoech SJ. Physiology of reproductive senescence in Florida scrub-jays: results from a long-term study and GnRH challenge. Gen Comp Endocrinol 2013; 194:168-74. [PMID: 24096038 DOI: 10.1016/j.ygcen.2013.09.016] [Citation(s) in RCA: 5] [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: 05/25/2013] [Revised: 09/10/2013] [Accepted: 09/13/2013] [Indexed: 11/22/2022]
Abstract
In most vertebrates, production of reproductive hormones wanes with age, co-occurring with a decline in reproductive output. Measurement of these hormones can serve as a key marker of the onset of reproductive senescence. Longitudinal studies of physiological parameters in populations of free-living animals are relatively uncommon; however, we have monitored baseline concentrations of hormones for nine years in a population of Florida scrub-jays (Aphelocoma coerulescens). We hypothesized that concentrations of circulating reproductive hormones change with age, and predicted declines in reproductive hormones in the oldest jays. We found that baseline levels of luteinizing hormone (LH) and testosterone (T) were relatively low in both young and old male breeders and reach their highest levels in birds aged 4-7years. Conversely, we found no age-related patterns in baseline levels of LH or estradiol in female jays. In males we determined which component of the hypothalamo-pituitary-gonadal (HPG) axis is responsible for observed age-based differences, by challenging males of different ages with gonadotropin-releasing hormone (GnRH); thereby allowing assessment of pituitary and gonadal responsiveness by measuring plasma concentrations of luteinizing hormone and testosterone, respectively. The magnitude of increase in levels of both LH and T in response to GnRH challenge decreased with age in male breeders. Combined with the baseline levels, the results from the GnRH challenge suggest that younger birds have the capability to produce higher levels of reproductive hormone, whereas the old birds may be constrained by senescence in their ability to produce these hormones.
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Affiliation(s)
- Travis E Wilcoxen
- Department of Biological Sciences, University of Memphis, 3778 Walker Avenue, Memphis, TN 38111, USA; Biology Department, Millikin University, 1184 West Main Street, Decatur, IL 62522, USA.
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Peterson MP, Rosvall KA, Taylor CA, Lopez JA, Choi JH, Ziegenfus C, Tang H, Colbourne JK, Ketterson ED. Potential for sexual conflict assessed via testosterone-mediated transcriptional changes in liver and muscle of a songbird. ACTA ACUST UNITED AC 2013; 217:507-17. [PMID: 24198265 DOI: 10.1242/jeb.089813] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Males and females can be highly dimorphic in metabolism and physiology despite sharing nearly identical genomes, and both sexes respond phenotypically to elevated testosterone, a steroid hormone that alters gene expression. Only recently has it become possible to learn how a hormone such as testosterone affects global gene expression in non-model systems, and whether it affects the same genes in males and females. To investigate the transcriptional mechanisms by which testosterone exerts its metabolic and physiological effects on the periphery, we compared gene expression by sex and in response to experimentally elevated testosterone in a well-studied bird species, the dark-eyed junco (Junco hyemalis). We identified 291 genes in the liver and 658 in the pectoralis muscle that were differentially expressed between males and females. In addition, we identified 1727 genes that were differentially expressed between testosterone-treated and control individuals in at least one tissue and sex. Testosterone treatment altered the expression of only 128 genes in both males and females in the same tissue, and 847 genes were affected significantly differently by testosterone treatment in the two sexes. These substantial differences in transcriptional response to testosterone suggest that males and females may employ different pathways when responding to elevated testosterone, despite the fact that many phenotypic effects of experimentally elevated testosterone are similar in both sexes. In contrast, of the 121 genes that were affected by testosterone treatment in both sexes, 78% were regulated in the same direction (e.g. either higher or lower in testosterone-treated than control individuals) in both males and females. Thus, it appears that testosterone acts through both unique and shared transcriptional pathways in males and females, suggesting multiple mechanisms by which sexual conflict can be mediated.
