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Számadó S, Samu F, Takács K. Condition-dependent trade-offs maintain honest signalling. ROYAL SOCIETY OPEN SCIENCE 2022. [PMID: 36249330 DOI: 10.6084/m9.figshare.c.6214769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
How and why animals and humans signal reliably is a key issue in biology and social sciences that needs to be understood to explain the evolution of communication. In situations in which the receiver needs to differentiate between low- and high-quality signallers, once a ruling paradigm, the Handicap Principle has claimed that honest signals have to be costly to produce. Subsequent game theoretical models, however, highlighted that honest signals are not necessarily costly. Honesty is maintained by the potential cost of cheating: by the difference in the marginal benefit to marginal cost for low versus high-quality signallers; i.e. by differential trade-offs. Owing to the difficulties of manipulating signal costs and benefits, there is lack of empirical tests of these predictions. We present the results of a laboratory decision-making experiment with human participants to test the role of equilibrium signal cost and signalling trade-offs for the development of honest communication. We found that the trade-off manipulation had a much higher influence on the reliability of communication than the manipulation of the equilibrium cost of signal. Contrary to the predictions of the Handicap Principle, negative production cost promoted honesty at a very high level in the differential trade-off condition.
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Affiliation(s)
- Szabolcs Számadó
- Department of Sociology and Communication, Budapest University of Technology and Economics, Egry J. u. 1. H-1111, Budapest, Hungary
- CSS-RECENS, CSS-RECENS, Centre for Social Sciences, Tóth Kálmán u. 4, H-1097, Budapest, Hungary
| | - Flóra Samu
- CSS-RECENS, CSS-RECENS, Centre for Social Sciences, Tóth Kálmán u. 4, H-1097, Budapest, Hungary
- Agglomeration and Social Networks Lendület Research Group, Centre for Economic-and Regional Studies, CSS-RECENS, Centre for Social Sciences, Tóth Kálmán u. 4, H-1097, Budapest, Hungary
- Corvinus University of Budapest, Doctoral School of Sociology, Fővám tér. 8, H-1093, Budapest, Hungary
| | - Károly Takács
- The Institute for Analytical Sociology, Linköping University, S-601 74 Norrköping, Sweden
- CSS-RECENS, CSS-RECENS, Centre for Social Sciences, Tóth Kálmán u. 4, H-1097, Budapest, Hungary
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Számadó S, Samu F, Takács K. Condition-dependent trade-offs maintain honest signalling. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220335. [PMID: 36249330 PMCID: PMC9532995 DOI: 10.1098/rsos.220335] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 09/07/2022] [Indexed: 06/16/2023]
Abstract
How and why animals and humans signal reliably is a key issue in biology and social sciences that needs to be understood to explain the evolution of communication. In situations in which the receiver needs to differentiate between low- and high-quality signallers, once a ruling paradigm, the Handicap Principle has claimed that honest signals have to be costly to produce. Subsequent game theoretical models, however, highlighted that honest signals are not necessarily costly. Honesty is maintained by the potential cost of cheating: by the difference in the marginal benefit to marginal cost for low versus high-quality signallers; i.e. by differential trade-offs. Owing to the difficulties of manipulating signal costs and benefits, there is lack of empirical tests of these predictions. We present the results of a laboratory decision-making experiment with human participants to test the role of equilibrium signal cost and signalling trade-offs for the development of honest communication. We found that the trade-off manipulation had a much higher influence on the reliability of communication than the manipulation of the equilibrium cost of signal. Contrary to the predictions of the Handicap Principle, negative production cost promoted honesty at a very high level in the differential trade-off condition.
