Geographical variation in the benefits obtained by a coral reef fish mimic

Mimicry systems are frequently categorized by the type of benefit gained by the mimicʹs resemblance to its model: protection from threat, including predation (protective mimicry), and increased access to resources, including prey items (aggressive mimicry). These category types may not be mutually exclusive, and some mimics may gain more than one type of benefit. Here we examined a contentious classic textbook example of mimicry between the cleaner wrasse Labroides dimidiatus and its mimic, the sabre-toothed blenny Aspidontus taeniatus. We found that the benefit obtained by the sabre-toothed blenny varied between four geographical locations. At the Great Barrier Reef, in Indonesia and in the Red Sea, it rarely attacked reef fish victims, but instead relied on other food sources such as substrate items, damselfish eggs and tubeworms. Here, the main function of the mimicry system could be to protect the sabre-toothed blenny from predation (protective mimicry) and was consistent with a previous study in Japan. However, in French Polynesia, the sabre-toothed blenny aggressively attacked reef fish frequently, and potential victims were more likely to pose to solicit a cleaning interaction. Diet analysis from individuals in French Polynesia indicated material was gleaned from the surface of fish, including large pieces of fin, implying an increase in the benefits obtained from attacking reef fish (aggressive mimicry). This study provides a potential second example of a mimicry system in which multiple types of benefits are gained by a mimic, and importantly, that the benefits obtained by the mimic vary between different environmental conditions and/or geographical locations. This may have important implications for the maintenance and evolution of mimicry systems and may reflect different stages of an arms race with potential victims.