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Holtz MA, Racicot R, Preininger D, Stuckert AMM, Mangiamele LA. Genome assembly of the foot-flagging frog, Staurois parvus: a resource for understanding mechanisms of behavior. G3 (BETHESDA, MD.) 2023; 13:jkad193. [PMID: 37625789 PMCID: PMC10542557 DOI: 10.1093/g3journal/jkad193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 03/22/2023] [Accepted: 08/13/2023] [Indexed: 08/27/2023]
Abstract
Elaborate and skilled movements of the body have been selected in a variety of species as courtship and rivalry signals. One roadblock in studying these behaviors has been a lack of resources for understanding how they evolved at the genetic level. The Bornean rock frog (Staurois parvus) is an ideal species in which to address this issue. Males wave their hindlimbs in a "foot-flagging" display when competing for mates. The evolution of foot flagging in S. parvus and other species is accompanied by increases in the expression of the androgen receptor gene within its neuromuscular system, but it remains unclear what genetic or transcriptional changes are associated with this behavioral phenotype. We have now assembled the genome of S. parvus, resulting in 3.98 Gbp of 22,402 contigs with an N50 of 611,229 bp. The genome will be a resource for finding genes related to the physiology underlying foot flagging and to adaptations of the neuromuscular system. As a first application of the genome, we also began work in comparative genomics and differential gene expression analysis. We show that the androgen receptor is diverged from other anuran species, and we identify unique expression patterns of genes in the spinal cord and leg muscle that are important for axial patterning, cell specification and morphology, or muscle contraction. This genome will continue to be an important tool for future -omics studies to understand the evolution of elaborate signaling behaviors in this and potentially related species.
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Affiliation(s)
- Mika A Holtz
- Department of Biological Sciences, Smith College, Northampton, MA 01053, USA
| | - Riccardo Racicot
- Department of Biological Sciences, Smith College, Northampton, MA 01053, USA
| | - Doris Preininger
- Vienna Zoo, 1130 Vienna, Austria
- Department of Evolutionary Biology, University of Vienna, 1030 Vienna, Austria
| | - Adam M M Stuckert
- Department of Biology & Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Lisa A Mangiamele
- Department of Biological Sciences, Smith College, Northampton, MA 01053, USA
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2
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Anderson AP, Renn SCP. The Ancestral Modulation Hypothesis: Predicting Mechanistic Control of Sexually Heteromorphic Traits Using Evolutionary History. Am Nat 2023; 202:241-259. [PMID: 37606950 DOI: 10.1086/725438] [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: 08/23/2023]
Abstract
AbstractAcross the animal kingdom there are myriad forms within a sex across, and even within, species, rendering concepts of universal sex traits moot. The mechanisms that regulate the development of these trait differences are varied, although in vertebrates, common pathways involve gonadal steroid hormones. Gonadal steroids are often associated with heteromorphic trait development, where the steroid found at higher circulating levels is the one involved in trait development for that sex. Occasionally, there are situations in which a gonadal steroid associated with heteromorphic trait development in one sex is involved in heteromorphic or monomorphic trait development in another sex. We propose a verbal hypothesis, the ancestral modulation hypothesis (AMH), that uses the evolutionary history of the trait-particularly which sex ancestrally possessed higher trait values-to predict the regulatory pathway that governs trait expression. The AMH predicts that the genomic architecture appears first to resolve sexual conflict in an initially monomorphic trait. This architecture takes advantage of existing sex-biased signals, the gonadal steroid pathway, to generate trait heteromorphism. In cases where the other sex experiences evolutionary pressure for the new phenotype, that sex will co-opt the existing architecture by altering its signal to match that of the original high-trait-value sex. We describe the integrated levels needed to produce this pattern and what the expected outcomes will be given the evolutionary history of the trait. We present this framework as a testable hypothesis for the scientific community to investigate and to create further engagement and analysis of both ultimate and proximate approaches to sexual heteromorphism.
