School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia.
J Exp Biol. 2011 Oct 1;214(Pt 19):3294-9. doi: 10.1242/jeb.056754.
The maintenance of unreliable signals within animal populations remains a highly controversial subject in studies of animal communication. Crustaceans are an ideal group for studying unreliable signals of strength because their chela muscles are cryptically concealed beneath an exoskeleton, making it difficult for competitors to visually assess an opponent's strength. In this study, we examined the importance of social avenues for mediating the possible advantages gained by unreliable signals of strength in crustaceans. To do this, we investigated the factors that determine social dominance and the relative importance of signalling and fighting during aggressive encounters in male and female freshwater crayfish, Cherax destructor. Like other species of crayfish, we expected substantial variation in weapon force for a given weapon size, making the assessment of actual fighting ability of an opponent difficult from signalling alone. In addition, we expected fighting would be used to ensure that individuals that are weak for their signal (i.e. chela) size would not achieve higher than expected dominance. For both male and female C. destructor, we found large variation in the actual force of their chela for any given weapon size, indicating that it is difficult for competitors to accurately assess an opponent's force on signal size alone. For males, these unreliable signals of strength were controlled socially through increased levels of fighting and a decreased reliance on signalling, thus directly limiting the benefits accrued to individuals employing high-quality signals (large chelae) with only low resource holding potential. However, in contrast to our predictions, we found that females primarily relied on signalling to settle disputes, resulting in unreliable signals of strength being routinely used to establish dominance. The reliance by females on unreliable signals to determine dominance highlights our poor current understanding of the prevalence and distribution of dishonesty in animal communication.
在动物通讯研究中，动物种群中不可靠信号的维持仍然是一个极具争议的话题。甲壳类动物是研究力量不可靠信号的理想群体，因为它们的螯足肌肉隐藏在一个外骨骼下，使得竞争者很难通过视觉评估对手的力量。在这项研究中，我们研究了社会途径在调节甲壳类动物力量不可靠信号可能获得的优势方面的重要性。为此，我们调查了决定社会优势的因素，以及在雄性和雌性淡水小龙虾 Cherax destructor 的攻击性相遇中信号和战斗的相对重要性。与其他小龙虾物种一样，我们预计在给定的武器尺寸下，武器力量会有很大的变化，这使得仅通过信号来评估对手的实际战斗能力变得困难。此外，我们预计战斗将用于确保那些信号（即螯足）尺寸较弱的个体不会获得高于预期的优势。对于雄性和雌性 C. destructor，我们发现它们的螯足在任何给定的武器尺寸下的实际力量都有很大的变化，这表明竞争对手很难仅通过信号准确评估对手的力量。对于雄性来说，这些力量不可靠的信号通过增加战斗水平和减少对信号的依赖来进行社会控制，从而直接限制了那些仅拥有高质量信号（大螯足）而资源持有潜力低的个体获得的利益。然而，与我们的预测相反，我们发现雌性主要依赖信号来解决争端，从而导致力量不可靠的信号经常被用来建立优势。雌性依赖不可靠信号来确定优势，这突显了我们对动物通讯中不诚实行为的普遍性和分布的理解不足。
