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Keller PE, Lee J, König R, Novembre G. Sex-related communicative functions of voice spectral energy in human chorusing. Biol Lett 2023; 19:20230326. [PMID: 37935372 PMCID: PMC10645082 DOI: 10.1098/rsbl.2023.0326] [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: 07/12/2023] [Accepted: 10/16/2023] [Indexed: 11/09/2023] Open
Abstract
Music is a human communicative art whose evolutionary origins may lie in capacities that support cooperation and/or competition. A mixed account favouring simultaneous cooperation and competition draws on analogous interactive displays produced by collectively signalling non-human animals (e.g. crickets and frogs). In these displays, rhythmically coordinated calls serve as a beacon whereby groups of males 'cooperatively' attract potential female mates, while the likelihood of each male competitively attracting an actual mate depends on the precedence of his signal. Human behaviour consistent with the mixed account was previously observed in a renowned boys choir, where the basses-the oldest boys with the deepest voices-boosted their acoustic prominence by increasing energy in a high-frequency band of the vocal spectrum when girls were in an otherwise male audience. The current study tested female and male sensitivity and preferences for this subtle vocal modulation in online listening tasks. Results indicate that while female and male listeners are similarly sensitive to enhanced high-spectral energy elicited by the presence of girls in the audience, only female listeners exhibit a reliable preference for it. Findings suggest that human chorusing is a flexible form of social communicative behaviour that allows simultaneous group cohesion and sexually motivated competition.
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Affiliation(s)
- Peter E. Keller
- Center for Music in the Brain, Department of Clinical Medicine, Aarhus University, Aarhus 8000, Denmark
- The MARCS Institute for Brain, Behaviour and Development, Western Sydney University, Penrith South, Australia
| | - Jennifer Lee
- Queensland Aphasia Research Centre, University of Queensland, Brisbane, Queensland, Australia
| | | | - Giacomo Novembre
- Neuroscience of Perception and Action Lab, Italian Institute of Technology, Rome, Italy
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2
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Perez DM, Klunk CL, Araujo SBL. Imperfect synchrony in animal displays: why does it occur and what is the true role of leadership? Philos Trans R Soc Lond B Biol Sci 2021; 376:20200339. [PMID: 34420387 PMCID: PMC8384059 DOI: 10.1098/rstb.2020.0339] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2021] [Indexed: 11/12/2022] Open
Abstract
Synchrony can be defined as the precise coordination between independent individuals, and this behaviour is more enigmatic when it is imperfect. The traditional theoretical explanation for imperfect synchronous courtship is that it arises as a by-product of the competition between males to broadcast leading signals to attract female attention. This competition is considered an evolutionary stable strategy maintained through sexual selection. However, previous studies have revealed that leading signals are not honest indicators of male quality. We studied imperfect courtship synchrony in fiddler crabs to mainly test whether (i) signal leadership and rate are defined by male quality and (ii) signal leadership generates synchrony. Fiddler crab males wave their enlarged claws during courtship, and females prefer leading males-displaying ahead of their neighbour(s). We filmed groups of waving males in the field to detect how often individuals were leaders and if they engaged in synchrony. Overall, we found that courtship effort is not directly related to male size, a general proxy for quality. Contrary to the long-standing assumption, we also revealed that leadership is not directly related to group synchrony, but faster wave rate correlates with both leadership and synchrony. This article is part of the theme issue 'Synchrony and rhythm interaction: from the brain to behavioural ecology'.
