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Bolton PE, Ryder TB, Dakin R, Houtz JL, Moore IT, Balakrishnan CN, Horton BM. Neurogenomic landscape associated with status-dependent cooperative behaviour. Mol Ecol 2024:e17327. [PMID: 38511765 DOI: 10.1111/mec.17327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 01/04/2024] [Accepted: 03/07/2024] [Indexed: 03/22/2024]
Abstract
The neurogenomic mechanisms mediating male-male reproductive cooperative behaviours remain unknown. We leveraged extensive transcriptomic and behavioural data on a neotropical bird species (Pipra filicauda) that performs cooperative courtship displays to understand these mechanisms. In this species, the cooperative display is modulated by testosterone, which promotes cooperation in non-territorial birds, but suppresses cooperation in territory holders. We sought to understand the neurogenomic underpinnings of three related traits: social status, cooperative display behaviour and testosterone phenotype. To do this, we profiled gene expression in 10 brain nuclei spanning the social decision-making network (SDMN), and two key endocrine tissues that regulate social behaviour. We associated gene expression with each bird's behavioural and endocrine profile derived from 3 years of repeated measures taken from free-living birds in the Ecuadorian Amazon. We found distinct landscapes of constitutive gene expression were associated with social status, testosterone phenotype and cooperation, reflecting the modular organization and engagement of neuroendocrine tissues. Sex-steroid and neuropeptide signalling appeared to be important in mediating status-specific relationships between testosterone and cooperation, suggesting shared regulatory mechanisms with male aggressive and sexual behaviours. We also identified differentially regulated genes involved in cellular activity and synaptic potentiation, suggesting multiple mechanisms underpin these genomic states. Finally, we identified SDMN-wide gene expression differences between territorial and floater males that could form the basis of 'status-specific' neurophysiological phenotypes, potentially mediated by testosterone and growth hormone. Overall, our findings provide new, systems-level insights into the mechanisms of cooperative behaviour and suggest that differences in neurogenomic state are the basis for individual differences in social behaviour.
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Affiliation(s)
- Peri E Bolton
- Department of Biology, East Carolina University, Greenville, North Carolina, USA
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, USA
| | - T Brandt Ryder
- Migratory Bird Center, Smithsonian National Zoological Park, Washington, District of Columbia, USA
- Bird Conservancy of the Rockies, Fort Collins, Colorado, USA
| | - Roslyn Dakin
- Migratory Bird Center, Smithsonian National Zoological Park, Washington, District of Columbia, USA
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Jennifer L Houtz
- Department of Biology, Millersville University, Millersville, Pennsylvania, USA
- Department of Biology, Allegheny College, Meadville, Pennsylvania, USA
| | - Ignacio T Moore
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | | | - Brent M Horton
- Department of Biology, Millersville University, Millersville, Pennsylvania, USA
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2
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Mbiydzenyuy NE, Joanna Hemmings SM, Shabangu TW, Qulu-Appiah L. Exploring the influence of stress on aggressive behavior and sexual function: Role of neuromodulator pathways and epigenetics. Heliyon 2024; 10:e27501. [PMID: 38486749 PMCID: PMC10937706 DOI: 10.1016/j.heliyon.2024.e27501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 02/29/2024] [Accepted: 02/29/2024] [Indexed: 03/17/2024] Open
Abstract
Stress is a complex and multifaceted phenomenon that can significantly influence both aggressive behavior and sexual function. This review explores the intricate relationship between stress, neuromodulator pathways, and epigenetics, shedding light on the various mechanisms that underlie these connections. While the role of stress in both aggression and sexual behavior is well-documented, the mechanisms through which it exerts its effects are multifarious and not yet fully understood. The review begins by delving into the potential influence of stress on the Hypothalamic-Pituitary-Adrenal (HPA) axis, glucocorticoids, and the neuromodulators involved in the stress response. The intricate interplay between these systems, which encompasses the regulation of stress hormones, is central to understanding how stress may contribute to aggressive behavior and sexual function. Several neuromodulator pathways are implicated in both stress and behavior regulation. We explore the roles of norepinephrine, serotonin, oxytocin, and androgens in mediating the effects of stress on aggression and sexual function. It is important to distinguish between general sexual behavior, sexual motivation, and the distinct category of "sexual aggression" as separate constructs, each necessitating specific examination. Additionally, epigenetic mechanisms emerge as crucial factors that link stress to changes in gene expression patterns and, subsequently, to behavior. We then discuss how epigenetic modifications can occur in response to stress exposure, altering the regulation of genes associated with stress, aggression, and sexual function. While numerous studies support the association between epigenetic changes and stress-induced behavior, more research is necessary to establish definitive links. Throughout this exploration, it becomes increasingly clear that the relationship between stress, neuromodulator pathways, and epigenetics is intricate and multifaceted. The review emphasizes the need for further research, particularly in the context of human studies, to provide clinical significance and to validate the existing findings from animal models. By better understanding how stress influences aggressive behavior and sexual function through neuromodulator pathways and epigenetic modifications, this research aims to contribute to the development of innovative protocols of precision medicine and more effective strategies for managing the consequences of stress on human behavior. This may also pave way for further research into risk factors and underlying mechanisms that may associate stress with sexual aggression which finds application not only in neuroscience, but also law, ethics, and the humanities in general.
