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Shankey NT, Cohen RE. Neural control of reproduction in reptiles. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:307-321. [PMID: 38247297 DOI: 10.1002/jez.2783] [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: 06/30/2023] [Revised: 01/03/2024] [Accepted: 01/04/2024] [Indexed: 01/23/2024]
Abstract
Reptiles display considerable diversity in reproductive behavior, making them great models to study the neuroendocrine control of reproductive behavior. Many reptile species are seasonally breeding, such that they become reproductively active during their breeding season and regress to a nonreproductive state during their nonbreeding season, with this transition often prompted by environmental cues. In this review, we will focus on summarizing the neural and neuroendocrine mechanisms controlling reproductive behavior. Three major areas of the brain are involved in reproductive behavior: the preoptic area (POA), amygdala, and ventromedial hypothalamus (VMH). The POA and VMH are sexually dimorphic areas, regulating behaviors in males and females respectively, and all three areas display seasonal plasticity. Lesions to these areas disrupt the onset and maintenance of reproductive behaviors, but the exact roles of these regions vary between sexes and species. Different hormones influence these regions to elicit seasonal transitions. Circulating testosterone (T) and estradiol (E2) peak during the breeding season and their influence on reproduction is well-documented across vertebrates. The conversion of T into E2 and 5α-dihydrotestosterone can also affect behavior. Melatonin and corticosterone have generally inhibitory effects on reproductive behavior, while serotonin and other neurohormones seem to stimulate it. In general, there is relatively little information on the neuroendocrine control of reproduction in reptiles compared to other vertebrate groups. This review highlights areas that should be considered for future areas of research.
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Affiliation(s)
- Nicholas T Shankey
- Department of Biological Sciences, Minnesota State University, Mankato, Mankato, Minnesota, USA
| | - Rachel E Cohen
- Department of Biological Sciences, Minnesota State University, Mankato, Mankato, Minnesota, USA
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Richardson J, Zuk M. Rethinking same-sex sexual behaviour: male field crickets have broad mating filters. Proc Biol Sci 2023; 290:20230002. [PMID: 37122255 PMCID: PMC10130708 DOI: 10.1098/rspb.2023.0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 03/27/2023] [Indexed: 05/02/2023] Open
Abstract
Same-sex sexual behaviour (SSB) occurs in many animals and is often treated as an anomaly requiring special explanation. One common explanation for SSB is mistaken identity. However, animals make similar 'mistakes' in other contexts-such as attempting to mate with immature individuals or inanimate objects. Framing such behaviours as 'mistakes' risks misinterpreting how animals make flexible mating decisions. Here we make a case for an alternative approach to thinking about SSB by instead considering an individual's mating filter. A broad filter means directing courtship toward anything that resembles a potential mate, whilst a narrow filter means only courting with receptive targets. We illustrate this approach by examining the mating filters of male Pacific field crickets (Teleogryllus oceanicus). We find that males engage in SSB but also misdirect courtship toward juveniles (but not plastic crickets). This finding suggests that SSB is not an anomaly and is better considered alongside other misdirected behaviours. We argue that by viewing misdirected behaviours through the lens of mating filters rather than as 'mistakes' we can build a more nuanced understanding of reproductive behaviour and begin to determine when having a broader mating filter can be advantageous.