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Affiliation(s)
- Daniela M. Perez
- Graduate Program in Ecology and Conservation, Universidade Federal do Paraná, Curitiba, Parana 81531-990, Brazil
| | - Cristian L. Klunk
- Graduate Program in Ecology and Conservation, Universidade Federal do Paraná, Curitiba, Parana 81531-990, Brazil
| | - Sabrina B. L. Araujo
- Department of Physics, Laboratory of Biological Interactions, Universidade Federal do Paraná, Curitiba, Parana 81531-990, Brazil
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3
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Greenfield MD, Aihara I, Amichay G, Anichini M, Nityananda V. Rhythm interaction in animal groups: selective attention in communication networks. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200338. [PMID: 34420386 DOI: 10.1098/rstb.2020.0338] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Animals communicating interactively with conspecifics often time their broadcasts to avoid overlapping interference, to emit leading, as opposed to following, signals or to synchronize their signalling rhythms. Each of these adjustments becomes more difficult as the number of interactants increases beyond a pair. Among acoustic species, insects and anurans generally deal with the problem of group signalling by means of 'selective attention' in which they focus on several close or conspicuous neighbours and ignore the rest. In these animals, where signalling and receiving are often dictated by sex, the process of selective attention in signallers may have a parallel counterpart in receivers, which also focus on close neighbours. In birds and mammals, local groups tend to be extended families or clans, and group signalling may entail complex timing mechanisms that allow for attention to all individuals. In general, the mechanisms that allow animals to communicate in groups appear to be fully interwoven with the basic process of rhythmic signalling. This article is part of the theme issue 'Synchrony and rhythm interaction: from the brain to behavioural ecology'.
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Affiliation(s)
- Michael D Greenfield
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA.,Equipe Neuro-Ethologie Sensorielle, ENES/Neuro-PSI, CNRS UMR 9197, University of Lyon/Saint-Etienne, 42023 Saint Etienne, France
| | - Ikkyu Aihara
- Faculty of Engineering, Information and Systems, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Guy Amichay
- Department of Collective Behaviour, Max Planck Institute of Animal Behavior, 78467 Konstanz, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78464 Konstanz, Germany.,Department of Biology, University of Konstanz, 78464 Konstanz, Germany
| | - Marianna Anichini
- Hanse-Wissenschaftskolleg Institute for Advanced Study, 'Brain' Research Area, 27753 Delmenhorst, Germany.,Animal Physiology and Behavior Group, Department of Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, 26129 Oldenburg, Germany
| | - Vivek Nityananda
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle Upon Tyne NE2 4HH, UK
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4
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Harrison LM, Melo GC, Perez DM, Backwell PRY. Why signal if you are not attractive? Courtship synchrony in a fiddler crab. Behav Ecol 2021. [DOI: 10.1093/beheco/arab088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Synchronized male courtship signals are puzzling because males generally compete with each other for females. Male Austruca mjoebergi fiddler crabs wave in synchrony to attract females, but, all else being equal, females have a strong preference for “leader” males that can produce waves before other males (“followers”). So why do followers participate in synchrony? Here, we experimentally investigate three explanations for why followers might wave in synchrony: 1) followers obtain a small proportion of matings, 2) followers are more likely than a leader to attract females if they are positioned closer to her than is the leader, and 3) synchrony functions as a long-distance visual signal that attracts females so there is a net benefit to synchrony for all males. Using robotic male crabs, we found that females show a strong preference for leading males, but followers obtain a “better-than-nothing” proportion of mates. We also showed that closer proximity of a follower to the female did not affect her preference for leaders, although being a leader increased a male’s success when he was further from the female than were rival males. Finally, females were more likely to approach a distant group if there was a leader present, suggesting that followers do benefit from participating in synchrony.