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3
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Zimmer C, Taff CC, Ardia DR, Rosvall KA, Kallenberg C, Bentz AB, Taylor AR, Johnson LS, Vitousek MN. Gene expression in the female tree swallow brain is associated with inter- and intra-population variation in glucocorticoid levels. Horm Behav 2023; 147:105280. [PMID: 36403365 DOI: 10.1016/j.yhbeh.2022.105280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 10/12/2022] [Accepted: 11/07/2022] [Indexed: 11/18/2022]
Abstract
Studies of the evolutionary causes and consequences of variation in circulating glucocorticoids (GCs) have begun to reveal how they are shaped by selection. Yet the extent to which variation in circulating hormones reflects variation in other important regulators of the hypothalamic-pituitary-adrenal (HPA) axis, and whether these relationships vary among populations inhabiting different environments, remain poorly studied. Here, we compare gene expression in the brain of female tree swallows (Tachycineta bicolor) from populations that breed in environments that differ in their unpredictability. We find evidence of inter-population variation in the expression of glucocorticoid and mineralocorticoid receptors in the hypothalamus, with the highest gene expression in a population from an extreme environment, and lower expression in a population from a more consistent environment as well as in birds breeding at an environmentally variable high-altitude site that are part of a population that inhabits a mixture of high and low altitude habitats. Within some populations, variation in circulating GCs predicted differences in gene expression, particularly in the hypothalamus. However, some patterns were present in all populations, whereas others were not. These results are consistent with the idea that some combination of local adaptation and phenotypic plasticity may modify components of the HPA axis affecting stress resilience. Our results also underscore that a comprehensive understanding of the function and evolution of the stress response cannot be gained from measuring circulating hormones alone, and that future studies that apply a more explicitly evolutionary approach to important regulatory traits are likely to provide significant insights.
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Affiliation(s)
- Cedric Zimmer
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA; Laboratoire d'Ethologie Expérimentale et Comparée, LEEC, Université Sorbonne Paris Nord, UR 4443, 93430 Villetaneuse, France.
| | - Conor C Taff
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA; Cornell Lab of Ornithology, Ithaca, NY 14850, USA
| | - Daniel R Ardia
- Department of Biology, Franklin and Marshall College, Lancaster, PA 17604, USA
| | - Kimberly A Rosvall
- Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA
| | - Christine Kallenberg
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Alexandra B Bentz
- Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA; Department of Biology, University of Oklahoma, Norman, OK 73019, USA
| | - Audrey R Taylor
- Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - L Scott Johnson
- Department of Biological Sciences, Towson University, Towson, MD 21252, USA
| | - Maren N Vitousek
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA; Cornell Lab of Ornithology, Ithaca, NY 14850, USA
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4
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Rosvall KA. Evolutionary endocrinology and the problem of Darwin's tangled bank. Horm Behav 2022; 146:105246. [PMID: 36029721 DOI: 10.1016/j.yhbeh.2022.105246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 06/20/2022] [Accepted: 08/10/2022] [Indexed: 11/04/2022]
Abstract
Like Darwin's tangled bank of biodiversity, the endocrine mechanisms that give rise to phenotypic diversity also exhibit nearly endless forms. This tangled bank of mechanistic diversity can prove problematic as we seek general principles on the role of endocrine mechanisms in phenotypic evolution. A key unresolved question is therefore: to what degree are specific endocrine mechanisms re-used to bring about replicated phenotypic evolution? Related areas of inquiry are booming in molecular ecology, but behavioral traits are underrepresented in this literature. Here, I leverage the rich comparative tradition in evolutionary endocrinology to evaluate whether and how certain mechanisms may be repeated hotspots of behavioral evolutionary change. At one extreme, mechanisms may be parallel, such that evolution repeatedly uses the same gene or pathway to arrive at multiple independent (or, convergent) origins of a particular behavioral trait. At the other extreme, the building blocks of behavior may be unique, such that outwardly similar phenotypes are generated via lineage-specific mechanisms. This review synthesizes existing case studies, phylogenetic analyses, and experimental evolutionary research on mechanistic parallelism in animal behavior. These examples show that the endocrine building blocks of behavior have some elements of parallelism across replicated evolutionary events. However, support for parallelism is variable among studies, at least some of which relates to the level of complexity at which we consider sameness (i.e. pathway vs. gene level). Moving forward, we need continued experimentation and better testing of neutral models to understand whether, how - and critically, why - mechanism A is used in one lineage and mechanism B is used in another. We also need continued growth of large-scale comparative analyses, especially those that can evaluate which endocrine parameters are more or less likely to undergo parallel evolution alongside specific behavioral traits. These efforts will ultimately deepen understanding of how and why hormone-mediated behaviors are constructed the way that they are.
