Distinguishing between unreliability and dishonesty: a comparative study of aggressive communication in crayfish
Graham, Zackary; Angilletta, Michael (2021), Distinguishing between unreliability and dishonesty: a comparative study of aggressive communication in crayfish, Dryad, Dataset, https://doi.org/10.5061/dryad.18931zcz7
- 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 relationship between claw size and claw strength in three species of burrowing crayfish, which do not fight.
- In all species, crayfish with larger claws were not necessarily stronger, indicating that claw size poorly indicates claw strength. However, claw size is unlikely to function as a dishonest signal of fighting ability in these species for two reasons. First, claw size unreliably indicates claw strength in both the stream-dwelling species and the burrowing species. Second, relative claw size poorly predicted whether stream-dwelling crayfish would escalate aggression, questioning whether claw size serves as a signal. Instead, stream-dwelling crayfish escalated aggression based on their relative body size.
- Our results highlight the importance of observing behavior when determining the honesty of a signal. As such, future studies must distinguish between phenotypes that are unreliable indicators (or reliable indicators) from phenotypes that have been selected for dishonest (or honest) signaling.