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Affiliation(s)
- Lauren M Harrison
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
| | - Gabriela C Melo
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, VIC, 3800, Australia
| | - Daniela M Perez
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
- Graduate Program in Ecology and Conservation, Universidade Federal do Paraná, Caixa Postal 19031, Curitiba, PR, 81531-990, Brazil
| | - Patricia R Y Backwell
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
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5
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Rebar D, Barbosa F, Greenfield MD. Female reproductive plasticity to the social environment and its impact on male reproductive success. Behav Ecol Sociobiol 2019. [DOI: 10.1007/s00265-019-2661-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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6
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Esquer-Garrigos Y, Streiff R, Party V, Nidelet S, Navascués M, Greenfield MD. Pleistocene origins of chorusing diversity in Mediterranean bush-cricket populations ( Ephippiger diurnus). Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/bly195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Yareli Esquer-Garrigos
- CBGP, INRA, CIRAD, IRD, Université de Montpellier, Montpellier, France
- DGIMI, INRA, Université de Montpellier, Montpellier, France
- Université de Tours, Tours, France
| | - Réjane Streiff
- CBGP, INRA, CIRAD, IRD, Université de Montpellier, Montpellier, France
- DGIMI, INRA, Université de Montpellier, Montpellier, France
| | | | - Sabine Nidelet
- CBGP, INRA, CIRAD, IRD, Université de Montpellier, Montpellier, France
| | | | - Michael D Greenfield
- Université de Tours, Tours, France
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA
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7
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Backwell PRY. Synchronous waving in fiddler crabs: a review. Curr Zool 2018; 65:83-88. [PMID: 30697243 PMCID: PMC6347057 DOI: 10.1093/cz/zoy053] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 06/28/2018] [Indexed: 11/15/2022] Open
Abstract
Many animals that use acoustic communication synchronize their mate attraction signals: individuals precisely time their calls to overlap those of their neighbors. In contrast, synchrony in the mate attraction displays of species with visual/motion-based signals is rare. It has only been documented in five species of fiddler crabs. In all of them, small groups of males wave their single large claw in close synchrony. Here, I review what we know about synchrony in fiddler crabs, comparing the five species with each other to determine whether similar mechanisms and functions are common to all. I also propose future research questions that, if answered, would shed light on synchronous behavior in both visual and acoustic signallers.
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8
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Barbosa F, Rebar D, Greenfield MD. When do trade-offs occur? The roles of energy constraints and trait flexibility in bushcricket populations. J Evol Biol 2017; 31:287-301. [PMID: 29215173 DOI: 10.1111/jeb.13221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 11/28/2017] [Indexed: 11/28/2022]
Abstract
In many animal species, the expression of sexually selected traits is negatively correlated with traits associated with survival such as immune function, a relationship termed a 'trade-off'. But an alternative in which sexually selected traits are positively correlated with survival traits is also widespread. We propose that the nature of intertrait relationships is largely determined by overall energy expenditure, energy availability and trait flexibility, with trade-offs expected when individuals are subject to energy constraints. We tested this hypothesis in Ephippiger diurnus, a European bushcricket in which males are distinguished by two prominent sexually selected traits, acoustic calls and a large spermatophore transferred to the female at mating, and where immune function may be critical in survival. Ephippiger diurnus are distributed as small, isolated populations that are differentiated genetically and behaviourally. We analysed songs, spermatophores and the immune function in male individuals from eight populations spanning a range of song types. As predicted, we only found trade-offs in those populations that expended more energy on song and were less flexible in their ability to adjust that expenditure. Ultimately, energy constraints and resulting trade-offs may limit the evolution of song exaggeration in E. diurnus populations broadcasting long calls comprised of multiple 'syllables'.
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Affiliation(s)
- F Barbosa
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), Faculté des Sciences et Techniques, UMR 7261, Tours, France.,Department of Biology, Lake Forest College, Lake Forest, IL, USA
| | - D Rebar
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), Faculté des Sciences et Techniques, UMR 7261, Tours, France.,Department of Zoology, University of Cambridge, Cambridge, UK
| | - M D Greenfield
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), Faculté des Sciences et Techniques, UMR 7261, Tours, France
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9
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Murphy MA, Gerhardt HC, Schul J. Leader preference in Neoconocephalus ensiger katydids: a female preference for a nonheritable male trait. J Evol Biol 2017; 30:2222-2229. [PMID: 28976614 DOI: 10.1111/jeb.13188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/24/2017] [Accepted: 09/28/2017] [Indexed: 11/28/2022]
Abstract
Female preferences for males producing their calls just ahead of their neighbours, leader preferences, are common in acoustically communicating insects and anurans. While these preferences have been well studied, their evolutionary origins remain unclear. We tested whether females gain a fitness benefit by mating with leading males in Neoconocephalus ensiger katydids. We mated leading and following males with random females and measured the number and quality of F1 , the number of F2 and the heritability of the preferred male trait. We found that females mating with leaders and followers did not differ in the number of F1 or F2 offspring. Females mating with leading males had offspring that were in better condition than those mating with following males suggesting a benefit in the form of higher quality offspring. We found no evidence that the male trait, the production of leading calls, was heritable. This suggests that there is no genetic correlate for the production of leading calls and that the fitness benefit gained by females must be a direct benefit, potentially mediated by seminal proteins. The presence of benefits indicates that leader preference is adaptive in N. ensiger, which may explain the evolutionary origin of leader preference; further tests are required to determine whether fitness benefits can explain the phylogenetic distribution of leader preference in Neoconocephalus. The absence of heritability will prevent leader preference from becoming coupled with or exaggerating the male trait and prevent females from gaining a 'sexy-sons' benefit, weakening the overall selection for leader preference.
