Differential learning by native versus invasive predators to avoid distasteful cleaning mutualists

Abstract Cleaning symbioses on coral reefs are mutually beneficial interactions between two individuals, in which a ‘cleaner’ removes and eats parasites from the surface of ‘client’ fish. A suite behavioural morphological traits cleaners signal cooperation with co‐evolved species, thus protecting cleaner being eaten by otherwise predatory clients. However, it is unclear whether clients innate or learned, therefore an introduced predator might consume, cooperate alter behaviour cleaners. We explored role learning cleaning comparing native fishes both naïve experienced, non‐native fish predators. In so doing, we tested vulnerability predominant Atlantic reefs, gobies ( Elacatinus spp.), to recent introduction generalist predator, Indo‐Pacific red lionfish Pterois volitans ). Naïve juveniles invasive P. ) predators Cephalopholis spp. groupers) initially attacked hyperventilated putative toxin gobies' skin during laboratory experiments. After one five such encounters, often approached closely, then turned away without striking. Consistent learned avoidance, rarely interacted wild, either antagonistically cooperatively, did not affect abundance. Native showed little evidence early encounters; they repeatedly experiments less violently than lionfish. consistent cooperation, antagonised were frequently cleaned wild. demonstrated that rapid, avoidance protects distasteful mutualist predator. The plasticity this invader likely contributes its success across invaded range. Additionally, our results suggest cleaner's chemical defence most evolved as way deter predation reinforce individuals species.