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Affiliation(s)
- Szabolcs Számadó
- Department of Sociology and Communication, Budapest University of Technology and Economics, Egry J. u. 1. H-1111, Budapest, Hungary
- CSS-RECENS, CSS-RECENS, Centre for Social Sciences, Tóth Kálmán u. 4, H-1097, Budapest, Hungary
| | - Flóra Samu
- CSS-RECENS, CSS-RECENS, Centre for Social Sciences, Tóth Kálmán u. 4, H-1097, Budapest, Hungary
- Agglomeration and Social Networks Lendület Research Group, Centre for Economic-and Regional Studies, CSS-RECENS, Centre for Social Sciences, Tóth Kálmán u. 4, H-1097, Budapest, Hungary
- Corvinus University of Budapest, Doctoral School of Sociology, Fővám tér. 8, H-1093, Budapest, Hungary
| | - Károly Takács
- CSS-RECENS, CSS-RECENS, Centre for Social Sciences, Tóth Kálmán u. 4, H-1097, Budapest, Hungary
- The Institute for Analytical Sociology, Linköping University, S-601 74 Norrköping, Sweden
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The Cocksure Conundrum: How Evolution Created a Gendered Currency of Corporate Overconfidence. ADAPTIVE HUMAN BEHAVIOR AND PHYSIOLOGY 2022. [DOI: 10.1007/s40750-022-00197-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
AbstractBiological differences between men and women mandate that women’s obligatory investment in reproduction is significantly greater than that of men. As a result, women have evolved to be the “choosier” of the two sexes and men have evolved to compete for female choice. To the degree that overconfidence is an effective tool for attracting mates and driving away competitors, greater competition among men suggests that they should express more overconfidence than women. Thus, sexual selection may be the primary reason why overconfidence is typically more pronounced in men than it is in women. Sexual selection may also be a distal, causal factor in what we describe as a cult of overconfidence pervading modern organizations and institutions. Whereas overconfidence was once regulated and constrained by features of ancestral life, levels of social mobility and accountability in contemporary society and modern organizations make it increasingly difficult to keep this gendered bias in check.
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Doherty CT, Laidre ME. Evolutionary loss of threat display in more social species: phylogenetic comparisons, natural interactions in the wild, and experiments with models. BEHAVIOUR 2020. [DOI: 10.1163/1568539x-bja10038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Fitness can be increased dramatically by communication. So why, given the benefits of communication, would displays ever be completely lost evolutionarily? Threat displays, in particular, are relatively cheap to produce and are precursors of attack, so should be especially hard for both senders and receivers to lose completely. Here we explore an evolutionary transition in sociality, testing whether complete evolutionary loss of threat display has occurred in ‘more social’ hermit crab species, which interact more frequently with conspecifics. First, we synthesised literature and observations on the presence versus absence of threat display across hermit crab species, mapping this information onto a phylogenetic tree. We found that all ‘less social’ species — marine and terrestrial — produce threat displays, consistent with threat display being the ancestral state. But ‘more social’ terrestrial species, which are highly derived, do not produce a threat display, suggesting an evolutionary loss. Next, we contrasted natural interactions in the wild within a less social species (Pagurus bernhardus) versus within a more social species (Coenobita compressus), finding that the less social species, despite a lower rate of social encounter, had a higher rate of display per encounter (24%). In contrast, the more social species’ rate of display per encounter was negligible (<1%), effectively indicating a loss in production. Finally, we experimentally reanimated threat display in the more social species, using postured models to test whether receivers retained any responsiveness to threat display. Starkly, receivers were not deterred by threat display, showing equal responsiveness across both threat and non-threat models, regardless of whether the models were stationary or dynamically moving. Our results thus reveal a case of complete collapse of communication involving threat display, implicating the social environment in this loss. In more social species, an extreme dependence on conspecific-derived shells likely drove a ‘desperado effect’, with threat displays being lost because they could not stop others from pursuing these valuable resources.
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Affiliation(s)
- Clare T.M. Doherty
- aDepartment of Biological Sciences, 78 College Street, Dartmouth College, Hanover, NH 03755, USA
- bGraduate Program in Ecology, Evolution, Environment, and Society, Dartmouth College, Hanover, NH 03755, USA
| | - Mark E. Laidre
- aDepartment of Biological Sciences, 78 College Street, Dartmouth College, Hanover, NH 03755, USA
- bGraduate Program in Ecology, Evolution, Environment, and Society, Dartmouth College, Hanover, NH 03755, USA
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Rodríguez RL, Eberhard WG. Why the Static Allometry of Sexually-Selected Traits Is So Variable: The Importance of Function. Integr Comp Biol 2019; 59:1290-1302. [DOI: 10.1093/icb/icz039] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
AbstractSexually-selected traits often show positive static allometry, with large individuals bearing disproportionately large structures. But many other sexually-selected traits show isometry or even negative allometry, with trait size varying relatively little with body size. We recently proposed that the functions of these traits (as aggressive signals, weapons, courtship signals, and contact courtship devices) determine their allometries. Positive allometry is generally favored for aggressive signals because aggressive signals are selected to emphasize body size (and thus fighting prowess). In contrast, the biomechanics of force application in weapons only sometimes select for positive allometry; the content of courtship signals is even less often related to body size; and contact courtship devices are selected to be relatively invariant across body sizes. Here we summarize the arguments in favor of this “functional allometry” hypothesis and expand a comparative test of its predictions. Our results indicate that sexual traits have the allometric slopes predicted by our hypothesis, regardless of which body part bears the structure.