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Affiliation(s)
- M A Murphy
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA.,Biological Sciences, Salisbury University, Salisbury, MD, USA
| | - H C Gerhardt
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA
| | - J Schul
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA
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10
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Greenfield MD, Marin-Cudraz T, Party V. Evolution of synchronies in insect choruses. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx096] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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11
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Phylogeographic structure without pre-mating barriers: Do habitat fragmentation and low mobility preserve song and chorus diversity in a European bushcricket? Evol Ecol 2017. [DOI: 10.1007/s10682-017-9914-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Rebar D, Greenfield MD. When do acoustic cues matter? Perceived competition and reproductive plasticity over lifespan in a bushcricket. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Barbosa F, Rebar D, Greenfield MD. Female preference functions drive interpopulation divergence in male signalling: call diversity in the bushcricket Ephippiger diurnus. J Evol Biol 2016; 29:2219-2228. [PMID: 27471011 DOI: 10.1111/jeb.12940] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 06/21/2016] [Accepted: 07/01/2016] [Indexed: 11/30/2022]
Abstract
Female preferences play a major role in the elaboration and diversification of male traits: as a selective pressure on males, variation in female preferences can generate population divergence and ultimately, speciation. We studied how interpopulation differences in the shape of female mate preference functions may have shaped male advertisement signals in the bushcricket Ephippiger diurnus. This species is distributed as geographically isolated populations with striking interpopulation variation in male acoustic signals, most notably in the number of syllables per call. Here, we asked whether differences in the shape of preference functions exist among populations and whether those differences may have driven male signal evolution resulting in the observed differences in syllable numbers. Our results reveal fundamental differences in female preferences among populations, with differences in the overall preference function shape corresponding to differences in male signals. These differences in female preferences best explain the major differences in male signals among populations. The interpopulation variation in signals and preferences potentially reflects the evolutionary history of the species and may contribute to further divergence among populations and subsequent speciation.
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Affiliation(s)
- F Barbosa
- UMR 7261, Faculté des Sciences et Techniques, Institut de Recherche sur la Biologie de l'Insecte (IRBI), Tours, France.
| | - D Rebar
- UMR 7261, Faculté des Sciences et Techniques, Institut de Recherche sur la Biologie de l'Insecte (IRBI), Tours, France.,Department of Zoology, University of Cambridge, Cambridge, UK
| | - M D Greenfield
- UMR 7261, Faculté des Sciences et Techniques, Institut de Recherche sur la Biologie de l'Insecte (IRBI), Tours, France
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14
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Greenfield MD, Esquer-Garrigos Y, Streiff R, Party V. Animal choruses emerge from receiver psychology. Sci Rep 2016; 6:34369. [PMID: 27670673 PMCID: PMC5037466 DOI: 10.1038/srep34369] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 09/13/2016] [Indexed: 11/23/2022] Open
Abstract
Synchrony and alternation in large animal choruses are often viewed as adaptations by which cooperating males increase their attractiveness to females or evade predators. Alternatively, these seemingly composed productions may simply emerge by default from the receiver psychology of mate choice. This second, emergent property hypothesis has been inferred from findings that females in various acoustic species ignore male calls that follow a neighbor's by a brief interval, that males often adjust the timing of their call rhythm and reduce the incidence of ineffective, following calls, and from simulations modeling the collective outcome of male adjustments. However, the purported connection between male song timing and female preference has never been tested experimentally, and the emergent property hypothesis has remained speculative. Studying a distinctive katydid species genetically structured as isolated populations, we conducted a comparative phylogenetic analysis of the correlation between male call timing and female preference. We report that across 17 sampled populations male adjustments match the interval over which females prefer leading calls; moreover, this correlation holds after correction for phylogenetic signal. Our study is the first demonstration that male adjustments coevolved with female preferences and thereby confirms the critical link in the emergent property model of chorus evolution.