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Affiliation(s)
- Ngala Elvis Mbiydzenyuy
- Basic Science Department, School of Medicine, Copperbelt University, P.O Box 71191, Ndola, Zambia
- Division of Medical Physiology, Biomedical Science Research Institute, Stellenbosch University, Private Bag X1, Matieland, 7602, Cape Town South Africa
| | - Sian Megan Joanna Hemmings
- Division of Molecular Biology & Human Genetics, Biomedical Science Research Institute, Stellenbosch University, Private Bag X1, Matieland, 7602, Cape Town South Africa
| | - Thando W. Shabangu
- Division of Medical Physiology, Biomedical Science Research Institute, Stellenbosch University, Private Bag X1, Matieland, 7602, Cape Town South Africa
| | - Lihle Qulu-Appiah
- Division of Medical Physiology, Biomedical Science Research Institute, Stellenbosch University, Private Bag X1, Matieland, 7602, Cape Town South Africa
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3
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Schuett GW, Peterson KH, Powell AR, Taylor JD, Alexander JR, Lappin AK. Female-female aggression in the Gila monster ( Heloderma suspectum). ROYAL SOCIETY OPEN SCIENCE 2023; 10:221466. [PMID: 37181791 PMCID: PMC10170349 DOI: 10.1098/rsos.221466] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 04/14/2023] [Indexed: 05/16/2023]
Abstract
Historically, the role of aggression in the social lives of animals overwhelmingly focused on males. In recent years, however, female-female aggression in vertebrates, particularly lizards, has received increasing attention. This growing body of literature shows both similarities and differences to aggressive behaviours between males. Here, we document female-female aggression in captive Gila monsters (Heloderma suspectum). Based on four unique dyadic trials (eight adult female subjects), we developed a qualitative ethogram. Unexpected and most intriguing were the prevalence and intensity of aggressive acts that included brief and sustained biting, envenomation, and lateral rotation (i.e. rolling of body while holding onto opponent with closed jaws). Given specific behavioural acts (i.e. biting) and the results of bite-force experiments, we postulate that osteoderms (bony deposits in the skin) offer some degree of protection and reduce the likelihood of serious injury during female-female fights. Male-male contests in H. suspectum, in contrast, are more ritualized, and biting is rarely reported. Female-female aggression in other lizards has a role in territoriality, courtship tactics, and nest and offspring guarding. Future behavioural research on aggression in female Gila monsters is warranted to test these and other hypotheses in the laboratory and field.
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Affiliation(s)
- Gordon W. Schuett
- Department of Biology | Neuroscience Institute, Georgia State University, Atlanta, GA, USA
- Chiricahua Desert Museum, Rodeo, NM, USA
| | | | - Anthony R. Powell
- Biological Sciences Department, California State Polytechnic University, Pomona, CA, USA
| | - John D. Taylor
- Biological Sciences Department, California State Polytechnic University, Pomona, CA, USA
| | - Jennifer R. Alexander
- Biological Sciences Department, California State Polytechnic University, Pomona, CA, USA
| | - A. Kristopher Lappin
- Biological Sciences Department, California State Polytechnic University, Pomona, CA, USA
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4
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Hoops D, Whiting MJ, Keogh JS. A Smaller Habenula is Associated with Increasing Intensity of Sexual Selection. BRAIN, BEHAVIOR AND EVOLUTION 2022; 97:265-273. [PMID: 34983044 DOI: 10.1159/000521750] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 12/18/2021] [Indexed: 11/19/2022]
Abstract
The habenula is a small structure in the brain that acts as a relay station for neural information, helping to modulate behaviour in response to variable and unpredictable stimuli. Broadly, it is evolutionarily conserved in structure and connectivity across vertebrates and is the most prominent bilaterally asymmetric structure in the brain. Nonetheless, comparative evolutionary studies of the habenula are virtually non-existent. Here, we examine the volumes of the medial and lateral habenular subregions, in both hemispheres, across a group of Australian agamid lizards in the genus Ctenophorus. In males, we found bilaterally asymmetrical selection on the lateral habenula to become smaller with increasing intensity of sexual selection, possibly as a mechanism to increase aggressive responses. In females, we found bilaterally symmetrical selection on both the medial and lateral subregions to become smaller with increasing sexual selection. This is consistent with sexual selection increasing motivation to reproduce and the habenula's well-characterized role in controlling and modifying responses to rewarding stimuli. However, as there are currently no studies addressing habenular function in reptiles, it is difficult to draw more precise conclusions. As has happened recently in biomedical neuroscience, it is time for the habenula to receive greater attention in evolutionary neuroscience.
