Automimicry destabilizes aposematism: predator sample-and-reject behaviour may provide a solution

Area of Science:

• Ecology
• Evolutionary Biology
• Animal Behavior

Background:

• Aposematism, the use of warning coloration to signal unpalatability, is a widely studied natural signaling system.
• The evolutionary stability of aposematism is challenged by automimicry, where palatable individuals mimic unpalatable ones.
• Automimics can destabilize signaling systems by gaining protection without the cost of unpalatability.

Purpose of the Study:

• To investigate how the frequency of palatable automimics affects predator sampling behavior.
• To determine if predator sampling behavior exerts selection pressure against automimics.
• To understand the role of predator sampling in maintaining the stability of aposematic signaling.

Main Methods:

• Experiments using domestic chicks (Gallus gallus domesticus) as predators.
• Chicks were trained to discriminate between green (signaling) and brown (control) chick crumbs.
• Green crumbs were either unpalatable (quinine-treated) or palatable, with varying frequencies of palatable items across four treatments.

Main Results:

• Predator sampling behavior was significantly influenced by the frequency of automimics.
• Chicks demonstrated the ability to discriminate between palatable mimics and unpalatable models through sampling.
• This sampling behavior by predators provides a selection pressure that can counteract the destabilizing effect of automimics.

Conclusions:

• Predator sampling behavior is crucial for the evolutionary stability of aposematic signaling systems.
• Surprisingly, the stability of aposematism relies on predators that are not fully deterred by warning signals.
• Predator learning and discrimination through cautious sampling maintain the integrity of warning coloration.