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Affiliation(s)
- Kimberly A Rosvall
- Indiana University, Bloomington, USA; Department of Biology, USA; Center for the Integrative Study of Animal Behavior, USA.
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5
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Cox RM, Hale MD, Wittman TN, Robinson CD, Cox CL. Evolution of hormone-phenotype couplings and hormone-genome interactions. Horm Behav 2022; 144:105216. [PMID: 35777215 DOI: 10.1016/j.yhbeh.2022.105216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 06/05/2022] [Accepted: 06/20/2022] [Indexed: 12/22/2022]
Abstract
When selection favors a new relationship between a cue and a hormonally mediated response, adaptation can proceed by altering the hormonal signal that is produced or by altering the phenotypic response to the hormonal signal. The field of evolutionary endocrinology has made considerable progress toward understanding the evolution of hormonal signals, but we know much less about the evolution of hormone-phenotype couplings, particularly at the hormone-genome interface. We briefly review and classify the mechanisms through which these hormone-phenotype couplings likely evolve, using androgens and their receptors and genomic response elements to illustrate our view. We then present two empirical studies of hormone-phenotype couplings, one rooted in evolutionary quantitative genetics and another in comparative transcriptomics, each focused on the regulation of sexually dimorphic phenotypes by testosterone (T) in the brown anole lizard (Anolis sagrei). First, we illustrate the potential for hormone-phenotype couplings to evolve by showing that coloration of the dewlap (an ornament used in behavioral displays) exhibits significant heritability in its responsiveness to T, implying that anoles harbor genetic variance in the architecture of hormonal pleiotropy. Second, we combine T manipulations with analyses of the liver transcriptome to ask whether and how statistical methods for characterizing modules of co-expressed genes and in silico techniques for identifying androgen response elements (AREs) can improve our understanding of hormone-genome interactions. We conclude by emphasizing important avenues for future work at the hormone-genome interface, particularly those conducted in a comparative evolutionary framework.
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Affiliation(s)
- Robert M Cox
- Department of Biology, University of Virginia, Charlottesville, VA, USA.
| | - Matthew D Hale
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Tyler N Wittman
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | | | - Christian L Cox
- Department of Biology, University of Virginia, Charlottesville, VA, USA; Biological Sciences, Florida International University, Miami, FL, USA
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6
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Schwark RW, Fuxjager MJ, Schmidt MF. Proposing a neural framework for the evolution of elaborate courtship displays. eLife 2022; 11:e74860. [PMID: 35639093 PMCID: PMC9154748 DOI: 10.7554/elife.74860] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 05/06/2022] [Indexed: 11/15/2022] Open
Abstract
In many vertebrates, courtship occurs through the performance of elaborate behavioral displays that are as spectacular as they are complex. The question of how sexual selection acts upon these animals' neuromuscular systems to transform a repertoire of pre-existing movements into such remarkable (if not unusual) display routines has received relatively little research attention. This is a surprising gap in knowledge, given that unraveling this extraordinary process is central to understanding the evolution of behavioral diversity and its neural control. In many vertebrates, courtship displays often push the limits of neuromuscular performance, and often in a ritualized manner. These displays can range from songs that require rapid switching between two independently controlled 'voice boxes' to precisely choreographed acrobatics. Here, we propose a framework for thinking about how the brain might not only control these displays, but also shape their evolution. Our framework focuses specifically on a major midbrain area, which we view as a likely important node in the orchestration of the complex neural control of behavior used in the courtship process. This area is the periaqueductal grey (PAG), as studies suggest that it is both necessary and sufficient for the production of many instinctive survival behaviors, including courtship vocalizations. Thus, we speculate about why the PAG, as well as its key inputs, might serve as targets of sexual selection for display behavior. In doing so, we attempt to combine core ideas about the neural control of behavior with principles of display evolution. Our intent is to spur research in this area and bring together neurobiologists and behavioral ecologists to more fully understand the role that the brain might play in behavioral innovation and diversification.