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Affiliation(s)
- Daniel Hoops
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia.,Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Martin J Whiting
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - J Scott Keogh
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia
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5
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LaDage LD, Yu T, Zani PA. Higher Rate of Male Sexual Displays Correlates with Larger Ventral Posterior Amygdala Volume and Neuron Soma Volume in Wild-Caught Common Side-Blotched Lizards, Uta stansburiana. BRAIN, BEHAVIOR AND EVOLUTION 2022; 97:298-308. [PMID: 35537399 DOI: 10.1159/000524915] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 04/28/2022] [Indexed: 06/14/2023]
Abstract
Several areas of the vertebrate brain are involved in facilitating and inhibiting the production of sexual behaviors and displays. In the laboratory, a higher rate of sexual displays is correlated with a larger ventral posterior amygdala (VPA), an area of the brain involved in the expression of sexual display behaviors, as well as larger VPA neuronal somas. However, it remains unclear if individuals in the field reflect similar patterns, as there are likely many more selective pressures in the field that may also modulate the VPA architecture. In this study, we examined variation in VPA volume and neuron soma volume in wild-caught common side-blotched lizards (Uta stansburiana) from two different populations. In a population from Nevada, males experience high predation pressure and have decreased sexual display rates during the breeding season, whereas a population in Oregon has lower levels of predation and higher rates of male sexual displays. We found that wild-caught males from the population with lower display rates also exhibited decreased VPA volume and VPA neuron cell soma volume, which may suggest that decreased display rate, possibly due to increased predation rate, covaries with VPA attributes.
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Affiliation(s)
- Lara D LaDage
- Division of Mathematics & Natural Sciences, Penn State Altoona, Altoona, Pennsylvania, USA
| | - Tracy Yu
- Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Peter A Zani
- Department of Biology, University of Wisconsin - Stevens Point, Stevens Point, Wisconsin, USA
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6
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Kabelik D, Julien AR, Waddell BR, Batschelett MA, O'Connell LA. Aggressive but not reproductive boldness in male green anole lizards correlates with baseline vasopressin activity. Horm Behav 2022; 140:105109. [PMID: 35066329 DOI: 10.1016/j.yhbeh.2022.105109] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 12/20/2021] [Accepted: 01/04/2022] [Indexed: 11/18/2022]
Abstract
Across species, individuals within a population differ in their level of boldness in social encounters with conspecifics. This boldness phenotype is often stable across both time and social context (e.g., reproductive versus agonistic encounters). Various neural and hormonal mechanisms have been suggested as underlying these stable phenotypic differences, which are often also described as syndromes, personalities, and coping styles. Most studies examining the neuroendocrine mechanisms associated with boldness examine subjects after they have engaged in a social interaction, whereas baseline neural activity that may predispose behavioral variation is understudied. The present study tests the hypotheses that physical characteristics, steroid hormone levels, and baseline variation in Ile3-vasopressin (VP, a.k.a., Arg8-vasotocin) signaling predispose boldness during social encounters. Boldness in agonistic and reproductive contexts was extensively quantified in male green anole lizards (Anolis carolinensis), an established research organism for social behavior research that provides a crucial comparison group to investigations of birds and mammals. We found high stability of boldness across time, and between agonistic and reproductive contexts. Next, immunofluorescence was used to colocalize VP neurons with phosphorylated ribosomal protein S6 (pS6), a proxy marker of neural activity. Vasopressin-pS6 colocalization within the paraventricular and supraoptic nuclei of the hypothalamus was inversely correlated with boldness of aggressive behaviors, but not of reproductive behaviors. Our findings suggest that baseline vasopressin release, rather than solely context-dependent release, plays a role in predisposing individuals toward stable levels of displayed aggression toward conspecifics by inhibiting behavioral output in these contexts.