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Affiliation(s)
- Rafael Lucas Rodríguez
- Department of Biological Sciences, Behavioral & Molecular Ecology Group, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - William G Eberhard
- Escuela de Biología, Universidad de Costa Rica, Ciudad Universitaria, San José, Costa Rica; Smithsonian Tropical Research Institute, Panama City, Panama; Museum of Natural Science, Louisiana State University, Baton Rouge, LA, USA
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Pinto NS, Palaoro AV, Peixoto PEC. All by myself? Meta‐analysis of animal contests shows stronger support for self than for mutual assessment models. Biol Rev Camb Philos Soc 2019; 94:1430-1442. [DOI: 10.1111/brv.12509] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Nelson S. Pinto
- Graduate Program in EcologyUniversidade Federal da Bahia Salvador BA 40110‐909 Brazil
| | - Alexandre V. Palaoro
- LAGE do Departamento de EcologiaUniversidade de São Paulo São Paulo SP 05508‐090 Brazil
| | - Paulo E. C. Peixoto
- Instituto de Ciências Biológicas, Departamento de Biologia GeralUniversidade Federal de Minas Gerais Belo Horizonte MG 31270‐901 Brazil
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Eberhard WG, Rodríguez RL, Huber BA, Speck B, Miller H, Buzatto BA, Machado G. Sexual Selection and Static Allometry: The Importance of Function. QUARTERLY REVIEW OF BIOLOGY 2018. [DOI: 10.1086/699410] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Számadó S. When honesty and cheating pay off: the evolution of honest and dishonest equilibria in a conventional signalling game. BMC Evol Biol 2017; 17:270. [PMID: 29281957 PMCID: PMC5745956 DOI: 10.1186/s12862-017-1112-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 12/08/2017] [Indexed: 11/27/2022] Open
Abstract
Background The reliability of signals is a key issue in the study of animal communication. Both empirical work and theoretical models show that communication need not be entirely honest, and thus signals can be deceitful. Aggressive communication appears to be a prime candidate for such deceitful communication, because bluffing has been described in several species. Bluffing in these situations are supposed to be maintained by frequency dependent selection where the fitness of a given type depends on the frequencies of the other types in the population. Previous efforts to model such a scenario through individual based simulations have yielded conflicting results. Studies have either found a rich set of polymorphic strategies including the traditional cheating scenario or found none. Thus, the modelling assumptions responsible for these diverging conclusions remain unclear. Results In this study, I investigate the effects of four modelling assumptions: the role of an extended strategy set, the initial population composition (seeding), the differences in pay-offs and finally different parameter spaces. I investigate the effects of these factors on the evolvability of both honest and mixed cheating strategies. I show that both honest and cheating equilibria readily evolve and that the investigated parameter range and the seeding of the starting populations have the greatest influence on the outcome. Conclusions Both honest signalling and polymorphic cheating equilibria are more likely to evolve from a narrow strategy set than from a random mixture of strategies. A large potential strategy set is not a setback for the evolution of communication -honest or cheating- as long as the initial population is seeded with only a few strategies. In addition, different sections of the parameter space show consistently different behaviour. Thus, frequency dependent selection has the potential to explain various empirical observations that show consistent differences in aggressive behaviour. Electronic supplementary material The online version of this article (10.1186/s12862-017-1112-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Szabolcs Számadó
- MTA TK "Lendület" Research Center for Educational and Network Studies (RECENS), Tóth Kálmán u. 4, Budapest, H-1097, Hungary.
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Stritih N, Žunič Kosi A. Olfactory signaling of aggressive intent in male-male contests of cave crickets (Troglophilus neglectus; Orthoptera: Rhaphidophoridae). PLoS One 2017; 12:e0187512. [PMID: 29112984 PMCID: PMC5675388 DOI: 10.1371/journal.pone.0187512] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/22/2017] [Indexed: 11/19/2022] Open
Abstract
In animal contests, communicating aggressive motivation is most often mediated by visual or acoustic signals, while chemical signals are not expected to serve such a function since they are less able to be modulated by the sender during the changing behavioral context. We describe a rare example of ephemeral olfactory signals in terrestrial animals, signals that are emitted via protrusive scent glands in male cave crickets Troglophilus neglectus (Orthoptera, Rhaphidophoridae) to reflect the state of the signaler's aggression. We correlate the intensity of behaviorally expressed aggression of the individuals in dyadic contests with the frequency and extent of their gland tissue protrusion, the latter serving as an indication of the amount of released odor. We detected large amounts of odor release during brief gland protrusions, and the absence of its release during gland retraction. Males protruded the glands during and after encountering a rival, with the degree of protrusion increasing with the intensity of the signalers' aggression. During the encounters, the degree of gland protrusion increased most strongly with the occurrence of the elevated body posture, directly preceding the attack. This degree was significantly higher in encounter winners than in losers displaying such posture, suggesting the highly important role of the released odor for contest resolution. After the encounters, glands were protruded almost exclusively by winners, apparently announcing victory. We tested for the function of the olfactory signals also directly, by preventing gland tissue protrusion in symmetric and asymmetric treatments of the contestants. Treating only the dominant individuals decreased the percentage of encounters they won by over 60%, while treating both contestants elicited a significant increase in the frequency and duration of fights. During contests, the olfactory signals of T. neglectus apparently function as a highly effective threat, which prevents maximal contest escalation and decreases the conflict-related costs.