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Affiliation(s)
- Ryan W Schwark
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
- Neuroscience Graduate Group, University of PennsylvaniaPhiladelphiaUnited States
| | - Matthew J Fuxjager
- Department of Ecology, Evolution, and Organismal Biology, Brown UniversityProvidenceUnited States
| | - Marc F Schmidt
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
- Neuroscience Graduate Group, University of PennsylvaniaPhiladelphiaUnited States
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7
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Schuppe ER, Tobiansky D, Goller F, Fuxjager MJ. Specialized androgen synthesis in skeletal muscles that actuate elaborate social displays. J Exp Biol 2022; 225:275472. [PMID: 35587151 DOI: 10.1242/jeb.243730] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 05/12/2022] [Indexed: 11/20/2022]
Abstract
Androgens mediate the expression of many reproductive behaviors, including the elaborate displays used to navigate courtship and territorial interactions. In some vertebrates, males can produce androgen-dependent sexual behavior even when levels of testosterone (T) is low in the bloodstream. One idea is that select tissues make their own androgens from scratch to support behavioral performance. We first study this phenomenon in the skeletal muscles that actuate elaborate sociosexual displays in downy woodpeckers and two songbirds. We show that the woodpecker display muscle maintains elevated T when the testes are regressed in the non-breeding season. Both the display muscles of woodpeckers, as well as the display muscles in the avian vocal organ (syrinx or SYR) of songbirds, express all transporters and enzymes necessary to convert cholesterol into bioactive androgens locally. In a final analysis, we broaden our study by looking for these same transporters and enzymes in mammalian muscles that operate at different speeds. Using RNA-seq data, we find that the capacity for de novo synthesis is only present in "superfast" extraocular muscle. Together, our results suggest that skeletal muscle specialized to generate extraordinary twitch-times and/or extremely rapid contractile speeds may depend on androgenic hormones produced locally within the muscle itself. Our study therefore uncovers an important new dimension of androgenic regulation of behavior.
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Affiliation(s)
- Eric R Schuppe
- Department of Neurobiology and Behavior, Cornell University, 215 Tower Road, Ithaca, NY 14850, USA
| | - Daniel Tobiansky
- Department of Ecology, Evolution, and Organismal Biology, Brown University, 171 Meeting Street, Providence, RI 02912, USA
| | - Franz Goller
- Department of Biology, University of Utah, USA.,Institute for Zoophysiology, University of Münster, Germany
| | - Matthew J Fuxjager
- Department of Ecology, Evolution, and Organismal Biology, Brown University, 171 Meeting Street, Providence, RI 02912, USA
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8
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Fuxjager MJ, Fusani L, Schlinger BA. Physiological innovation and the evolutionary elaboration of courtship behaviour. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2021.03.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Anderson NK, Schuppe ER, Gururaja KV, Mangiamele LA, Martinez JCC, Priti H, May RV, Preininger D, Fuxjager MJ. A Common Endocrine Signature Marks the Convergent Evolution of an Elaborate Dance Display in Frogs. Am Nat 2021; 198:522-539. [PMID: 34559606 DOI: 10.1086/716213] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractUnrelated species often evolve similar phenotypic solutions to the same environmental problem, a phenomenon known as convergent evolution. But how do these common traits arise? We address this question from a physiological perspective by assessing how convergence of an elaborate gestural display in frogs (foot-flagging) is linked to changes in the androgenic hormone systems that underlie it. We show that the emergence of this rare display in unrelated anuran taxa is marked by a robust increase in the expression of androgen receptor (AR) messenger RNA in the musculature that actuates leg and foot movements, but we find no evidence of changes in the abundance of AR expression in these frogs' central nervous systems. Meanwhile, the magnitude of the evolutionary change in muscular AR and its association with the origin of foot-flagging differ among clades, suggesting that these variables evolve together in a mosaic fashion. Finally, while gestural displays do differ between species, variation in the complexity of a foot-flagging routine does not predict differences in muscular AR. Altogether, these findings suggest that androgen-muscle interactions provide a conduit for convergence in sexual display behavior, potentially providing a path of least resistance for the evolution of motor performance.