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Affiliation(s)
- Michael D. Greenfield
- Institut de recherche sur la biologie de l’insecte (IRBI), CNRS UMR 7261, Parc de Grandmont, Université François Rabelais de Tours, 37200 Tours, France
| | - Yareli Esquer-Garrigos
- INRA, UMR 1062 CBGP, Campus International de Baillarguet, F-34988 Montferrier-sur-Lez, France
- INRA, UMR 1333 DGIMI, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier cedex 5, France
| | - Réjane Streiff
- INRA, UMR 1062 CBGP, Campus International de Baillarguet, F-34988 Montferrier-sur-Lez, France
- INRA, UMR 1333 DGIMI, Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier cedex 5, France
| | - Virginie Party
- Institut de recherche sur la biologie de l’insecte (IRBI), CNRS UMR 7261, Parc de Grandmont, Université François Rabelais de Tours, 37200 Tours, France
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15
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Finely tuned choruses: bush crickets adjust attention to neighboring singers in relation to the acoustic environment they create. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2166-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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Hartbauer M, Römer H. Rhythm Generation and Rhythm Perception in Insects: The Evolution of Synchronous Choruses. Front Neurosci 2016; 10:223. [PMID: 27303257 PMCID: PMC4885851 DOI: 10.3389/fnins.2016.00223] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/06/2016] [Indexed: 11/15/2022] Open
Abstract
Insect sounds dominate the acoustic environment in many natural habitats such as rainforests or meadows on a warm summer day. Among acoustic insects, usually males are the calling sex; they generate signals that transmit information about the species-identity, sex, location, or even sender quality to conspecific receivers. Males of some insect species generate signals at distinct time intervals, and other males adjust their own rhythm relative to that of their conspecific neighbors, which leads to fascinating acoustic group displays. Although signal timing in a chorus can have important consequences for the calling energetics, reproductive success and predation risk of individuals, still little is known about the selective forces that favor the evolution of insect choruses. Here, we review recent advances in our understanding of the neuronal network responsible for acoustic pattern generation of a signaler, and pattern recognition in receivers. We also describe different proximate mechanisms that facilitate the synchronous generation of signals in a chorus and provide examples of suggested hypotheses to explain the evolution of chorus synchrony in insects. Some hypotheses are related to sexual selection and inter-male cooperation or competition, whereas others refer to the selection pressure exerted by natural predators. In this article, we summarize the results of studies that address chorus synchrony in the tropical katydid Mecopoda elongata, where some males persistently signal as followers although this reduces their mating success.
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Affiliation(s)
- Manfred Hartbauer
- Behavioural Ecology and Neurobiology, Institute of Zoology, University of GrazGraz, Austria
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Keeping up with the neighbor: a novel mechanism of call synchrony in Neoconocephalus ensiger katydids. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2016; 202:225-34. [PMID: 26809565 DOI: 10.1007/s00359-016-1068-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/09/2016] [Accepted: 01/11/2016] [Indexed: 10/22/2022]
Abstract
During solo calling, pulse periods gradually changed by up to 15% over several minutes. Pairs of calling males synchronized their pulses. The pulse rate (10-14 Hz) was considerably faster than the rate of synchronized signal units in other insects (0.5-3 Hz). Within each pulse cycle, males made only small adjustments to their pulse period, leading to regular switches of leader and follower roles. Large-scale timing adjustments only occurred in response to large delays. Stimulation with single pulses had no predictable effect on the timing of the male's next pulse, resulting in a flat phase response curve. When entrained to a stimulus with a faster pulse period, males briefly interrupted calling; they resumed calling largely synchronized with the stimulus. Throughout the stimulus, males made gradual changes to their pulse period, similar to those during pair calling. After the stimulus ended, pulse periods increased over several minutes, but did not return to their pre-stimulus values. Thus social context and intrinsic state of the males influenced pulse period in Neoconocephalus ensiger. These results indicate that N. ensiger males synchronize calls by adjusting their intrinsic pulse period, instead of adjusting the timing of individual pulses, as described in other synchronizing insects.
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