Institute of Ecology and Evolution, University of Bern, Wohlenstr. 50a, CH-3032, Hinterkappelen, Switzerland.
Sci Rep. 2017 Jun 21;7(1):4010. doi: 10.1038/s41598-017-03841-3.
If individuals help more those who have previously helped them, stable cooperation may ensue through alternation of roles between donors and recipients. Allogrooming, which is costly to donors and beneficial to recipients, is often exchanged between social partners. Arguably, allogrooming and allopreening are the most frequently exchanged social services and have been used as a standard model of reciprocal cooperation. However, evidence for the application of reciprocity rules among social partners allogrooming each other hitherto is merely correlational. Here, we tested whether female Norway rats (Rattus norvegicus) apply the decision rule characterising direct reciprocity: help someone who has helped you before, by experimentally manipulating both the need for allogrooming and the behavioural response. Furthermore, we checked whether trading of grooming services is influenced by the rank of the social partner. We show that rats groom social partners reciprocally and prefer to do so up the hierarchy, i.e. they groom dominant partners more often than subordinates, while reciprocating with both. This provides experimental evidence that animals render a costly social service by applying reciprocity decision rules when showing a natural hygienic behaviour. The fact that allogrooming is more readily shown up the hierarchy may suggest an appeasing function.
如果个体更多地帮助那些之前帮助过他们的人,那么通过捐赠者和接受者之间角色的交替,稳定的合作可能会随之而来。 allo 梳理,这对捐赠者来说是昂贵的,但对接受者有益,通常在社会伙伴之间交换。可以说, allo 梳理和 allo 理毛是最常交换的社会服务,并被用作互惠合作的标准模型。然而,迄今为止,关于相互梳理的社会伙伴之间互惠规则的应用的证据仅仅是相关的。在这里,我们测试了雌性挪威鼠(Rattus norvegicus)是否应用了直接互惠所特有的决策规则:通过实验操纵 allo 梳理的需求和行为反应,帮助以前帮助过你的人。此外,我们还检查了梳理服务的交易是否受到社会伙伴等级的影响。我们发现,老鼠互惠地梳理社交伙伴,并倾向于在等级制度中这样做,即它们更频繁地梳理支配性伙伴,而不是下属伙伴,同时也与两者互惠。这提供了实验证据,表明动物在表现出自然的卫生行为时,通过应用互惠决策规则来提供昂贵的社会服务。 allo 梳理更容易在等级制度中表现出来的事实可能表明它具有安抚功能。