Acoustic Signals, Arms Races and the Costs of Honest Signalling

Animal signals evolve as adaptations to as well as physical environments. Where the interests of signallers and responders differ, a coevolutionary arms race cycle of signal adoption, exaggeration, and devaluation may result. Stable, reliable signals evolve when costs of signalling constrain the evolution of bluff and exaggeration. Acoustic signals are especially costly, compared to other signal types, and are therefore especially likely to evolve as reliable signals in such social competition situations. Costs of acoustic signals include physiological costs of growth and signal production, probes by conspecific rivals and discriminating members of the other sex, and attacks by natural enemies such as predators and parasites.