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Affiliation(s)
- Jon Richardson
- Department of Ecology, Evolution and Behavior, University of Minnesota, Minneapolis, MN, USA
| | - Marlene Zuk
- Department of Ecology, Evolution and Behavior, University of Minnesota, Minneapolis, MN, USA
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Zeeman AN, Smallegange IM, Steel EB, Groot AT, Stewart KA. Toward an understanding of the chemical ecology of alternative reproductive tactics in the bulb mite (Rhizoglyphus robini). BMC Ecol Evol 2022; 22:5. [PMID: 34998364 PMCID: PMC8742560 DOI: 10.1186/s12862-021-01956-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 12/22/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Under strong sexual selection, certain species evolve distinct intrasexual, alternative reproductive tactics (ARTs). In many cases, ARTs can be viewed as environmentally-cued threshold traits, such that ARTs coexist if their relative fitness alternates over the environmental cue gradient. Surprisingly, the chemical ecology of ARTs has been underexplored in this context. To our knowledge, no prior study has directly quantified pheromone production for ARTs in a male-polymorphic species. Here, we used the bulb mite-in which males are either armed fighters that kill conspecifics, or unarmed scramblers (which have occasionally been observed to induce mating behavior in other males)-as a model system to gain insight into the role of pheromones in the evolutionary maintenance of ARTs. Given that scramblers forgo investment into weaponry, we tested whether scramblers produce higher quantities of the putative female sex-pheromone α-acaridial than fighters, which would improve the fitness of the scrambler phenotype through female mimicry by allowing avoidance of aggression from competitors. To this end, we sampled mites from a rich and a poor nutritional environment and quantified their production of α-acaridial through gas chromatography analysis. RESULTS We found a positive relationship between pheromone production and body size, but males exhibited a steeper slope in pheromone production with increasing size than females. Females exhibited a higher average pheromone production than males. We found no significant difference in slope of pheromone production over body size between fighters and scramblers. However, scramblers reached larger body sizes and higher pheromone production than fighters, providing some evidence for a potential female mimic strategy adopted by large scramblers. Pheromone production was significantly higher in mites from the rich nutritional environment than the poor environment. CONCLUSION Further elucidation of pheromone functionality in bulb mites, and additional inter- and intrasexual comparisons of pheromone profiles are needed to determine if the observed intersexual and intrasexual differences in pheromone production are adaptive, if they are a by-product of allometric scaling, or diet-mediated pheromone production under weak selection. We argue chemical ecology offers a novel perspective for research on ARTs and other complex life-history traits.
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Affiliation(s)
- Adam N Zeeman
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Isabel M Smallegange
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Emily Burdfield Steel
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Astrid T Groot
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Kathryn A Stewart
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
- Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands.
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Ontogenetic colour change of a sexual ornament in males of a damselfly: female mimicry, crypsis or both? Naturwissenschaften 2021; 109:2. [PMID: 34874492 DOI: 10.1007/s00114-021-01775-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/25/2021] [Accepted: 11/29/2021] [Indexed: 10/19/2022]
Abstract
Female mimicry by males is a widespread phenomenon in several taxa and may be involved in aggression avoidance or facilitated access to resources. In early developmental stages, female mimicry may be a mechanism involved in signalling sexual immaturity or, when coupled with strategies related to visual camouflage, may be involved in the avoidance of male-male agonistic interactions. Here, we addressed whether the delayed colour maturation of a sexual ornament in males of Mnesarete pudica damselflies might be a case of crypsis, female mimicry or both. We analysed how conspecifics and predators perceive the pigmented wings of juvenile males by contrasting the wing spectra against a savannah background and the wings of both juvenile and sexually mature males and females. Our results based on the modelled visual system of conspecifics and predators suggest that the colour maturation of juvenile males may function as both crypsis and female mimicry. We discuss whether these results related to age- and sexual-dichromatism might be a mechanism to avoid unwanted intraspecific interactions or to avoid territorial and aggressive males. We conclude that the female mimicry and crypsis in juvenile males of M. pudica are mechanisms involved in avoidance of predators and unwanted intraspecific interactions, and the signalling of sexual maturity.
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Analyses of Skin Secretions of Vipera ammodytes (Linnaeus, 1758) (Reptilia: Serpentes), with Focus on the Complex Compounds and Their Possible Role in the Chemical Communication. Molecules 2020; 25:molecules25163622. [PMID: 32784906 PMCID: PMC7465031 DOI: 10.3390/molecules25163622] [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: 07/02/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 11/17/2022] Open
Abstract
Snakes rely heavily on chemical cues when foraging, searching for mates, etc. Snakes' sex attractiveness pheromones comprise mainly heavy, semi-volatile compounds such as ketones. Here we investigated the composition of skin secretions of adult Vipera ammodytes (Linnaeus, 1758) individuals. The samples were analyzed by gas chromatography/mass spectrometry and the identification of the compounds was performed using commercial mass spectral libraries and retention times. The relative concentrations of all detected compounds were tested for significant differences between (1) male vs. female live individuals, (2) shed skin vs. live individuals, and (3) pre-reproductive vs. reproductive live individuals. We detected fifty-nine compounds of which six were ketones. Two ketones (2-pentacosanone and 2-heptacosanone) were present in many of the samples and thus may have an important role in the V. ammodytes chemical communication. We did not find significant differences between the relative concentrations of the compounds between male and female individuals (only three compounds are exceptions). Significant differences were found between extracts from shed skins and live individuals and between live pre-reproductive individuals and live reproductive individuals. The results of the study suggest that chemical communication in V. ammodytes involves less compounds in comparison to the known literature data for other species.