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Affiliation(s)
- Mark P Peterson
- Department of Biology, Center for Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
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Siefferman L, Liu M, Navara KJ, Mendonça MT, Hill GE. Effect of Prenatal and Natal Administration of Testosterone on Production of Structurally Based Plumage Coloration. Physiol Biochem Zool 2013; 86:323-32. [DOI: 10.1086/670383] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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33
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Natural variation in circulating testosterone does not predict nestling provisioning rates in the northern cardinal, Cardinalis cardinalis. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.02.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Testosterone affects neural gene expression differently in male and female juncos: a role for hormones in mediating sexual dimorphism and conflict. PLoS One 2013; 8:e61784. [PMID: 23613935 PMCID: PMC3627916 DOI: 10.1371/journal.pone.0061784] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 03/13/2013] [Indexed: 12/12/2022] Open
Abstract
Despite sharing much of their genomes, males and females are often highly dimorphic, reflecting at least in part the resolution of sexual conflict in response to sexually antagonistic selection. Sexual dimorphism arises owing to sex differences in gene expression, and steroid hormones are often invoked as a proximate cause of sexual dimorphism. Experimental elevation of androgens can modify behavior, physiology, and gene expression, but knowledge of the role of hormones remains incomplete, including how the sexes differ in gene expression in response to hormones. We addressed these questions in a bird species with a long history of behavioral endocrinological and ecological study, the dark-eyed junco (Junco hyemalis), using a custom microarray. Focusing on two brain regions involved in sexually dimorphic behavior and regulation of hormone secretion, we identified 651 genes that differed in expression by sex in medial amygdala and 611 in hypothalamus. Additionally, we treated individuals of each sex with testosterone implants and identified many genes that may be related to previously identified phenotypic effects of testosterone treatment. Some of these genes relate to previously identified effects of testosterone-treatment and suggest that the multiple effects of testosterone may be mediated by modifying the expression of a small number of genes. Notably, testosterone-treatment tended to alter expression of different genes in each sex: only 4 of the 527 genes identified as significant in one sex or the other were significantly differentially expressed in both sexes. Hormonally regulated gene expression is a key mechanism underlying sexual dimorphism, and our study identifies specific genes that may mediate some of these processes.
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Selman W, Jawor JM, Qualls CP. Seasonal Variation of Corticosterone Levels in Graptemys flavimaculata, an Imperiled Freshwater Turtle. COPEIA 2012. [DOI: 10.1643/cp-11-112] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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36
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Mccoy JC, Ditchkoff SS. Patterns of fecal hormones in a fenced population of white-tailed deer. WILDLIFE SOC B 2012. [DOI: 10.1002/wsb.190] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Meylan S, Miles DB, Clobert J. Hormonally mediated maternal effects, individual strategy and global change. Philos Trans R Soc Lond B Biol Sci 2012; 367:1647-64. [PMID: 22566673 DOI: 10.1098/rstb.2012.0020] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A challenge to ecologists and evolutionary biologists is predicting organismal responses to the anticipated changes to global ecosystems through climate change. Most evidence suggests that short-term global change may involve increasing occurrences of extreme events, therefore the immediate response of individuals will be determined by physiological capacities and life-history adaptations to cope with extreme environmental conditions. Here, we consider the role of hormones and maternal effects in determining the persistence of species in altered environments. Hormones, specifically steroids, are critical for patterning the behaviour and morphology of parents and their offspring. Hence, steroids have a pervasive influence on multiple aspects of the offspring phenotype over its lifespan. Stress hormones, e.g. glucocorticoids, modulate and perturb phenotypes both early in development and later into adulthood. Females exposed to abiotic stressors during reproduction may alter the phenotypes by manipulation of hormones to the embryos. Thus, hormone-mediated maternal effects, which generate phenotypic plasticity, may be one avenue for coping with global change. Variation in exposure to hormones during development influences both the propensity to disperse, which alters metapopulation dynamics, and population dynamics, by affecting either recruitment to the population or subsequent life-history characteristics of the offspring. We suggest that hormones may be an informative index to the potential for populations to adapt to changing environments.
