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Publications (4)13.8 Total impact

  • Candice L. Bywater, Robbie S. Wilson
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    ABSTRACT: 1. Contests between conspecific males are an important method of establishing mating rights or territories, yet the potential costs of injuries are high. To reduce potential risks, males can use signals to convey information about their underlying strength to competitors, and although individuals could signal deceptively to gain an advantage, most signals seem to be reliable. 2. Theory suggests that signal reliability is maintained because individuals that signal unreliably may be punished (i.e. receiver-imposed costs). Manipulative studies support this idea, showing that low-quality individuals that are given high-quality signals bear substantial costs. 3. Here, we explore the importance of receiver-imposed costs in natural, un-manipulated populations. Specifically, we show how the likelihood of being exposed (i.e. potential receiver density) and the potential severity of punishment (i.e. average receiver size) affect the predominance of unreliable signalling among populations. 4. Male fiddler crabs, Uca vomeris, use their enlarged claws as signals and weapons in combat, and the relationship between claw size (signal) and strength (quality) determines whether or not a male is a reliable signaller. We predicted that the prevalence of unreliable signalling among individual males would increase in populations where the receiver-imposed costs of deception were low. That is, males should produce unreliable (large but weak) claws. 5. We show that individual crabs produce more reliable signals of strength in populations with a high biomass, where there are both higher densities and larger average body sizes of potential receivers. Our study provides evidence that receiver-imposed costs can maintain signal reliability in natural un-manipulated populations and supports contemporary models of aggressive signalling.
    Functional Ecology 08/2012; 26(4):804-811. · 4.86 Impact Factor
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    ABSTRACT: Deception remains a hotly debated topic in evolutionary and behavioural research. Our understanding of what impedes or facilitates the use and detection of deceptive signals in humans is still largely limited to studies of verbal deception under laboratory conditions. Recent theoretical models of non-human behaviour have suggested that the potential outcome for deceivers and the ability of receivers to discriminate signals can effectively maintain their honesty. In this paper, we empirically test these predictions in a real-world case of human deception, simulation in soccer. In support of theoretical predictions in signalling theory, we show that cost-free deceit by soccer players decreases as the potential outcome for the signaller becomes more costly. We further show that the ability of receivers (referees) to detect deceptive signals may limit the prevalence of deception by soccer players. Our study provides empirical support to recent theoretical models in signalling theory, and identifies conditions that may facilitate human deception and hinder its detection.
    PLoS ONE 01/2011; 6(10):e26017. · 3.53 Impact Factor
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    ABSTRACT: Unreliable signals of weapon strength are considered to be problematic for signalling theory and reliable signals are predicted to be the dominant form of signalling among conspecifics in nature. Previous studies have shown that males of the Australian freshwater crayfish (Cherax dispar) routinely use unreliable signals of strength whereas females use reliable signals of weapon strength. In this study, we examined the performance benefits of increased weapon (chela) size for both males and females of C. dispar. In addition, we investigated the possibility of functional trade-offs in weapon size by assessing the relationship between chela size and maximum escape swimming performance. We found males possessed larger and stronger chelae than females and the variance in chela force was greater for males than females. By contrast, females possessed greater absolute and body length-specific escape swimming speeds than males. Swimming speed was also negatively correlated with chela size for males but not females, suggesting that a functional trade-off exists for males only. Decreases in swimming speed with increases in weapon size suggest there could be important fitness costs associated with larger chelae. Larger weaponry of males may then act as a handicap ensuring large chelae are reliable signals of quality.
    Journal of Experimental Biology 04/2009; 212(Pt 6):853-8. · 3.24 Impact Factor
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    ABSTRACT: Cherax dispar. Crayfish routinely use their enlarged front claws (chelae) for both intimidation and fighting, making them an ideal system to examine the honesty of signals of fighting capacity. We evaluated five competing models relating morphological and physiological traits (body length, body condition, claw size, and claw strength) to dominance during paired competitive bouts. In an honest signaling system, claw size and strength will be good predictors of dominance during competitive interactions. We found females that possessed large chelae were more likely to possess stronger chelae and those individuals with stronger chelae were more likely to win competitive bouts, thus supporting current theory. In contrast, we found chelae strength of individual male C. dispar had no bearing on their dominance ability, indicating that displays of claw size were dishonest signals and the enlarged claws of males function more for intimidation than actual strength. Given the extent of bluffing among male C. dispar, it appears current theory underestimates the potential importance of dishonest signals in intraspecific animal communication.
    Comparative Biochemistry and Physiology - Part A Molecular & Integrative Physiology 04/2007; · 2.17 Impact Factor