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Kelehear C, Shine R. Non-reproductive male cane toads (Rhinella marina) withhold sex-identifying information from their rivals. Biol Lett 2019; 15:20190462. [PMID: 31409244 DOI: 10.1098/rsbl.2019.0462] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A male cane toad (Rhinella marina) that mistakenly clasps another male (rather than a female) in a sexual embrace (amplexus) can be induced to dismount by a male-specific 'release call'. Although that sex-identifying system can benefit both males in that interaction, our standardized tests showed that one-third of male cane toads did not emit release calls when grasped. Most of those silent males were small, had small testes relative to body mass, and had poorly developed secondary sexual characteristics. If emitting a release call is costly (e.g. by attracting predators), a non-reproductive male may benefit by remaining silent; other cues (such as skin rugosity) will soon induce the amplexing male to dismount, and the 'opportunity cost' to being amplexed (inability to search for and clasp a female) is minimal for non-reproductive males. Hence, male toads may inform other males about their sexual identity only when it is beneficial to do so.
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Affiliation(s)
- Crystal Kelehear
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales 2006, Australia.,Department of Biology, Geology & Physical Sciences, Sul Ross State University, Alpine, TX 79832, USA
| | - Richard Shine
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales 2006, Australia.,Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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Weldon PJ. Receiver-error in deception, including mimicry: making the leap from inter- to intraspecific domains. Biol J Linn Soc Lond 2016. [DOI: 10.1111/bij.12905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Paul J. Weldon
- Smithsonian Conservation Biology Institute; National Zoological Park; 1500 Remount Road Front Royal VA 22630 USA
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López-Rull I, Vergara P, Martínez-Padilla J, Fargallo JA. Early constraints in sexual dimorphism: survival benefits of feminized phenotypes. J Evol Biol 2015; 29:231-40. [DOI: 10.1111/jeb.12779] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 10/17/2015] [Accepted: 10/19/2015] [Indexed: 11/30/2022]
Affiliation(s)
- I. López-Rull
- Departamento de Ecología Evolutiva; Museo Nacional de Ciencias Naturales-CSIC; Madrid España
| | - P. Vergara
- Departamento de Ecología Evolutiva; Museo Nacional de Ciencias Naturales-CSIC; Madrid España
| | - J. Martínez-Padilla
- Departamento de Ecología Evolutiva; Museo Nacional de Ciencias Naturales-CSIC; Madrid España
| | - J. A. Fargallo
- Departamento de Ecología Evolutiva; Museo Nacional de Ciencias Naturales-CSIC; Madrid España
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Luo C, Wei C. Intraspecific sexual mimicry for finding females in a cicada: males produce ‘female sounds’ to gain reproductive benefit. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.01.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Apps PJ, Weldon PJ, Kramer M. Chemical signals in terrestrial vertebrates: search for design features. Nat Prod Rep 2015; 32:1131-53. [DOI: 10.1039/c5np00029g] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We review current information on intraspecific chemical signals and search for patterns in signal chemistry among modern terrestrial vertebrates (Amniota), including tortoises, squamate reptiles (amphisbaenians, lizards, and snakes), birds, and mammals.