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Affiliation(s)
- David Kabelik
- Department of Biology & Program in Neuroscience, Rhodes College, Memphis, TN 38112, USA.
| | - Allison R Julien
- Department of Biology & Program in Neuroscience, Rhodes College, Memphis, TN 38112, USA
| | - Brandon R Waddell
- Department of Biology & Program in Neuroscience, Rhodes College, Memphis, TN 38112, USA
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7
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Kabelik D, Julien AR, Ramirez D, O'Connell LA. Social boldness correlates with brain gene expression in male green anoles. Horm Behav 2021; 133:105007. [PMID: 34102460 PMCID: PMC8277760 DOI: 10.1016/j.yhbeh.2021.105007] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 05/01/2021] [Accepted: 05/22/2021] [Indexed: 11/27/2022]
Abstract
Within populations, some individuals tend to exhibit a bold or shy social behavior phenotype relative to the mean. The neural underpinnings of these differing phenotypes - also described as syndromes, personalities, and coping styles - is an area of ongoing investigation. Although a social decision-making network has been described across vertebrate taxa, most studies examining activity within this network do so in relation to exhibited differences in behavioral expression. Our study instead focuses on constitutive gene expression in bold and shy individuals by isolating baseline gene expression profiles that influence social boldness predisposition, rather than those reflecting the results of social interaction and behavioral execution. We performed this study on male green anole lizards (Anolis carolinensis), an established model organism for behavioral research, which provides a crucial comparison group to investigations of birds and mammals. After identifying subjects as bold or shy through repeated reproductive and agonistic behavior testing, we used RNA sequencing to compare gene expression profiles between these groups within various forebrain, midbrain, and hindbrain regions. The ventromedial hypothalamus had the largest group differences in gene expression, with bold males having increased expression of neuroendocrine and neurotransmitter receptor and calcium channel genes compared to shy males. Conversely, shy males express more integrin alpha-10 in the majority of examined regions. There were no significant group differences in physiology or hormone levels. Our results highlight the ventromedial hypothalamus as an important center of behavioral differences across individuals and provide novel candidates for investigations into the regulation of individual variation in social behavior phenotype.
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Affiliation(s)
- David Kabelik
- Department of Biology & Program in Neuroscience, Rhodes College, Memphis, TN 38112, USA.
| | - Allison R Julien
- Department of Biology & Program in Neuroscience, Rhodes College, Memphis, TN 38112, USA
| | - Dave Ramirez
- Department of Biology, Stanford University, Stanford, CA 94305, USA
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Fokidis HB, Brock T. Hurricane Irma induces divergent behavioral and hormonal impacts on an urban and forest population of invasive Anolis lizards: evidence for an urban resilience hypothesis. JOURNAL OF URBAN ECOLOGY 2020. [DOI: 10.1093/jue/juaa031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Hurricanes can have both profound short-term effects on animal populations and serve as long-term drivers of evolutionary change. Animals inhabiting varying habitats may differ in their response to hurricane impacts. Increasing evidence suggests that animals from urban areas exhibit different behavioral and physiological traits compared to rural counterparts, including attenuated hormonal stress responses and a lowered propensity for flight behavior. A unique opportunity was presented when Hurricane Irma hit Florida on 10 September 2017 and interrupted a study of invasive brown anoles (Anolis sagrei) at an urban and a forest. Using data collected before and after Hurricane Irma, we documented that forest anoles exhibited a greater avoidance of people and more male territorial behavior for a longer period of time following the hurricane. Post-hurricane both populations increased corticosterone concentrations post-capture stress, but urban anoles recovered 2 weeks faster than forest conspecifics. A dexamethasone suppression experiment suggested that these population differences were the result of forest anoles having a less effective negative feedback regulating corticosterone secretion. In the brain, forest anoles had higher corticosterone concentrations within the amygdala and parts of the cortex associated with stress than urban lizards. One explanation may be Hurricane Irma brought flooding and debris that altered the landscape leading to behavioral instability, and urban lizards already exhibited ecological adjustments that permitted a more rapid recovery (i.e. the ‘urban resilience’ hypothesis). Testing if urban animals are more resilient to natural disasters can inform conservationists interested in understanding their role in facilitating invasive species expansion and what their increasing presence may indicate for animal populations.