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10
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Lipshutz SE, Rosvall KA. Nesting strategy shapes territorial aggression but not testosterone: A comparative approach in female and male birds. Horm Behav 2021; 133:104995. [PMID: 34000663 DOI: 10.1016/j.yhbeh.2021.104995] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 03/19/2021] [Accepted: 04/29/2021] [Indexed: 11/21/2022]
Abstract
Our understanding of the proximate and ultimate mechanisms shaping competitive reproductive phenotypes primarily stems from research on male-male competition for mates, even though competition is widespread in both sexes. We evaluate the hypothesis that the restricted nature of a resource required for reproduction, i.e. nest site, is a key variable driving territorial competition and testosterone secretion in female and male birds. Obligate secondary cavity-nesting has evolved repeatedly across avian lineages, providing a useful comparative context to explore how competition over limited nest cavities shapes aggression and its underlying mechanisms across species. Although evidence from one or another cavity-nesting species suggests that territorial aggression is adaptive in both females and males, this has not yet been tested in a comparative framework. We predicted that cavity-nesting generates more robust territorial aggression, in comparison to close relatives with less restrictive nesting strategies. Our focal species were two obligate secondary cavity-nesting species and two related species with more flexible nesting strategies in the same avian family: tree swallow (Tachycineta bicolor) vs. barn swallow (Hirundo rustica); Eastern bluebird (Sialia sialis) vs. American robin (Turdus migratorius). We assayed conspecific aggression using simulated territorial intrusion and found that cavity-nesting species displayed greater territorial aggression than their close relatives. This pattern held for both females and males. Because territorial aggression is often associated with elevated testosterone, we also hypothesized that cavity-nesting species would exhibit higher testosterone levels in circulation. However, cavity-nesting species did not have higher testosterone in circulation for either sex, despite some correlative evidence that testosterone is associated with higher rates of physical attack in female tree swallows. Our focus on a context that is relevant to both sexes - competition over essential breeding resources - provides a useful framework for co-consideration of proximate and ultimate drivers of reproductive competition in females and males.
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Affiliation(s)
- Sara E Lipshutz
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
| | - Kimberly A Rosvall
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
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11
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Khalil S, Welklin JF, McGraw KJ, Boersma J, Schwabl H, Webster MS, Karubian J. Testosterone regulates CYP2J19-linked carotenoid signal expression in male red-backed fairywrens ( Malurus melanocephalus). Proc Biol Sci 2020; 287:20201687. [PMID: 32933448 PMCID: PMC7542802 DOI: 10.1098/rspb.2020.1687] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 08/19/2020] [Indexed: 12/12/2022] Open
Abstract
Carotenoid pigments produce most red, orange and yellow colours in vertebrates. This coloration can serve as an honest signal of quality that mediates social and mating interactions, but our understanding of the underlying mechanisms that control carotenoid signal production, including how different physiological pathways interact to shape and maintain these signals, remains incomplete. We investigated the role of testosterone in mediating gene expression associated with a red plumage sexual signal in red-backed fairywrens (Malurus melanocephalus). In this species, males within a single population can flexibly produce either red/black nuptial plumage or female-like brown plumage. Combining correlational analyses with a field-based testosterone implant experiment and quantitative polymerase chain reaction, we show that testosterone mediates expression of carotenoid-based plumage in part by regulating expression of CYP2J19, a ketolase gene associated with ketocarotenoid metabolism and pigmentation in birds. This is, to our knowledge, the first time that hormonal regulation of a specific genetic locus has been linked to carotenoid production in a natural context, revealing how endocrine mechanisms produce sexual signals that shape reproductive success.
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Affiliation(s)
- Sarah Khalil
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA
| | - Joseph F. Welklin
- Macaulay Library, Cornell Laboratory of Ornithology, Ithaca, NY, USA
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| | - Kevin J. McGraw
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Jordan Boersma
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Hubert Schwabl
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Michael S. Webster
- Macaulay Library, Cornell Laboratory of Ornithology, Ithaca, NY, USA
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
| | - Jordan Karubian
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA
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12
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Scheun J, Neller S, Bennett NC, Kemp LV, Ganswindt A. Endocrine correlates of gender and throat coloration in the southern ground-hornbill (Bucorvus leadbeateri). Integr Zool 2020; 16:189-201. [PMID: 32761760 DOI: 10.1111/1749-4877.12478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The southern ground-hornbill (SGH) is a cooperatively breeding bird endemic to eastern and southern Africa, but is endangered in its southern distributional range. The national conservation restoration program harvests redundant chicks for captive breeding and reintroduction; with sexing and social grouping of the species evaluated by throat-skin coloration, with adult males displaying a completely red color compared to dark blue within the red observed in adult females. However, recent findings indicate that dominant and subordinate adult males exhibit patches of blue throat-skin. To optimize SGH management practices, it is vital to determine the role of red and blue coloration, as well as the possible drivers thereof. As a prerequisite, an enzyme immunoassay for monitoring fecal androgen metabolite (fAM) concentrations in SGH was established. Following this, fresh fecal samples were collected from 78 SGH, of various demographics and origin, across 12 captive institutions, to determine whether fAM concentrations differ between blue (B), partially blue (sB), and fully red (R) throat-skin colored SGH. Furthermore, fAM concentrations were compared between males housed in different social groups of different age and sex classes. Individual median fAM concentrations of B, sB, and R adult males did not differ significantly but were considerably higher in B and sB males compared to R males. Social dynamics within captivity, for example, dominance, played no role as a driver of male gonadal activity or throat skin coloration. The results of the study indicate that androgens and apparent social dynamics are not primary determinants of throat coloration in male SGH.
