Helping behaviour in some cooperative breeders is apparently maintained by a combination of coercion and reciprocity. In such pay-to-stay systems, alloparental brood care of subordinate group members functions as a service to dominants, which tolerate subordinates based on how much help they provide. Cooperative territory defence is a key task of cooperative breeders, but it is unknown how territory defence by subordinates is socially regulated. Diverse costs and benefits associated with defending the territory against different threats suggest that these defence behaviours may be maintained through divergent selection regimes, and they might be regulated through different social processes. In the cooperatively breeding cichlid fish Neolamprologus pulcher, unrelated subordinates help defend the territory against egg predators even if they do not participate in reproduction and therefore do not suffer direct or indirect fitness costs through predators of eggs. This behaviour has therefore been interpreted as altruistic service to dominants. Subordinates also defend the group territory against predators of juveniles and adults, which might at least partly reflect their own direct fitness interests and could be maintained through mutualistic interactions among group members. Here, we directly compared the regulation of these two types of defence behaviours and tested whether they are enforced by breeders. We prevented subordinates from defending the territory against egg predators or predators of adults and observed whether they received more aggression in response to this treatment. We found that subordinates received more aggression from breeders after withholding defence against egg predators, but not after withholding defence against fish predators. This suggests that territory defence against egg predators by helpers is enforced by breeders and hence subject to negotiations and trading, whereas defence against fish predators is probably based on mutualistic fitness benefits.

中文翻译：

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在合作繁殖慈鲷时，惩罚控制辅助防御卵捕食者而不是鱼类捕食者

一些合作育种者的帮助行为显然是通过强制和互惠的结合来维持的。在这样的付费住宿系统中，对下属群体成员的异体亲子照料起到了对统治者的服务的作用，统治者根据他们提供的帮助程度来容忍下属。合作领地防御是合作育种者的一项关键任务，但下属的领地防御如何受到社会规范尚不清楚。与保护领土免受不同威胁相关的不同成本和收益表明，这些防御行为可以通过不同的选择机制来维持，并且可以通过不同的社会过程进行调节。在合作养殖慈鲷鱼 Neolamprologus pulcher 中，不相关的下属即使不参与繁殖，也有助于保护领土免受蛋捕食者的侵害，因此不会因蛋捕食者而遭受直接或间接的适应成本。因此，这种行为被解释为对支配者的无私服务。下属还保护群体领土免受少年和成年人的掠夺者的侵害，这可能至少部分反映了他们自己的直接健康利益，并且可以通过群体成员之间的互惠互利来维持。在这里，我们直接比较了这两种防御行为的监管，并测试了它们是否由饲养员强制执行。我们阻止下属保卫领土免受蛋食肉动物或成年人的食肉动物的侵害，并观察他们是否因这种待遇而受到更多的攻击。我们发现，下属在拒绝对卵食肉动物的防御后，从饲养员那里得到了更多的攻击，但在对鱼类掠食者的防御却没有后。这表明辅助者对蛋捕食者的领土防御是由育种者强制执行的，因此需要进行谈判和交易，而对鱼类捕食者的防御可能是基于互惠的健康利益。