Distinguishing between unreliability and dishonesty: a comparative study of aggressive communication in crayfish

A major challenge in the study of animal communication is distinguishing whether signals convey honest or dishonest information. Biologists infer the honesty of a signal from its correlation with the information being signaled (e.g., fecundity or fighting ability) — the better the correlation, the more honest the signal.
However, this view of signaling potentially conflates unreliable indicators with dishonest signals. Just because a trait conveys unreliable information does not mean that the structure serves as a dishonest signal; developmental noise, genetic drift, and environmental constraints can reduce the covariation between a putative signal and an organism’s quality. Moreover, a trait must influence the behavior of other organisms to qualify as a signal.
We studied how a putative signal, claw size, affects physical performance and social dominance in three species of stream-dwelling crayfish, which fight routinely over resources. For comparison, we measured the relationsh...