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Affiliation(s)
- Juan Scheun
- Department of Life and Consumer Sciences, University of South Africa, South Africa.,Biodiversity Research Services, National Zoological Gardens, South Africa.,Mammal Research Institute, Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
| | - Sophie Neller
- Mammal Research Institute, Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.,Mabula Ground Hornbill Project/ IUCN Hornbill Specialist Group, Bela-Bela, South Africa
| | - Nigel C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
| | - Lucy V Kemp
- Mabula Ground Hornbill Project/ IUCN Hornbill Specialist Group, Bela-Bela, South Africa.,Department of Applied Behavioural Ecology & Ecosystem Research, University of South Africa, South Africa
| | - Andre Ganswindt
- Biodiversity Research Services, National Zoological Gardens, South Africa.,Mammal Research Institute, Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.,Endocrine Research Laboratory, Department of Anatomy & Physiology, Faculty of Veterinary Science, University of Pretoria, South Africa
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13
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Abstract
Many animals differentially express behaviours across the annual cycle as life stages are coordinated with seasonal environmental conditions. Understanding of the mechanistic basis of such seasonal changes in behaviour has traditionally focused on the role of changes in circulating hormone levels. However, it is increasingly apparent that other endocrine regulation mechanisms such as changes in local hormone synthesis and receptor abundance also play a role. Here I review what is known about seasonal changes in steroid hormone receptor abundance in relation to seasonal behaviour in vertebrates. I find that there is widespread, though not ubiquitous, seasonal variation in the expression of steroid hormone receptors in the brain, with such variation being best documented in association with courtship, mating and aggression. The most common pattern of seasonal variation is for there to be upregulation of sex steroid receptors with the expression of courtship and mating behaviours, when circulating hormone levels are also high. Less well-documented are cases in which seasonal increases in receptor expression could compensate for low circulating hormone levels or seasonal downregulation that could serve a protective function. I conclude by identifying important directions for future research.
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Affiliation(s)
- Heather E Watts
- School of Biological Sciences, and Center for Reproductive Biology, Washington State University, Pullman, WA, USA
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14
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Ball GF, Balthazart J. The neuroendocrine integration of environmental information, the regulation and action of testosterone and the challenge hypothesis. Horm Behav 2020; 123:104574. [PMID: 31442427 DOI: 10.1016/j.yhbeh.2019.104574] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 08/14/2019] [Accepted: 08/19/2019] [Indexed: 11/21/2022]
Abstract
The authors of the original challenge hypothesis proposed influential hypotheses concerning the relationship between testosterone concentrations in the blood and aggressive social behaviors. Many of the key observations were made in avian species studied in the wild and in captivity. In this review we evaluate some remaining questions about the ideas discussed in the challenge hypothesis from a neuroendocrine perspective. For example, a rise in testosterone in response to a social aggressive stimulus might involve complex social information being processed by the brain and an appropriate signal sent to the gonadotrophin-releasing hormone (GnRH) neuronal system. Alternatively, social stimuli could more directly stimulate the testis and testosterone release via sympathetic innervation of the testis though such pathways have not been linked to a response to social behaviors. The social behavior decision network in the brain seems to play a key role in the regulation of aggressive behavior but how sensory information concerning aggressive behaviors is interpreted appropriately, processed by the social decision network and sent to the GnRH system is still not well understood. There are continuing questions about the extensive species variation in whether an increase in testosterone occurs in response to a territorial challenge, what its function might be and whether increases in testosterone are necessary to activate morphological changes, or the expression of sexual and aggressive behaviors associated with successful reproduction.