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Affiliation(s)
- H Bobby Fokidis
- Department of Biology, Rollins College, 1000 Holt Avenue, Winter Park, FL 32789-4499, USA
| | - Taylor Brock
- Department of Biology, Rollins College, 1000 Holt Avenue, Winter Park, FL 32789-4499, USA
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9
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Bruinjé AC, Coelho FEA, Paiva TMA, Costa GC. Aggression, color signaling, and performance of the male color morphs of a Brazilian lizard (Tropidurus semitaeniatus). Behav Ecol Sociobiol 2019. [DOI: 10.1007/s00265-019-2673-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Fokidis HB, Ma C, Radin B, Prior NH, Adomat HH, Guns ES, Soma KK. Neuropeptide Y and orexin immunoreactivity in the sparrow brain coincide with seasonal changes in energy balance and steroids. J Comp Neurol 2018; 527:347-361. [DOI: 10.1002/cne.24535] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 08/22/2018] [Accepted: 08/27/2018] [Indexed: 02/06/2023]
Affiliation(s)
| | - Chunqi Ma
- Department of Psychology; University of British Columbia; Vancouver British Columbia Canada
| | - Benjamin Radin
- Department of Biology; Rollins College; Winter Park Florida
| | - Nora H. Prior
- Department of Psychology; University of British Columbia; Vancouver British Columbia Canada
- Program in Neuroscience and Cognitive Neuroscience; University of Maryland; College Park Maryland
| | - Hans H. Adomat
- The Prostate Centre; Vancouver General Hospital; Vancouver British Columbia Canada
| | - Emma S. Guns
- The Prostate Centre; Vancouver General Hospital; Vancouver British Columbia Canada
- Department of Urological Sciences; University of British Columbia; Vancouver British Columbia Canada
| | - Kiran K. Soma
- Department of Psychology; University of British Columbia; Vancouver British Columbia Canada
- Graduate Program in Neuroscience; University of British Columbia; Vancouver British Columbia Canada
- Djavad Mowafaghian Centre for Brain Health; University of British Columbia; Vancouver British Columbia Canada
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11
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Golinski A, Kubička L, John-Alder H, Kratochvíl L. Elevated testosterone is required for male copulatory behavior and aggression in Madagascar ground gecko (Paroedura picta). Gen Comp Endocrinol 2014; 205:133-41. [PMID: 24852349 DOI: 10.1016/j.ygcen.2014.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 05/01/2014] [Accepted: 05/06/2014] [Indexed: 11/22/2022]
Abstract
Elevated levels of gonadal androgens are often required for the expression of male-specific behavioral and morphological traits in all classes of vertebrates, including reptiles. Here, we tested the role of male gonadal androgens in the control of male sexual behavior, aggressive behavior, and size of the hemipenes in the gecko Paroedura picta. We performed hormonal manipulations involving castration with and without testosterone (T) replacement in males and application of exogenous T and ovariectomy in females. Castration suppressed sexual behavior and hemipenes size in males, and these effects were fully rescued by exogenous T. Sexual behavior and growth of the hemipenes were masculinized by male-typical levels of T in females, while ovariectomized females retained female-typical expression of these traits. These results indicate that the development of male sexual behavior in adult females does not require early or pubertal organization. Elevated T increased the likelihood of aggressive behavior directed toward a male intruder, but aggression occurred only rarely. Elevated T is necessary and sufficient for enlargement of the hemipenes and the expression of male sexual behavior in both males and females of Paroedura picta. In contrast to sexual behavior, the expression of aggressive behavior is apparently more dependent on other factors in addition to T itself.
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Affiliation(s)
- Alison Golinski
- Graduate Program in Endocrinology and Animal Biosciences, Rutgers University, 84 Lipman Drive, New Brunswick, NJ 08901, USA
| | - Lukáš Kubička
- Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, 128 43 Praha 2, Czech Republic.
| | - Henry John-Alder
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, 128 43 Praha 2, Czech Republic
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12
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Hoffmann F, Kloas W. The synthetic progestogen, Levonorgestrel, but not natural progesterone, affects male mate calling behavior of Xenopus laevis. Gen Comp Endocrinol 2012; 176:385-90. [PMID: 22391239 DOI: 10.1016/j.ygcen.2012.02.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 02/09/2012] [Accepted: 02/10/2012] [Indexed: 12/19/2022]
Abstract
Worldwide, more than 100 million women use hormonal contraceptives, which act through progestogenic modes of action. These man-made hormones can enter the aquatic environment as they are excreted via feces and urine. Xeno-progestins are able to interfere with the endocrine system of female aquatic vertebrates impairing oogenesis and reproduction. However, data on progestogenic effects on reproductive behavior of male aquatic vertebrates are lacking. To evaluate whether progestins affect the mating behavior of male Xenopus laevis, we exposed male frogs to three environmentally relevant concentrations (10(-7) M, 10(-8) M and 10(-10) M) of the synthetic progestin Levonorgestrel (LNG) and the corresponding natural steroid progesterone (PRG), respectively. LNG at all exposure concentrations increased the proportions of advertisement calling, indicating a sexually aroused state of the males. Furthermore LNG at 10(-7) M decreased the relative proportions of rasping, a call type indicating a sexually unaroused state of the male. PRG, on the other hand, did not affect any of those parameters. Temporal and spectral features of the advertisement call itself were not affected by any of the two exposure treatments. Since LNG exhibits slight androgenic activity, the results suggest that LNG effects on male mate calling behavior of X. laevis are due to its moderate androgenic but not to its progestogenic activities. However, although males' sexual arousal seems to be enhanced by LNG, the adverse effects of LNG on female reproduction presumably outweigh these enhancing effects and LNG exposure nonetheless might result in reduced reproductive success of these animals.