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Affiliation(s)
- Sandrine Meylan
- Laboratoire Ecologie-Evolution, CNRS UMR 7625, Université Pierre et Marie Curie-Paris 6, 7 quai Saint Bernard, 75252 Paris cedex 05, France
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Rosvall KA, Reichard DG, Ferguson SM, Whittaker DJ, Ketterson ED. Robust behavioral effects of song playback in the absence of testosterone or corticosterone release. Horm Behav 2012; 62:418-25. [PMID: 22850247 PMCID: PMC3477244 DOI: 10.1016/j.yhbeh.2012.07.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 07/13/2012] [Accepted: 07/22/2012] [Indexed: 01/26/2023]
Abstract
Some species of songbirds elevate testosterone in response to territorial intrusions while others do not. The search for a general explanation for this interspecific variation in hormonal response to social challenges has been impeded by methodological differences among studies. We asked whether song playback alone is sufficient to bring about elevation in testosterone or corticosterone in the dark-eyed junco (Junco hyemalis), a species that has previously demonstrated significant testosterone elevation in response to a simulated territorial intrusion when song was accompanied by a live decoy. We studied two populations of juncos that differ in length of breeding season (6-8 vs. 14-16 weeks), and conducted playbacks of high amplitude, long-range song. In one population, we also played low amplitude, short-range song, a highly potent elicitor of aggression in juncos and many songbirds. We observed strong aggressive responses to both types of song, but no detectable elevation of plasma testosterone or corticosterone in either population. We also measured rise in corticosterone in response to handling post-playback, and found full capacity to elevate corticosterone but no effect of song class (long-range or short-range) on elevation. Collectively, our data suggest that males can mount an aggressive response to playback without a change in testosterone or corticosterone, despite the ability to alter these hormones during other types of social interactions. We discuss the observed decoupling of circulating hormones and aggression in relation to mechanisms of behavior and the cues that may activate the HPA and HPG axes.
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Peterson MP, Whittaker DJ, Ambreth S, Sureshchandra S, Buechlein A, Podicheti R, Choi JH, Lai Z, Mockatis K, Colbourne J, Tang H, Ketterson ED. De novo transcriptome sequencing in a songbird, the dark-eyed junco (Junco hyemalis): genomic tools for an ecological model system. BMC Genomics 2012; 13:305. [PMID: 22776250 PMCID: PMC3476391 DOI: 10.1186/1471-2164-13-305] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 07/09/2012] [Indexed: 11/25/2022] Open
Abstract
Background Though genomic-level data are becoming widely available, many of the metazoan species sequenced are laboratory systems whose natural history is not well documented. In contrast, the wide array of species with very well-characterized natural history have, until recently, lacked genomics tools. It is now possible to address significant evolutionary genomics questions by applying high-throughput sequencing to discover the majority of genes for ecologically tractable species, and by subsequently developing microarray platforms from which to investigate gene regulatory networks that function in natural systems. We used GS-FLX Titanium Sequencing (Roche/454-Sequencing) of two normalized libraries of pooled RNA samples to characterize a transcriptome of the dark-eyed junco (Junco hyemalis), a North American sparrow that is a classically studied species in the fields of photoperiodism, speciation, and hormone-mediated behavior. Results From a broad pool of RNA sampled from tissues throughout the body of a male and a female junco, we sequenced a total of 434 million nucleotides from 1.17 million reads that were assembled de novo into 31,379 putative transcripts representing 22,765 gene sets covering 35.8 million nucleotides with 12-fold average depth of coverage. Annotation of roughly half of the putative genes was accomplished using sequence similarity, and expression was confirmed for the majority with a preliminary microarray analysis. Of 716 core bilaterian genes, 646 (90 %) were recovered within our characterized gene set. Gene Ontology, orthoDB orthology groups, and KEGG Pathway annotation provide further functional information about the sequences, and 25,781 potential SNPs were identified. Conclusions The extensive sequence information returned by this effort adds to the growing store of genomic data on diverse species. The extent of coverage and annotation achieved and confirmation of expression, show that transcriptome sequencing provides useful information for ecological model systems that have historically lacked genomic tools. The junco-specific microarray developed here is allowing investigations of gene expression responses to environmental and hormonal manipulations – extending the historic work on natural history and hormone-mediated phenotypes in this system.