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Affiliation(s)
- Gregory F Ball
- Department of Psychology, University of Maryland, College Park, MD 201742, USA.
| | - Jacques Balthazart
- Neuroendocrinology Unit, GIGA Neurosciences, University of Liège, 15 avenue Hippocrate (B36), 4000 Liège, Belgium
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Tobiansky DJ, Fuxjager MJ. Sex Steroids as Regulators of Gestural Communication. Endocrinology 2020; 161:5822602. [PMID: 32307535 PMCID: PMC7316366 DOI: 10.1210/endocr/bqaa064] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/16/2020] [Indexed: 12/13/2022]
Abstract
Gestural communication is ubiquitous throughout the animal kingdom, occurring in species that range from humans to arthropods. Individuals produce gestural signals when their nervous system triggers the production of limb and body movement, which in turn functions to help mediate communication between or among individuals. Like many stereotyped motor patterns, the probability of a gestural display in a given social context can be modulated by sex steroid hormones. Here, we review how steroid hormones mediate the neural mechanisms that underly gestural communication in humans and nonhumans alike. This is a growing area of research, and thus we explore how sex steroids mediate brain areas involved in language production, social behavior, and motor performance. We also examine the way that sex steroids can regulate behavioral output by acting in the periphery via skeletal muscle. Altogether, we outline a new avenue of behavioral endocrinology research that aims to uncover the hormonal basis for one of the most common modes of communication among animals on Earth.
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Affiliation(s)
- Daniel J Tobiansky
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island
- Correspondence: Daniel J. Tobiansky, Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912.
| | - Matthew J Fuxjager
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island
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Ketterson ED. What Do Ecology, Evolution, and Behavior Have in Common? The Organism in the Middle. Am Nat 2020; 196:103-118. [PMID: 32673095 DOI: 10.1086/709699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Biologists who publish in The American Naturalist are drawn to its unifying mission of covering research in the fields of ecology, evolution, behavior, and integrative biology. Presented here is one scientist's attempt to straddle these fields by focusing on a single organism. It is also an account of how time spent in the field stimulates a naturalist to wonder "why did that animal just do that?" and how research is guided by chance and intention interacting with the scientific literature and the people one meets along the way. With respect to the science, the examples come from bird migration, hormones and their connection to phenotypic integration, sexual and natural selection, and urban ecology. They also come from research on the impact of environmental change on the timing of reproduction and the potential for allochrony in migratory species to influence population divergence.
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Schuppe ER, Miles MC, Fuxjager MJ. Evolution of the androgen receptor: Perspectives from human health to dancing birds. Mol Cell Endocrinol 2020; 499:110577. [PMID: 31525432 DOI: 10.1016/j.mce.2019.110577] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/04/2019] [Accepted: 09/09/2019] [Indexed: 12/23/2022]
Abstract
Androgenic hormones orchestrate the development and activation of diverse reproductive phenotypes across vertebrates. Although extensive work investigates how selection for these traits modifies individual elements of this signaling system (e.g., hormone or androgen receptor [AR] levels), we know less about natural variation in the AR sequence across vertebrates. Our knowledge of AR sequence mutations is largely limited to work in human patients or cell-lines, providing a framework to contextualize single mutations at the expense of evolutionary timescale. Here we unite both perspectives in a review that explores the functional significance of AR on a domain-by-domain basis, using existing knowledge to highlight how and why each region might evolve. We then examine AR sequence variation on different timescales by examining sequence variation in clades originating in the Cambrian (vertebrates; >500 mya) and Cretaceous (birds; >65 mya). In each case, we characterize how the receptor has changed over time and discuss which regions are most likely to evolve in response to selection. Overall, domains that are required for androgenic signaling to function (e.g., DNA- and ligand-binding) tend to be conserved. Meanwhile, areas that interface with co-regulatory molecules can exhibit notable variation even between closely related species. We propose that accumulating mutations in regulatory regions is one way that AR structure might act as a substrate for selection to guide the evolution of reproductive traits. By synthesizing literature across disciplines and highlighting the evolutionary potential of specific AR regions, we hope to inspire new avenues of integrative research into endocrine system evolution.
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Affiliation(s)
- Eric R Schuppe
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
| | - Meredith C Miles
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA
| | - Matthew J Fuxjager
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA.
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