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Affiliation(s)
- Frauke Hoffmann
- Department of Ecophysiology and Aquaculture, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany.
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13
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Wade J. Relationships among hormones, brain and motivated behaviors in lizards. Horm Behav 2011; 59:637-44. [PMID: 20816970 DOI: 10.1016/j.yhbeh.2010.08.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 08/25/2010] [Indexed: 11/22/2022]
Abstract
Lizards provide a rich opportunity for investigating the mechanisms associated with arousal and the display of motivated behaviors. They exhibit diverse mating strategies and modes of conspecific communication. This review focuses on anole lizards, of which green anoles (Anolis carolinensis) have been most extensively studied. Research from other species is discussed in that context. By considering mechanisms collectively, we can begin to piece together neural and endocrine factors mediating the stimulation of sexual and aggressive behaviors in this group of vertebrates.
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Affiliation(s)
- Juli Wade
- Michigan State University, Department of Psychology, East Lansing, MI 48824, USA.
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14
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O’Connell LA, Ding JH, Ryan MJ, Hofmann HA. Neural distribution of the nuclear progesterone receptor in the túngara frog, Physalaemus pustulosus. J Chem Neuroanat 2011; 41:137-47. [DOI: 10.1016/j.jchemneu.2011.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 12/24/2010] [Accepted: 01/03/2011] [Indexed: 11/28/2022]
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15
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O’Connell LA, Matthews BJ, Patel SB, O’Connell JD, Crews D. Molecular characterization and brain distribution of the progesterone receptor in whiptail lizards. Gen Comp Endocrinol 2011; 171:64-74. [PMID: 21185292 PMCID: PMC3041865 DOI: 10.1016/j.ygcen.2010.12.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 12/06/2010] [Accepted: 12/16/2010] [Indexed: 11/21/2022]
Abstract
Progesterone and its nuclear receptor are critical in modulating reproductive physiology and behavior in female and male vertebrates. Whiptail lizards (genus Cnemidophorus) are an excellent model system in which to study the evolution of sexual behavior, as both the ancestral and descendent species exist. Male-typical sexual behavior is mediated by progesterone in both the ancestral species and the descendant all-female species, although the molecular characterization and distribution of the progesterone receptor protein throughout the reptilian brain is not well understood. To better understand the gene targets and ligand binding properties of the progesterone receptor in whiptails, we cloned the promoter and coding sequence of the progesterone receptor and analyzed the predicted protein structure. We next determined the distribution of the progesterone receptor protein and mRNA throughout the brain of Cnemidophorus inornatus and Cnemidophorus uniparens by immunohistochemistry and in situ hybridization. We found the progesterone receptor to be present in many brain regions known to regulate social behavior and processing of stimulus salience across many vertebrates, including the ventral tegmental area, amygdala, nucleus accumbens and several hypothalamic nuclei. Additionally, we quantified immunoreactive cells in the preoptic area and ventromedial hypothalamus in females of both species and males of the ancestral species. We found differences between both species and across ovarian states. Our results significantly extend our understanding of progesterone modulation in the reptilian brain and support the important role of the nuclear progesterone receptor in modulating sexual behavior in reptiles and across vertebrates.
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Affiliation(s)
- Lauren A. O’Connell
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Section of Integrative Biology, University of Texas at Austin, Austin, Texas 78712
| | - Bryan J. Matthews
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Sagar B. Patel
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
| | - Jeremy D. O’Connell
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas 78712
| | - David Crews
- Institute for Cell and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Section of Integrative Biology, University of Texas at Austin, Austin, Texas 78712
- All correspondence and requests for reprints should to addressed to: David Crews, Section of Integrative Biology, University of Texas at Austin, Austin, TX 78712, Phone: 512-471-1113,
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16
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While GM, Isaksson C, McEvoy J, Sinn DL, Komdeur J, Wapstra E, Groothuis TGG. Repeatable intra-individual variation in plasma testosterone concentration and its sex-specific link to aggression in a social lizard. Horm Behav 2010; 58:208-13. [PMID: 20361965 DOI: 10.1016/j.yhbeh.2010.03.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 03/17/2010] [Accepted: 03/23/2010] [Indexed: 11/29/2022]
Abstract
Individual hormone profiles can be important generators of phenotypic variation. Despite this, work on the consequences of hormone profiles has traditionally ignored the large inter-individual variation within natural populations. However, recent research has advocated the need to explicitly consider this variation and address its consequences for selection. One of the key steps in this process is examining repeatability in hormone profiles and their links to behavioral traits under selection. In this study we show that individuals within a free-ranging population of the Australian lizard Egernia whitii exhibit temporal repeatability in their circulating baseline testosterone concentrations as well as their aggressive response towards conspecific intruders. Furthermore, we show significant, sex-specific links between testosterone and aggression. Specifically, testosterone and aggression is negatively linked in males, while there is no relationship in females. As conspecific aggression has significant consequences for fitness-related traits (parental care, mating strategies) in this species, inter-individual variation in testosterone concentrations, through their effects on aggression, could have important implications for individual fitness. We discuss the potential causes and consequences of hormonal repeatability as well as provide explanations for its sex-specific links with aggression. Specifically, we suggest that these patterns are the result of alternative hormonal pathways governing aggression within Egernia and may indicate a decoupling of aggression and testosterone across the sexes.