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Affiliation(s)
- Peter J. Apps
- Paul G. Allen Family Foundation Laboratory for Wildlife Chemistry
- Botswana Predator Conservation Trust
- Maun
- Botswana
| | - Paul J. Weldon
- Smithsonian Conservation Biology Institute
- National Zoological Park
- Front Royal
- USA
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Parker MR, Mason RT. A novel mechanism regulating a sexual signal: the testosterone-based inhibition of female sex pheromone expression in garter snakes. Horm Behav 2014; 66:509-16. [PMID: 25058443 DOI: 10.1016/j.yhbeh.2014.07.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 07/13/2014] [Accepted: 07/14/2014] [Indexed: 11/18/2022]
Abstract
Vertebrates communicate their sex to conspecifics through the use of sexually dimorphic signals, such as ornaments, behaviors and scents. Furthermore, the physiological connection between hormones and secondary sexual signal expression is key to understanding their dimorphism, seasonality and evolution. The red-sided garter snake (Thamnophis sirtalis parietalis) is the only reptile for which a described pheromone currently exists, and because garter snakes rely completely on the sexual attractiveness pheromone for species identification and mate choice, they constitute a unique model species for exploring the relationship between pheromones and the endocrine system. We recently demonstrated that estrogen can activate female pheromone production in male garter snakes. The purpose of this study was to determine the mechanism(s) acting to prevent female pheromone production in males. We found that castrated males (GX) are courted by wild males in the field and produce appreciable amounts of female sex pheromone. Furthermore, pheromone production is inhibited in castrates given testosterone implants (GX+T), suggesting that pheromone production is actively inhibited by the presence of testosterone. Lastly, testosterone supplementation alone (T) increased the production of several saturated methyl ketones in the pheromone but not the unsaturated ketones; this may indicate that saturated ketones are testosterone-activated components of the garter snake's skin lipid milieu. Collectively, our research has shown that pheromone expression in snakes results from two processes: activation by the feminizing steroid estradiol and inhibition by testosterone. We suggest that basal birds and garter snakes share common pathways of activation that modulate crucial intraspecific signals that originate from skin.
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Affiliation(s)
- M Rockwell Parker
- Department of Zoology, Oregon State University, Corvallis, OR 97331, USA; Department of Biology, Washington and Lee University, Lexington, VA 24450, USA.
| | - Robert T Mason
- Department of Zoology, Oregon State University, Corvallis, OR 97331, USA
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13
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Bailey NW, French N. Same-sex sexual behaviour and mistaken identity in male field crickets, Teleogryllus oceanicus. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.08.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Vergara P, Martinez-Padilla J, Fargallo JA. Differential maturation of sexual traits: revealing sex while reducing male and female aggressiveness. Behav Ecol 2012. [DOI: 10.1093/beheco/ars159] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Parker MR, Mason RT. How to make a sexy snake: estrogen activation of female sex pheromone in male red-sided garter snakes. J Exp Biol 2012; 215:723-30. [DOI: 10.1242/jeb.064923] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Vertebrates indicate their genetic sex to conspecifics using secondary sexual signals, and signal expression is often activated by sex hormones. Among vertebrate signaling modalities, the least is known about how hormones influence chemical signaling. Our study species, the red-sided garter snake (Thamnophis sirtalis parietalis), is a model vertebrate for studying hormonal control of chemical signals because males completely rely on the female sex pheromone to identify potential mates among thousands of individuals. How sex hormones can influence the expression of this crucial sexual signal is largely unknown. We created two groups of experimental males for the first experiment: Sham (blank implants) and E2 (17β-estradiol implants). E2 males were vigorously courted by wild males in outdoor bioassays, and in a Y-maze E2 pheromone trails were chosen by wild males over those of small females and were indistinguishable from large female trails. Biochemically, the E2 pheromone blend was similar to that of large females, and it differed significantly from Shams. For the second experiment, we implanted males with 17β-estradiol in 2007 but removed the implants the following year (2008; Removal). That same year, we implanted a new group of males with estrogen implants (Implant). Removal males were courted by wild males in 2008 (implant intact) but not in 2009 (removed). Total pheromone quantity and quality increased following estrogen treatment, and estrogen removal re-established male-typical pheromone blends. Thus, we have shown that estrogen activates the production of female pheromone in adult red-sided garter snakes. This is the first known study to quantify both behavioral and biochemical responses in chemical signaling following sex steroid treatment of reptiles in the activation/organization context. We propose that the homogametic sex (ZZ, male) may possess the same targets for activation of sexual signal production, and the absence of the activator (17β-estradiol in this case) underlies expression of the male phenotype.
