Many crustaceans use their large claws to signal fighting ability during territorial contests. However, the size of a claw does not always reflect its strength or the bearer's ability to fight. If strength predicts the outcome of a fight, the mismatch between the size and strength of a claw creates dishonest signalling. Still, only a handful of species have been studied, leaving a gap in our knowledge of the taxonomic diversity and evolutionary history of dishonest signalling. To help fill this gap, we studied signalling and fighting between virile crayfish, Faxonius virilis. First, we measured the relationship between the size and strength of a claw in males and females. Then, we staged encounters between members of the same sex to determine how carapace length, claw size and claw strength influence the probability of fighting and the probability of winning. Both males and females possessed claws whose size poorly predicted their strength, especially at larger sizes. Unlike other species, which escalate aggression based on claw size, virile crayfish escalated aggression based on relative body size. When fighting occurred, however, both body size and claw strength determined the winner. Likely, virile crayfish ignore claw size because body size provides a more reliable signal of dominance. Our results stress the importance of observing behavioural dynamics in addition to functional relationships when studying the potential for dishonest signalling.

中文翻译：

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强壮的小龙虾根据体型而不是武器大小来升级攻击性

许多甲壳类动物在领土争夺中使用它们的大爪子来表示战斗能力。然而，爪子的大小并不总是反映它的力量或持有者的战斗能力。如果力量可以预测战斗的结果，那么爪子的大小和力量之间的不匹配会产生不诚实的信号。尽管如此，只研究了少数物种，这在我们对分类多样性和不诚实信号的进化历史的了解方面留下了空白。为了帮助填补这一空白，我们研究了雄性小龙虾 Faxonius virilis 之间的信号传递和战斗。首先，我们测量了雄性和雌性爪子的大小和强度之间的关系。然后，我们在同性成员之间上演了相遇，以确定甲壳的长度，爪子大小和爪子力量影响战斗的概率和获胜的概率。雄性和雌性都有爪子，它们的大小不能很好地预测它们的力量，尤其是在较大的尺寸时。与根据爪子大小升级攻击性的其他物种不同，强壮的小龙虾根据相对体型升级攻击性。然而，当战斗发生时，体型和爪子的力量决定了胜利者。可能，强壮的小龙虾忽略爪子的大小，因为体型提供了更可靠的优势信号。我们的结果强调了在研究不诚实信号的可能性时，除了观察功能关系之外，观察行为动态的重要性。根据爪子大小来升级攻击性，而强壮的小龙虾则根据相对体型来升级攻击性。然而，当战斗发生时，体型和爪子的力量决定了胜利者。可能，强壮的小龙虾忽略爪子的大小，因为体型提供了更可靠的优势信号。我们的结果强调了在研究不诚实信号的可能性时，除了观察功能关系之外，观察行为动态的重要性。根据爪子大小来升级攻击性，而强壮的小龙虾则根据相对体型来升级攻击性。然而，当战斗发生时，体型和爪子的力量决定了胜利者。可能，强壮的小龙虾忽略爪子的大小，因为体型提供了更可靠的优势信号。我们的结果强调了在研究不诚实信号的可能性时，除了观察功能关系之外，观察行为动态的重要性。