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Affiliation(s)
- Geoffrey M While
- School of Zoology, Private Bag 05, University of Tasmania, Tasmania, Australia 7001.
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17
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Herrel A, Andrade DV, de Carvalho JE, Brito A, Abe A, Navas C. Aggressive behavior and performance in the Tegu lizard Tupinambis merianae. Physiol Biochem Zool 2010; 82:680-5. [PMID: 19758090 DOI: 10.1086/605935] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Aggression is an important component of behavior in many animals and may be crucial to providing individuals with a competitive advantage when resources are limited. Although much is known about the effects of catecholamines and hormones on aggression, relatively few studies have examined the effects of physical performance on aggression. Here we use a large, sexually dimorphic teiid lizard to test whether individuals that show high levels of physical performance (bite force) are also more aggressive toward a potential threat (i.e., a human approaching the lizard). Our results show that independent of their sex, larger individuals with higher bite forces were indeed more aggressive. Moreover, our data show that individuals with higher bite forces tend to show decreased escape responses and are slower, providing evidence for a trade-off between fight and flight abilities. As bite force increased dramatically with body size, we suggest that large body size and bite force may reduce the threshold for an individual to engage in an aggressive encounter, allowing it to potentially gain or maintain resources and fight off predators while minimizing the risk of injury.
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Affiliation(s)
- Anthony Herrel
- Département d'Ecologie et de Gestion de la Biodiversité, 57 rue Cuvier, Case postale 55, 75231, Paris Cedex 5, France.
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18
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Goodson JL, Kabelik D. Dynamic limbic networks and social diversity in vertebrates: from neural context to neuromodulatory patterning. Front Neuroendocrinol 2009; 30:429-441. [PMID: 19520105 PMCID: PMC2763925 DOI: 10.1016/j.yfrne.2009.05.007] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Revised: 05/11/2009] [Accepted: 05/22/2009] [Indexed: 11/19/2022]
Abstract
Vertebrate animals exhibit a spectacular diversity of social behaviors, yet a variety of basic social behavior processes are essential to all species. These include social signaling; discrimination of conspecifics and sexual partners; appetitive and consummatory sexual behaviors; aggression and dominance behaviors; and parental behaviors (the latter with rare exceptions). These behaviors are of fundamental importance and are regulated by an evolutionarily conserved, core social behavior network (SBN) of the limbic forebrain and midbrain. The SBN encodes social information in a highly dynamic, distributed manner, such that behavior is most strongly linked to the pattern of neural activity across the SBN, not the activity of single loci. Thus, shifts in the relative weighting of activity across SBN nodes can conceivably produce almost limitless variation in behavior, including diversity across species (as weighting is modified through evolution), across behavioral contexts (as weights change temporally) and across behavioral phenotypes (as weighting is specified through heritable and developmental processes). Individual neural loci may also express diverse relationships to behavior, depending upon temporal variations in their functional connectivity to other brain regions ("neural context"). We here review the basic properties of the SBN and show how behavioral variation relates to functional connectivity of the network, and discuss ways in which neuroendocrine factors adjust network activity to produce behavioral diversity. In addition to the actions of steroid hormones on SBN state, we examine the temporally plastic and evolutionarily labile properties of the nonapeptides (the vasopressin- and oxytocin-like neuropeptides), and show how variations in nonapeptide signaling within the SBN serve to promote behavioral diversity across social contexts, seasons, phenotypes and species. Although this diversity is daunting in its complexity, the search for common "organizing principles" has become increasingly fruitful. We focus on multiple aspects of behavior, including sexual behavior, aggression and affiliation, and in each of these areas, we show how broadly relevant insights have been obtained through the examination of behavioral diversity in a wide range of vertebrate taxa.