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Affiliation(s)
- Mark P Peterson
- Dept. of Biology, Center for Integrated Study of Animal Behavior, Indiana University, Bloomington, IN, USA.
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Scollon EJ, Carr JA, Rintoul DA, McMurry ST, Cobb GP. Metabolism and distribution of p,p'-DDT during flight of the white-crowned sparrow, Zonotrichia leucophrys. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2012; 31:336-346. [PMID: 22045600 DOI: 10.1002/etc.730] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 07/31/2011] [Accepted: 09/19/2011] [Indexed: 05/31/2023]
Abstract
This study evaluated the interactions of flight, fasting, and 1,1,1-trichloro-bis(4-chlorophenyl)ethane (p,p'-DDT) loading on residue metabolism and distribution in recently exposed white-crowned sparrows (Zonotrichia leucophrys). Female sparrows were dosed with 5 mg p,p'-DDT per kg body weight over 3 d. Following 1 d of recovery, sparrows were flown in a wind tunnel for up to 140 min, in 15-min blocks. Food was withheld from the start of the flight period until birds were euthanized. DDT, 1,1-dichloro-2,2-bis(4 chlorophenyl)ethane (DDD), and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE) were present in all tissues examined. 1-Chloro-2,2-bis(4-chlorophenyl)ethene (DDµ), 1,1-bis(4-chlorophenyl)ethane (p,p'-DDη), and 2,2-bis(4-chlorophenyl)ethanol (p,p'-DDOH) were not found. Fasting did not significantly affect the rate of residue increase over time in any of the tissues examined. When sparrows flew and fasted simultaneously, fasting seldom contributed to an increase in tissue residues. However, the length of time flown was significantly correlated with increasing toxicant concentrations in the brain, kidney, and liver, effectively demonstrating the potential for brief flights to enhance mobilization of DDT and its metabolites. Dose, flight, and fasting also increased residues in brain tissue. These contaminant redistributions may have important ramifications on the stresses experienced by migratory birds.
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Affiliation(s)
- Edward J Scollon
- Department of Environmental Toxicology, Texas Tech University, Lubbock, Texas, USA
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Carotenoid supplementation and GnRH challenges influence female endocrine physiology, immune function, and egg-yolk characteristics in Japanese quail (Coturnix japonica). J Comp Physiol B 2012; 182:687-702. [DOI: 10.1007/s00360-011-0638-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 11/02/2011] [Accepted: 12/21/2011] [Indexed: 10/14/2022]
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Role of testosterone in stimulating seasonal changes in a potential avian chemosignal. J Chem Ecol 2011; 37:1349-57. [PMID: 22173888 DOI: 10.1007/s10886-011-0050-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/21/2011] [Accepted: 12/08/2011] [Indexed: 10/14/2022]
Abstract
Songbird preen oil contains volatile and semivolatile compounds that may contain information about species, sex, individual identity, and season. We examined the relationship between testosterone (T) and the amounts of preen oil volatile and semivolatile compounds in wild and captive dark-eyed juncos (Junco hyemalis). In wild males and females, we observed an increase in volatile compound relative concentration early in the breeding season. This increase mirrored previously described seasonal elevation in T levels in wild males and females, suggesting a positive relationship between hormone levels and preen gland secretions, and a possible role for these secretions in signaling receptivity. In females, the greatest relative concentrations of most compounds were observed close to egg laying, a time when steroid hormones are high and also the only time that females respond to an injection of gonadotropin-releasing hormone with a short-term increase in T. In a study of captive juncos held on short days, we asked whether the seasonal increases observed in the wild could be induced with experimental elevation of T alone. We found that exogenous T stimulated the production of some volatile compounds in non-breeding individuals of both sexes. However, of the 15 compounds known to increase during the breeding season, only four showed an increase in relative concentration in birds that received T implants. Our results suggest that testosterone levels likely interact with other seasonally induced physiological changes to affect volatile compound amounts in preen oil.