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Affiliation(s)
- M. Rockwell Parker
- Department of Zoology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA
| | - Robert T. Mason
- Department of Zoology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA
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Facultative pheromonal mimicry in snakes: “she-males” attract courtship only when it is useful. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1317-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Sternalski A, Mougeot F, Bretagnolle V. Adaptive significance of permanent female mimicry in a bird of prey. Biol Lett 2011; 8:167-70. [PMID: 22072281 DOI: 10.1098/rsbl.2011.0914] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Permanent female mimicry, in which adult males express a female phenotype, is known only from two bird species. A likely benefit of female mimicry is reduced intrasexual competition, allowing female-like males to access breeding resources while avoiding costly fights with typical territorial males. We tested this hypothesis in a population of marsh harriers Circus aeruginosus in which approximately 40 per cent of sexually mature males exhibit a permanent, i.e. lifelong, female plumage phenotype. Using simulated territorial intrusions, we measured aggressive responses of breeding males towards conspecific decoys of females, female-like males and typical males. We show that aggressive responses varied with both the type of decoys and the type of defending male. Typical males were aggressive towards typical male decoys more than they were towards female-like male decoys; female-like male decoys were attacked at a rate similar to that of female decoys. By contrast, female-like males tolerated male decoys (both typical and female-like) and directed their aggression towards female decoys. Thus, agonistic responses were intrasexual in typical males but intersexual in female-like males, indicating that the latter not only look like females but also behave like them when defending breeding resources. When intrasexual aggression is high, permanent female mimicry is arguably adaptive and could be seen as a permanent 'non-aggression pact' with other males.
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Affiliation(s)
- Audrey Sternalski
- Instituto de Investigación en Recursos Cinegéticos (IREC-CSIC-UCLM-JCCM), Ronda de Toledo s/n, Ciudad Real, Spain.
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Castoe TA, Bronikowski AM, Brodie ED, Edwards SV, Pfrender ME, Shapiro MD, Pollock DD, Warren WC. A proposal to sequence the genome of a garter snake (Thamnophis sirtalis). Stand Genomic Sci 2011; 4:257-70. [PMID: 21677863 PMCID: PMC3111982 DOI: 10.4056/sigs.1664145] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Here we develop an argument in support of sequencing a garter snake (Thamnophis sirtalis) genome, and outline a plan to accomplish this. This snake is a common, widespread, nonvenomous North American species that has served as a model for diverse studies in evolutionary biology, physiology, genomics, behavior and coevolution. The anole lizard is currently the only genome sequence available for a non-avian reptile. Thus, the garter snake at this time would be the first available snake genome sequence and as such would provide much needed comparative representation of non-avian reptilian genomes, and would also allow critical new insights for vertebrate comparative genomic studies. We outline the major areas of discovery that the availability of the garter snake genome would enable, and describe a plan for whole-genome sequencing.
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Affiliation(s)
- Todd A. Castoe
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO
- Corresponding Author: Todd A. Castoe,
| | - Anne M. Bronikowski
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA
| | - Edmund D. Brodie
- Department of Biology, University of Virginia, Charlottesville, VA
| | - Scott V. Edwards
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA
| | | | | | - David D. Pollock
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO
| | - Wesley C. Warren
- Genome Sequencing Center, Washington University School of Medicine, St. Louis, MO
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Patterns of tail breakage in the ladder snake (Rhinechis scalaris) reflect differential predation pressure according to body size. ZOOLOGY 2010; 113:269-74. [DOI: 10.1016/j.zool.2010.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 03/16/2010] [Accepted: 03/17/2010] [Indexed: 11/17/2022]
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22
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Social behavior and pheromonal communication in reptiles. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2010; 196:729-49. [DOI: 10.1007/s00359-010-0551-3] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2010] [Revised: 05/14/2010] [Accepted: 06/13/2010] [Indexed: 10/19/2022]
