Social Punishment of Dishonest Signalers Caused by Mismatch between Signal and Behavior

Many animals use conventional signals of fighting ability to mediate aggressive conflict. Given the apparent benefits of signaling inaccurately high fighting ability, there is extensive interest in why animals communicate their abilities honestly [1]. One hypothesis is that inaccurate signalers receive social punishment that disfavors inaccuracy. Although the idea that social punishment can prevent dishonesty is appealing, questions about the evolutionary stability of this hypothesis remain [2]. For example, how do individuals know a rival is cheating? We independently manipulated a signal of fighting ability and agonistic behavior in Polistes dominulus wasps to test the behavioral mechanisms underlying social punishment. Remarkably, a mismatch between signal and behavior caused social punishment. Individuals with experimentally altered signals received more aggression from rivals. Individuals with experimentally altered behavior were less able to establish dominance relationships. In contrast, control individuals and those with experimentally altered signal and behavior suffered neither cost. They received little aggression and established stable dominance relationships. Therefore, individuals use information about the match between signal and behavior to assess the accuracy of rival signals. A mismatch produces costly social interactions. This simple behavioral mechanism provides a clear cost to signal inaccuracy that may maintain honest communication over evolutionary time.