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DeVries MS, Holbrook AL, Winters CP, Jawor JM. Non-breeding gonadal testosterone production of male and female northern cardinals (Cardinalis cardinalis) following GnRH challenge. Gen Comp Endocrinol 2011; 174:370-8. [PMID: 21986087 DOI: 10.1016/j.ygcen.2011.09.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2011] [Revised: 09/18/2011] [Accepted: 09/25/2011] [Indexed: 10/17/2022]
Abstract
Yearly, testosterone (T) levels fluctuate as many vertebrates cycle through reproductive and non-reproductive periods. Among many temperate birds, it is well established that levels of T peak as gonads recrudesce for breeding and then fall as gonads regress prior to the non-breeding season. While the tissues producing breeding season T are well studied, the tissues responsible for non-breeding T have received less investigative attention. We examined the ability of male and female Northern Cardinals (Cardinalis cardinalis) to elevate gonadal T following standardized injections of gonadotropin-releasing hormone (GnRH) across three non-breeding seasons. Males and females were capable of significantly elevating gonadal T production following GnRH injections during periods of reproductive quiescence. The magnitude of T elevation varied across the non-breeding season, but not between sexes. To our knowledge, this is the first report of a significant increase in gonadal T production following GnRH injections administered in the non-breeding season.
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Affiliation(s)
- M Susan DeVries
- Department of Biological Sciences, The University of Southern Mississippi, 118 College Drive # 5018, Hattiesburg, MS 39406, USA.
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Tonra CM, Marra PP, Holberton RL. Early elevation of testosterone advances migratory preparation in a songbird. ACTA ACUST UNITED AC 2011; 214:2761-7. [PMID: 21795574 DOI: 10.1242/jeb.054734] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The timing of events associated with spring migration can be an important determinant of fitness for migratory birds. The need to prepare and maintain physical condition for migration is one demand that must be met for early arrival on breeding areas, and this demand is compounded by the energetic demands of the physiological transition to breeding. Here, we examined whether migratory birds, specifically males, can adequately meet both of these demands by elevating the sex steroid testosterone early during migratory preparation. To test this, we used a captive experiment in which we photostimulated male dark-eyed juncos (Junco hyemalis) and manipulated circulating testosterone. We predicted males with elevated testosterone would prepare to migrate and breed faster than control males or males where the ability of testosterone to bind with receptors, or be converted to estradiol, was inhibited (testosterone inhibited). We measured migratory preparation using mass, food intake, fat deposits and nocturnal activity (Zugunruhe). To estimate breeding preparation, we measured the diameter of the cloacal protuberance (CP). We found that males in the testosterone treatment group began migratory preparation approximately 10 days before controls. There was no difference in the magnitude of peak migratory condition between testosterone-implanted birds and controls. Males implanted with testosterone also reached the onset of breeding preparation faster and had larger peak CP diameter compared with controls. Testosterone-inhibited birds showed no signs of migratory preparation and only a weak increase in CP diameter. These results demonstrate that early elevation of testosterone during migratory preparation could incur benefits for males in terms of the ability to depart earlier from non-breeding areas and arrive in a more advanced breeding condition. This experiment demonstrates that there may be important physiological underpinnings to known winter to breeding season carry-over effects in migratory birds.
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Affiliation(s)
- Christopher M Tonra
- Laboratory of Avian Biology, School of Biology and Ecology, University of Maine, Orono, ME 04469, USA.