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Aubret F, Shine R. Thermal plasticity in young snakes: how will climate change affect the thermoregulatory tactics of ectotherms? ACTA ACUST UNITED AC 2010; 213:242-8. [PMID: 20038657 DOI: 10.1242/jeb.035931] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Climate change will result in some areas becoming warmer and others cooler, and will amplify the magnitude of year-to-year thermal variation in many areas. How will such changes affect animals that rely on ambient thermal heterogeneity to behaviourally regulate their body temperatures? To explore this question, we raised 43 captive-born tiger snakes Notechis scutatus in enclosures that provided cold (19-22 degrees C), intermediate (19-26 degrees C) or hot (19-37 degrees C) thermal gradients. The snakes adjusted their diel timing of thermoregulatory behaviour so effectively that when tested 14 months later, body temperatures (mean and maximum), locomotor speeds and anti-predator behaviours did not differ among treatment groups. Thus, the young snakes modified their behaviour to compensate for restricted thermal opportunities. Then, we suddenly shifted ambient conditions to mimic year-to-year variation. In contrast to the earlier plasticity, snakes failed to adjust to this change, e.g. snakes raised at cooler treatments but then shifted to hot conditions showed a higher mean body temperature for at least two months after the onset of the new thermal regime. Hence, thermal conditions experienced early in life influenced subsequent thermoregulatory tactics; the mean selected temperature of a snake depended more upon its prior raising conditions than upon its current thermoregulatory opportunities. Behavioural plasticity thus allows snakes to adjust to suboptimal thermal conditions but this plasticity is limited. The major thermoregulatory challenge from global climate change may not be the shift in mean values (to which our young snakes adjusted) but the increased year-to-year variation (with which our snakes proved less able to deal).
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Affiliation(s)
- F Aubret
- Laboratoire d'Ecologie Expérimentale, CNRS à Moulis, 09200 Moulis, France.
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Brischoux F, Bonnet X, Shine R. Kleptothermy: an additional category of thermoregulation, and a possible example in sea kraits (Laticauda laticaudata, Serpentes). Biol Lett 2009; 5:729-31. [PMID: 19656862 DOI: 10.1098/rsbl.2009.0550] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Lacking the capacity for thermogenesis, most ectotherms inhabiting thermally heterogeneous environments rely instead upon exploiting that ambient heterogeneity. In many cases they maintain body temperatures within a narrow range despite massive spatial and temporal variation in ambient conditions. Reliance on diverse thermal opportunities is reflected in specific terms for organisms that bask in sunlight to regulate their temperature (heliotherms), or that press their bodies against warm substrates to facilitate heat flow (thigmotherms), or that rely on large body mass to maintain thermal constancy (gigantothermy). We propose an additional category of thermoregulators: kleptotherms, which regulate their own temperature by 'stealing' heat from other organisms. This concept involves two major conditions: the thermal heterogeneity created by the presence of a warm organism in a cool environment and the selective use of that heterogeneity by another animal to maintain body temperatures at higher (and more stable) levels than would be possible elsewhere in the local area. Kleptothermy occurs in endotherms also, but is usually reciprocal (rather than unilateral as in ectotherms). Thermal monitoring on a small tropical island documents a possible example of kleptothermy, based on high stable temperatures of a sea snake (Laticauda laticaudata) inside a burrow occupied by seabirds.
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Affiliation(s)
- François Brischoux
- Biological Sciences A08, University of Sydney, Sydney, NSW 2006, Australia.
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Whiting MJ, Webb JK, Keogh JS. Flat lizard female mimics use sexual deception in visual but not chemical signals. Proc Biol Sci 2009; 276:1585-91. [PMID: 19324828 PMCID: PMC2660994 DOI: 10.1098/rspb.2008.1822] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 12/23/2008] [Accepted: 01/05/2009] [Indexed: 11/12/2022] Open
Abstract
Understanding what constrains signalling and maintains signal honesty is a central theme in animal communication. Clear cases of dishonest signalling, and the conditions under which they are used, represent an important avenue for improved understanding of animal communication systems. Female mimicry, when certain males take on the appearance of females, is most commonly a male alternative reproductive tactic that is condition-dependent. A number of adaptive explanations for female mimicry have been proposed including avoiding the costs of aggression, gaining an advantage in combat, sneaking copulations with females on the territories of other males, gaining physiological benefits and minimizing the risk of predation. Previous studies of female mimicry have focused on a single mode of communication, although most animals communicate using multiple signals. Male Augrabies flat lizards adopt alternative reproductive tactics in which some males (she-males) mimic the visual appearance of females. We experimentally tested in a wild population whether she-males are able to mimic females using both visual and chemical signals. We tested chemical recognition in the field by removing scent and relabelling females and she-males with either male or female scent. At a distance, typical males (he-males) could not distinguish she-males from females using visual signals, but during close encounters, he-males correctly determined the gender of she-males using chemical signals. She-males are therefore able to deceive he-males using visual but not chemical signals. To effectively deceive he-males, she-males avoid close contact with he-males during which chemical cues would reveal their deceit. This strategy is probably adaptive, because he-males are aggressive and territorial; by mimicking females, she-males are able to move about freely and gain access to females on the territories of resident males.
