  Current evolutionary theory suggests that many natural signaling systems
evolved from preexisting cues. In aposematic systems, prey warning signals
benefit both predator and prey. When the signal is highly beneficial, a third
species often evolves to mimic the unpalatable species, exploiting the
signaling system for its own protection. We investigated the evolutionary
development of predator cue utilization and prey signaling in a digital
predator-prey system in which mimicking prey could evolve to alter their
appearance to resemble poison-free or poisonous prey. In predators, we observed
rapid evolution of cue recognition (i.e. active behavioral responses) when
presented with sufficiently poisonous prey. In addition, active signaling (i.e.
mimicry) evolved in prey under all conditions that led to cue utilization. Thus
we show that despite imperfect and dishonest signaling, given a high cost of
consuming poisonous prey, complex systems of interspecific communication can
evolve via predator cue recognition and prey signal manipulation. This provides
evidence supporting hypotheses that cues may serve as stepping-stones in the
evolution of more advanced communication systems and signals incorporating
information about the environment.