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Affiliation(s)
- James L Goodson
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
| | - David Kabelik
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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19
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Ketterson ED, Atwell JW, McGlothlin JW. Phenotypic integration and independence: Hormones, performance, and response to environmental change. Integr Comp Biol 2009; 49:365-79. [PMID: 21665827 DOI: 10.1093/icb/icp057] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Hormones coordinate the co-expression of behavioral, physiological, and morphological traits, giving rise to correlations among traits and organisms whose parts work well together. This article considers the implications of these hormonal correlations with respect to the evolution of hormone-mediated traits. Such traits can evolve owing to changes in hormone secretion, hormonal affinity for carrier proteins, rates of degradation and conversion, and interaction with target tissues to name a few. Critically, however, we know very little about whether these changes occur independently or in tandem, and thus whether hormones promote the evolution of tight phenotypic integration or readily allow the parts of the phenotype to evolve independently. For example, when selection favors a change in expression of hormonally mediated characters, is that alteration likely to come about through changes in hormone secretion (signal strength), changes in response to a fixed level of secretion (sensitivity of target tissues), or both? At one extreme, if the phenotype is tightly integrated and only the signal responds via selection's action on one or more hormonally mediated traits, adaptive modification may be constrained by past selection for phenotypic integration. Alternatively, response to selection may be facilitated if multivariate selection favors new combinations that can be easily achieved by a change in signal strength. On the other hand, if individual target tissues readily "unplug" from a hormone signal in response to selection, then the phenotype may be seen as a loose confederation that responds on a trait-by-trait basis, easily allowing adaptive modification, although perhaps more slowly than if signal variation were the primary mode of evolutionary response. Studies reviewed here and questions for future research address the relative importance of integration and independence by comparing sexes, individuals, and populations. Most attention is devoted to the hormone testosterone (T) and a songbird species, the dark-eyed junco (Junco hyemalis).
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Affiliation(s)
- Ellen D Ketterson
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, Indiana, USA.
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20
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Beck LA, Wade J. Morphology and estrogen receptor alpha mRNA expression in the developing green anole forebrain. ACTA ACUST UNITED AC 2009; 311:162-71. [PMID: 19065643 DOI: 10.1002/jez.514] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Sex differences in forebrain morphology arise during development and are often linked to hormonal changes. These dimorphisms frequently occur in regions related to reproductive behaviors. Little is known about the normal ontogeny of reproductive nuclei in the green anole lizard, including whether steroid hormones influence their development. To address this issue, brain region volume, cell density, soma size, and estrogen receptor alpha (ERalpha) mRNA expression were characterized in the preoptic area (POA), ventromedial amygdala (AMY), and ventromedial hypothalamus (VMH) of late embryonic and early post-hatchling anoles. In adulthood, the POA and AMY are associated with male-specific reproductive behaviors and the VMH is implicated in female receptivity. Although soma size decreased in all brain regions with age, brain region volume diminished only in the POA, with a transient sex difference appearing before hatching. Cell density increased with age only in the female AMY. ERalpha mRNA expression was up to four times greater in the developing VMH than POA and AMY, peaking in the VMH around the day of hatching. These results are consistent with the idea that estradiol may influence differentiation of the VMH in particular. However, other factors are likely important to the development of these three brain regions, some of which exert their effects at later developmental stages.
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Affiliation(s)
- Laurel Amanda Beck
- Neuroscience Program, Michigan State University, East Lansing, Michigan 48824, USA.
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21
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Sampedro C, Font E, Desfilis E. Size variation and cell proliferation in chemosensory brain areas of a lizard (Podarcis hispanica): effects of sex and season. Eur J Neurosci 2008; 28:87-98. [PMID: 18662337 DOI: 10.1111/j.1460-9568.2008.06287.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many lizards rely on chemoreception for crucial aspects of their biology, including exploration, prey and predator detection, and intraspecific communication. Here we investigate sex and seasonal variation in size and proliferative activity in chemosensory areas of the lizard brain. We captured adult Iberian wall lizards (Podarcis hispanica) of either sex in the breeding (April) and non-breeding (November) season, injected them with 5-bromo-2'-deoxyuridine (BrdU) and killed them 3 weeks later. We removed the brains, measured the length of the olfactory bulbs, and counted BrdU-labelled cells in the main and accessory olfactory bulbs (MOB, AOB), lateral cortex (LC) and nucleus sphericus (NS). Our results show that, relative to body size, males have larger MOBs and AOBs than females; however, relative to brain size, males have larger AOBs, but not larger MOBs than females. Additionally, males produce more new cells than females in the olfactory bulbs, LC and NS. We failed to detect significant seasonal changes or sex x season interaction in size or proliferative activity in these areas. Sex differences in the addition of newly generated cells--mainly neurons--may be partly responsible for the size differences in chemosensory brain areas. The presence of sexual dimorphism in AOB is expected given the available behavioural evidence, which suggests that males of P. hispanica are more responsive than females to socially relevant chemical stimuli. This is the first demonstration of sexual dimorphism in size and proliferative activity in chemosensory areas of a non-mammalian species.
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Affiliation(s)
- Carlos Sampedro
- Unidad de Etología, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universidad de Valencia, Paterna, Spain.
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