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Affiliation(s)
- Martin J Whiting
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa.
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Abstract
Female mimics are known from many species, but permanent, non-conditional, alternative mating strategies are only known from an isopod, a fish, a lizard and a bird. The single bird example refers to lek-breeding ruffs Philomachus pugnax, a shorebird for which two strategies (independent and satellite) have been known for over 50 years. Ruffs also provided the single case of an animal with two, rather than three, permanent alternative mating strategies. Here, we describe a rare female-like morph of ruffs: the 'missing' third alternative mating strategy, which we have called 'faeder'. Faeders are slightly larger than females and in late April have testes 2.5 time the size of testes of normal males. On leks in aviaries and in the wild they appear to combine feminine and masculine behaviours. Faeders may represent the ancestral, care-giving, male strategy, but their relatively large testes suggest that currently they behave as sneakers.
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Affiliation(s)
- Joop Jukema
- Haerdawei 628854 AC Oosterbierum, The Netherlands
| | - Theunis Piersma
- Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of GroningenPO Box 14, 9750 AA Haren, The Netherlands
- Department of Marine Ecology and Evolution, Royal Netherlands Institute for Sea Research (NIOZ)PO Box 59, 1790 AB Den Burg, Texel, The Netherlands
- Author for correspondence ()
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Battle of the sexes: forcibly inseminating male garter snakes target courtship to more vulnerable females. Anim Behav 2005. [DOI: 10.1016/j.anbehav.2005.03.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
The storage and utilization of energy plays a critical role in reproductive output for females of many species, including snakes. However, links between energy and reproductive effort in males are less clear. Studies at a communal den of red-sided garter snakes (Thamnophis sirtalis parietalis (Say, 1823)) in Manitoba suggest that energy is critical to reproduction for males as well as females. Males vary substantially in body condition (mass relative to body length) at the time they emerge from winter inactivity. The energy to be expended in courtship is stored in the muscles rather than the "conventional" sites for energy storage in snakes (abdominal fat bodies or liver). A male's reproductive effort (the duration of his residency at courting aggregations near the den) was linked to his energy stores and to the rate of depletion of those stores. Male snakes that emerged from hibernation in better condition, and that lost mass slowly thereafter, remained in courting aggregations near the den for longer periods than did males that emerged in poor condition (i.e., with less energy resources) and (or) lost mass more rapidly. In outdoor arenas, males that engaged in courtship lost mass more rapidly than did males with no courtship opportunities. These data suggest that courtship is energetically expensive for male garter snakes and that the amount of effort that a male invests in reproduction is determined by his energy stores.
