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

中文翻译：

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本地捕食者与入侵捕食者的差异学习，以避免令人反感的清洁互惠主义者

1. 珊瑚礁上的清洁共生体是两个人之间互利的互动，其中“清洁工”从“客户”鱼的表面清除并吃掉寄生虫。清洁工的一系列行为和形态特征表明与共同进化的物种合作，从而保护清洁工免于被其他掠夺性客户吃掉。然而，尚不清楚清洁工和掠夺性客户之间的合作是先天的还是后天习得的，因此引入的捕食者是否可能会消费、合作或改变清洁工的行为。
2. 我们通过比较本地清洁鱼类与幼稚和经验丰富的非本地和本地鱼类捕食者的相互作用，探索了学习在清洁共生中的作用。在这样做的过程中，我们测试了大西洋珊瑚礁上主要的清洁工、清洁虾虎鱼 ( Elacatinus spp.) 对最近引入的通用捕食者印度-太平洋红狮子鱼 ( Pterois volitans )的脆弱性。
3. 侵入性（P. volitans）和本地捕食者（Cephalopholis）的幼稚幼鱼属 石斑鱼）最初攻击清洁虾虎鱼，并在实验室实验期间因虾虎鱼皮肤上的假定毒素而过度呼吸。一到五次这样的遭遇之后，入侵的狮子鱼经常靠近清洁工，然后转身离开而不打人。与习得性回避一致，侵入性狮子鱼很少与野外清洁虾虎鱼互动，无论是对抗性还是合作性，并且不会影响虾虎鱼的数量。本地掠食者在早期遭遇中几乎没有学习的迹象。在实验室实验中，它们反复攻击清洁器，并且比狮子鱼更不猛烈地换气。然而，与习得的合作一致，本地捕食者很少对抗，并且经常被野外的虾虎鱼清理。
4. 我们证明了快速、习得的回避可以保护令人讨厌的清洁共生者免受入侵性捕食者的侵害。这种入侵者的行为可塑性可能有助于其在其入侵范围内取得成功。此外，我们的结果表明，清洁工的化学防御很可能演变为一种阻止捕食和加强与本地物种幼稚个体合作的方式。