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Marteinson SC, Kimmins S, Letcher RJ, Palace VP, Bird DM, Ritchie IJ, Fernie KJ. Diet exposure to technical hexabromocyclododecane (HBCD) affects testes and circulating testosterone and thyroxine levels in American kestrels (Falco sparverius). ENVIRONMENTAL RESEARCH 2011; 111:1116-1123. [PMID: 21917248 DOI: 10.1016/j.envres.2011.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 08/02/2011] [Accepted: 08/08/2011] [Indexed: 05/31/2023]
Abstract
Hexabromocyclododecane (HBCD) is a high-production-volume, brominated flame-retardant that is used in items such as polystyrene foams. HBCD has been detected in the environment, wildlife tissues and in humans globally with some of the highest recorded levels in predatory birds. This study examined the effects of exposure to environmentally relevant levels of HBCD on the reproductive physiology of captive male American kestrels (Falco sparverius), a predatory bird. Two sets of males were used: one group not housed with females (unpaired: nc=12, nHBCD=10) and the second group housed with females (breeding: nc=10, nHBCD=20). All treatment birds were exposed to 0.51 μg HBCD/g kestrel/day technical HBCD, and controls to safflower oil only, injected into their food during seasonal testicular development. Unpaired males were exposed for 3 weeks and euthanized for testicular analysis. Breeding males were exposed for 3 weeks prior to pairing and throughout the courtship period. The HBCD-exposed unpaired males had heavier testes (p≤0.017) and a trend towards more seminiferous tubules containing elongated spermatids (p=0.052). There was also a moderate increase in plasma testosterone concentrations (p=0.056) compared to controls. In breeding males, testosterone levels increased during courtship to culminate in higher levels than controls by the time the first egg was laid (p=0.010) and circulating free and total T4 was reduced throughout. The number of sperm cells reaching the perivitelline layer of the first egg for breeding males did not differ between the two groups. This study is the first report that HBCD exposure at environmentally relevant levels alters reproductive physiology in male birds and suggests that birds may be more sensitive to HBCD than mammals.
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Affiliation(s)
- Sarah C Marteinson
- Avian Science and Conservation Centre, McGill University, 21-111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec, Canada H9X 3V9
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Competitive females are successful females; phenotype, mechanism and selection in a common songbird. Behav Ecol Sociobiol 2011; 66:241-252. [PMID: 22345899 DOI: 10.1007/s00265-011-1272-5] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In a variety of taxa, male reproductive success is positively related to expression of costly traits such as large body size, ornaments, armaments, and aggression. These traits are thought to improve male competitive ability, and thus access to limited reproductive resources. Females of many species also express competitive traits. However, we know very little about the consequences of individual variation in competitive traits and the mechanisms that regulate their expression in females. Consequently, it is currently unclear whether females express competitive traits owing to direct selection or as an indirect result of selection on males. Here we examine females of a mildly dimorphic songbird (Junco hyemalis) to determine whether females, show positive covariance in traits (morphology and behavior) that may be important in a competition. We also examine whether trait expression relates either to testosterone (T) in terms of mechanism or to reproductive success in terms of function. We found that larger females were more aggressive and that greater ability to produce T in response to a physiological challenge consisting of a standardized injection of gonadotropin releasing hormone (GnRH) predicted some measures of female body size and aggression. Finally, we found that aggressive females had greater reproductive success. We conclude that testosterone may influence female phenotype and that females may benefit from expressing a competitive phenotype. We also suggest that the mild dimorphism observed in many species may be due in part to direct selection on females rather than simply a correlated response to selection in males.
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Ryan CP, Anderson WG, Gardiner LE, Hare JF. Stress-induced sex ratios in ground squirrels: support for a mechanistic hypothesis. Behav Ecol 2011. [DOI: 10.1093/beheco/arr169] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Marasco V, Fusani L, Dessì-Fulgheri F, Canoine V. Non-migratory stonechats show seasonal changes in the hormonal regulation of non-seasonal territorial aggression. Horm Behav 2011; 60:414-9. [PMID: 21803045 DOI: 10.1016/j.yhbeh.2011.07.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 07/13/2011] [Accepted: 07/14/2011] [Indexed: 11/29/2022]
Abstract
In many birds and mammals, male territorial aggression is modulated by elevated circulating concentrations of the steroid hormone testosterone (T) during the breeding season. However, many species are territorial also during the non-breeding season, when plasma T levels are basal. The endocrine control of non-breeding territorial aggression differs considerably between species, and previous studies on wintering birds suggest differences between migratory and resident species. We investigated the endocrine modulation of territorial aggression during the breeding and non-breeding season in a resident population of European stonechats (Saxicola torquata rubicola). We recorded the aggressive response to a simulated territorial intrusion in spring and winter. Then, we compared the territorial aggression between seasons and in an experiment in which we blocked the androgenic and estrogenic action of T. We found no difference in the aggressive response between the breeding and the non-breeding season. However, similarly to what is found in migratory stonechats, the hormonal treatment decreased aggressive behaviors in resident males in the breeding season, whereas no effects were recorded in the non-breeding season. When we compared the aggressive responses of untreated birds with those obtained from migratory populations in a previous study, we found that territorial aggression of resident males was lower than that of migratory males during the breeding season. Our results show that in a resident population of stonechats T and/or its metabolites control territorial aggression in the breeding but not in the non-breeding season. In addition, our study supports the hypothesis that migratory status does modulate the intensity of aggressive behavior.