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Krohmer RW. The Male Red-sided Garter Snake (Thamnophis sirtalis parietalis): Reproductive Pattern and Behavior. ILAR J 2004. [DOI: 10.1093/ilar.45.1.65] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Confusion within ‘mating balls’ of garter snakes: does misdirected courtship impose selection on male tactics? Anim Behav 2003. [DOI: 10.1006/anbe.2003.2301] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Shine R, Langkilde T, Mason RT. Cryptic Forcible Insemination: Male Snakes Exploit Female Physiology, Anatomy, and Behavior to Obtain Coercive Matings. Am Nat 2003; 162:653-67. [PMID: 14618542 DOI: 10.1086/378749] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2002] [Accepted: 04/22/2003] [Indexed: 11/03/2022]
Abstract
Whether males can inseminate uncooperative females is a central determinant of mating system evolution that profoundly affects the interpretation of phenomena such as multiple mating by females, mate choice, reproductive seasonality, and courtship tactics. Forcible insemination is usually inferred from direct physical battles between the sexes and has been dismissed on intuitive grounds for many kinds of animals. For example, snakes have elongate flexible bodies (making it difficult for a male to restrain a female physically), males are typically smaller than females, and copulation requires female cloacal gaping to enable intromission. Male garter snakes (Thamnophis sirtalis) do not display any overt aggression during courtship and simply lie over the female and exhibit rhythmic pulsating caudocephalic waves of muscular contraction; previous studies have interpreted this behavior as a mechanism for eliciting female receptivity. In contrast, we show that male garter snakes forcibly inseminate females. They do so by taking advantage of specific features of snake physiology, respiratory anatomy, and antipredator behavior. The snake lung extends along most of the body, with the large posterior section (the saccular lung) lacking any respiratory exchange surface. Rhythmic caudocephalic waves by courting male garter snakes push anoxic air from the saccular lung forward and across the respiratory surfaces such that females cannot obtain oxygen. Their stress response involves cloacal gaping, which functions in other contexts to repel predators by extruding feces and musk but in this situation permits male intromission. Thus, superficially benign courtship behaviors may involve cryptic coercion even in species for which intuition dismisses any possibility of forcible insemination.
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Affiliation(s)
- Richard Shine
- School of Biological Sciences A08, University of Sydney, New South Wales, 2006, Australia.
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Abstract
Snakes of both sexes display remarkable flexibility and diversity in their reproductive tactics. Many features of reproduction in female snakes (such as reproductive mode and frequency, seasonality and multiple mating) allow flexible maternal control. For example, females can manipulate not only the genotypes of their offspring (through mate choice or enhanced sperm competition) but also the phenotypes of their offspring (through allocation 'decisions', behavioural and physiological thermoregulation, and nest-site selection). Reliance on stored energy ('capital') to fuel breeding results in low frequencies of female reproduction and, in extreme cases, semelparity. A sophisticated vomeronasal system not only allows male snakes to locate reproductive females by following scent trails, but also facilitates pheromonally mediated mate choice by males. Male-male rivalry takes diverse forms, including female mimicry and mate guarding; combat bouts impose strong selection for large body size in males of some species. Intraspecific (geographical) variation and phenotypic plasticity in a wide array of reproductive traits (offspring size and number; reproductive frequency; incidence of multiple mating; male tactics such as mate guarding and combat; mate choice criteria) provide exceptional opportunities for future studies.
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Affiliation(s)
- Richard Shine
- School of Biological Sciences A08, University of Sydney, Sydney, NSW 2006, Australia.
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Gibbs AG. Lipid melting and cuticular permeability: new insights into an old problem. JOURNAL OF INSECT PHYSIOLOGY 2002; 48:391-400. [PMID: 12770088 DOI: 10.1016/s0022-1910(02)00059-8] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The idea that the physical properties of cuticular lipids affect cuticular permeability goes back over 65 years. This proposal has achieved textbook status, despite controversy and the general lack of direct supporting evidence. Recent work supports the standard model, in which lipid melting results in increased cuticular permeability. Surprisingly, although all species studied to date can synthesize lipids that remain in a solid state at environmental temperatures, partial melting often occurs due to the deposition of lipids with low melting points. This will tend to increase water loss; the benefits may include better dispersal of lipids or other compounds across the cuticle or improved communication via cuticular pheromones. In addition, insects with high melting-point lipids are not necessarily less permeable at low temperatures. One likely reason is variation in lipid properties within the cuticle. Surface lipids differ from one region to another, and biophysical studies of model mixtures suggest the occurrence of phase separation between melted and solid lipid fractions. Lipid phase separation may have important implications for insect water balance and chemical communication.
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Affiliation(s)
- Allen G. Gibbs
- Department of Ecology and Evolutionary Biology & Center for Insect Science, University of Arizona, 1041 E. Lowell St., AZ 85721, Tucson, USA
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Whitfield J. Warm balls wrap she-males. Nature 2001. [DOI: 10.1038/news011115-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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