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Affiliation(s)
- Nataša Stritih
- National Institute of Biology, Department of Organisms and Ecosystems Research, Ljubljana, Slovenia
- * E-mail:
| | - Alenka Žunič Kosi
- National Institute of Biology, Department of Organisms and Ecosystems Research, Ljubljana, Slovenia
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Guimarães M, MunguÍa-Steyer R, Doherty PF, Sawaya RJ. No survival costs for sexually selected traits in a polygynous non-territorial lizard. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx097] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Ręk P. Do aggressive signals evolve towards higher reliability or lower costs of assessment? J Evol Biol 2014; 27:2605-13. [PMID: 25290527 DOI: 10.1111/jeb.12512] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/12/2014] [Indexed: 11/28/2022]
Abstract
It has been suggested that the evolution of signals must be a wasteful process for the signaller, aimed at the maximization of signal honesty. However, the reliability of communication depends not only on the costs paid by signallers but also on the costs paid by receivers during assessment, and less attention has been given to the interaction between these two types of costs during the evolution of signalling systems. A signaller and receiver may accept some level of signal dishonesty by choosing signals that are cheaper in terms of assessment but that are stabilized with less reliable mechanisms. I studied the potential trade-off between signal reliability and the costs of signal assessment in the corncrake (Crex crex). I found that the birds prefer signals that are less costly regarding assessment rather than more reliable. Despite the fact that the fundamental frequency of calls was a strong predictor of male size, it was ignored by receivers unless they could directly compare signal variants. My data revealed a response advantage of costly signals when comparison between calls differing with fundamental frequencies is fast and straightforward, whereas cheap signalling is preferred in natural conditions. These data might improve our understanding of the influence of receivers on signal design because they support the hypothesis that fully honest signalling systems may be prone to dishonesty based on the effects of receiver costs and be replaced by signals that are cheaper in production and reception but more susceptible to cheating.
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Affiliation(s)
- P Ręk
- Department of Behavioural Ecology, Faculty of Biology, Institute of Environmental Biology, Adam Mickiewicz University, Poznań, Poland; Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT, Australia
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Hackett S, Schaefer HM, Ruxton GD. Linking signal fidelity and the efficiency costs of communication. J Evol Biol 2014; 27:1797-810. [DOI: 10.1111/jeb.12427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/06/2014] [Accepted: 05/07/2014] [Indexed: 11/27/2022]
Affiliation(s)
- S. Hackett
- Department of Zoology; University of Oxford; Oxford UK
| | - H. M. Schaefer
- Faculty of Biology I; University of Freiburg; Freiburg Germany
| | - G. D. Ruxton
- School of Biology; University of St Andrews; St Andrews UK
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Soft calls and broadcast calls in the corncrake as adaptations to short and long range communication. Behav Processes 2013; 99:121-9. [DOI: 10.1016/j.beproc.2013.07.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 06/14/2013] [Accepted: 07/06/2013] [Indexed: 11/24/2022]
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Assessment of self, opponent and resource during male–male contests in the sierra dome spider, Neriene litigiosa: Linyphiidae. Anim Behav 2010. [DOI: 10.1016/j.anbehav.2010.07.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Ręk P, Osiejuk TS. Sophistication and simplicity: conventional communication in a rudimentary system. Behav Ecol 2010. [DOI: 10.1093/beheco/arq143] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Moore JC, Obbard DJ, Reuter C, West SA, Cook JM. Male morphology and dishonest signalling in a fig wasp. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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21
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Számadó S. How threat displays work: species-specific fighting techniques, weaponry and proximity risk. Anim Behav 2008. [DOI: 10.1016/j.anbehav.2008.07.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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ANDERSON ROGERA, MCBRAYER LANCED, HERREL ANTHONY. Bite force in vertebrates: opportunities and caveats for use of a nonpareil whole-animal performance measure. Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2007.00905.x] [Citation(s) in RCA: 150] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Early hominins, australopiths, were similar to most large primates in having relatively short hindlimbs for their body size. The short legs of large primates are thought to represent specialization for vertical climbing and quadrupedal stability on branches. Although this may be true, there are reasons to suspect that the evolution of short legs may also represent specialization for physical aggression. Fighting in apes is a behavior in which short legs are expected to improve performance by lowering the center of mass during bipedal stance and by increasing the leverage through which muscle forces can be applied to the ground. Among anthropoid primates, body size sexual dimorphism (SSD) and canine height sexual dimorphism (CSD) are strongly correlated with levels of male-male competition, allowing SSD and CSD to be used as indices of male-male aggression. Here I show that the evolution of hindlimb length in apes is inversely correlated with the evolution of SSD (R(2)= 0.683, P-value = 0.006) and the evolution of CSD (R(2)= 0.630, P-value = 0.013). In contrast, a significant correlation was not observed for the relationship between the evolution of hindlimb and forelimb lengths. These observations are consistent with the suggestion that selection for fighting performance has maintained relatively short hindlimbs in species of Hominoidea with high levels of male-male competition. Although australopiths were highly derived for striding bipedalism when traveling on the ground, they retained short legs compared to those of Homo for over two million years, approximately 100,000 generations. Their short legs may be indicative of persistent selection for high levels of aggression.
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Affiliation(s)
- David R Carrier
- Department of Biology, 201 South Biology Building, University of Utah, Salt Lake City, Utah 84112, USA.
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Lappin AK, Brandt Y, Husak JF, Macedonia JM, Kemp DJ. Gaping displays reveal and amplify a mechanically based index of weapon performance. Am Nat 2006; 168:100-13. [PMID: 16874617 DOI: 10.1086/505161] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Accepted: 04/12/2006] [Indexed: 11/04/2022]
Abstract
Physical prowess, a key determinant of fight outcomes, is contingent on whole-organism performance traits. The advertisement of performance, via display, is poorly understood because it is unclear how information about performance is encoded into display characteristics. Previous studies have shown that weapon performance (i.e., bite force) predicts dominance and reproductive success in male lizards. We tested the hypothesis that gaping displays by adult male collared lizards (Crotaphytus) can provide an index of weapon performance by exposing the major jaw-adductor muscle complex and that white patches at the mouth corners amplify this index. For territorial adult males, the breadth of the muscle complex, which is not correlated with body size, was a strong predictor of bite force. For nonterritorial yearling males and females, however, measures of body and head size predicted bite force. The patches are highly conspicuous, exhibit UV-reflecting properties within the visual range of lizards, and provide size-independent information about bite force only in adult males. We conclude that exposure of the muscle complex during gaping displays can provide rival males with a reliable, body-size independent, biomechanically based index of weapon performance, an index that the mouth-corner patches amplify. Indexes that transmit information through mechanistic links to performance are expected to be widespread among animals.
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Affiliation(s)
- A Kristopher Lappin
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA.
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Castro N, Ros AF, Becker K, Oliveira RF. Metabolic costs of aggressive behaviour in the Siamese fighting fish,Betta splendens. Aggress Behav 2006. [DOI: 10.1002/ab.20147] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Harper DGC. Maynard Smith: amplifying the reasons for signal reliability. J Theor Biol 2005; 239:203-9. [PMID: 16225891 DOI: 10.1016/j.jtbi.2005.08.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 07/25/2005] [Accepted: 07/26/2005] [Indexed: 11/25/2022]
Abstract
One of the many questions to which John Maynard Smith contributed was that of why most animal signals are reliable. He initially rejected the "handicap" argument but gradually accepted it, a process I briefly describe. This episode illustrated his preference for mathematical models over verbal ones, and the generosity with which he could change his mind. Even after accepting that some signals are reliable because of their strategic costs, he argued for a pluralistic approach to signal reliability. Signal complexity was a developing interest when he died. Signals usually involve several components, some of which appear to amplify other signal components. The terms "amplifier" and "index" require more thought to reduce the scope for semantic confusion. I conclude by describing Maynard Smith's fascination with peacocks Pavo cristatus.
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Affiliation(s)
- D G C Harper
- Centre for the Study of Evolution, School of Biological Sciences, University of Sussex, Falmer, Brighton & Hove BN1 9QG, UK.
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