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Affiliation(s)
- Valeria Marasco
- Department of Evolutionary Biology Leo Pardi, University of Florence, Via Romana 17, 50125 Florence, Italy
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Klukowski M. Effects of breeding season, testosterone and ACTH on the corticosterone response of free-ranging male fence lizards (Sceloporus undulatus). Gen Comp Endocrinol 2011; 173:295-302. [PMID: 21703273 DOI: 10.1016/j.ygcen.2011.06.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 05/30/2011] [Accepted: 06/05/2011] [Indexed: 11/25/2022]
Abstract
An attenuated stress response during the breeding season has been reported for several vertebrate species, but the underlying physiological mechanism has received little attention, particularly in reptiles. Modulation could involve changes in the capacity of the adrenal gland to secrete glucocorticoids in addition to upstream changes in the pituitary or hypothalamus. In this study the magnitude of the corticosterone response to capture and confinement was compared between the breeding and postbreeding season in adult male eastern fence lizards, Sceloporus undulatus. Males were captured in both seasons and subjected to the identical stressor of 4h of confinement. Plasma corticosterone levels in response to confinement were significantly lower in the breeding than the postbreeding season. The effect of testosterone on the stress response was tested by experimentally elevating plasma testosterone levels via silastic implants in free-living males during the postbreeding season. Males with experimentally elevated testosterone exhibited significantly weaker corticosterone responses to 1h of confinement than sham-implanted males. Finally the capacity of the adrenal glands to secrete corticosterone during the breeding season was tested by challenging males with adrenocorticotropin (ACTH) injections. In spite of naturally suppressed corticosterone responses during the breeding season, males nonetheless responded robustly to ACTH. Altogether these results suggest that modulation resides upstream of the adrenal gland, as has been shown in some arctic-breeding avian species, and likely involves seasonal changes in testosterone levels.
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Affiliation(s)
- Matthew Klukowski
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132, USA.
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Cain KE, Rich MS, Ainsworth K, Ketterson ED. Two sides of the same coin? Consistency in aggression to conspecifics and predators in a female songbird. Ethology 2011; 117:786-795. [PMID: 21927524 DOI: 10.1111/j.1439-0310.2011.01932.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Different forms of aggression have traditionally been treated separately according to function or context (e.g. aggression towards a conspecific versus a predator). However, recent work on individual consistency in behavior predicts that different forms of aggression may be correlated across contexts, suggesting a lack of independence. For nesting birds, aggression towards both conspecifics and nest predators can affect reproductive success, yet the relationship between these behaviors, especially in females, is not known. Here we examine free-living female dark-eyed juncos (Junco hyemalis) and compare their aggressive responses towards three types of simulated intruders near the nest: a same-sex conspecific, an opposite-sex conspecific, and a nest predator. We also examine differences in the strength of response that might relate to the immediacy of the perceived threat the intruder poses for the female or her offspring. We found greater aggression directed towards a predator than a same-sex intruder, and towards a same-sex than an opposite-sex intruder, consistent with a predator being a more immediate threat than a same-sex intruder, followed by an opposite-sex intruder. We also found positive relationships across individuals between responses to a same-sex intruder and a simulated predator, and between responses to a same-sex and an opposite-sex intruder, indicating that individual females are consistent in their relative level of aggression across contexts. If correlated behaviors are mediated by related mechanisms, then different forms of aggression may be expressions of the same behavioral tendency and constrained from evolving independently.
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Affiliation(s)
- K E Cain
- Department of Biology & Center for the Integrative Study of Animal Behavior, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405, USA
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