Kin selection and reciprocation of biological services are distinct theories invoked to explain the origin and evolutionary maintenance of altruistic and cooperative behaviors. Although these behaviors are not considered to be mutually exclusive, the cost-benefit balance of behaving altruistically or cooperating reciprocally and the conditions promoting a switch between such different strategies have rarely been tested. Here, we examine the association between allofeeding, allopreening, and vocal solicitations in wild barn owl (Tyto alba) broods under different food abundance conditions: natural food provisioning and after an experimental food supplementation. Allofeeding was performed mainly by elder nestlings (hatching is asynchronous) in prime condition, especially when the cost of forgoing a prey was small (when parents allocated more prey to the food donor and after food supplementation). Nestlings preferentially shared food with the siblings that emitted very intense calls, thus potentially increasing indirect fitness benefits, or with the siblings that provided extensive allopreening to the donor, thus possibly promoting direct benefits from reciprocation. Finally, allopreening was mainly directed toward older siblings, perhaps to maximize the probability of being fed in return. Helping behavior among relatives can therefore be driven by both kin selection and direct cooperation, although it is dependent on the contingent environmental conditions.

中文翻译：

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仓Bar长老可根据兄弟姐妹的需要或分配给其他人灵活地重新分配父母的食物。

生物服务的亲缘关系选择和往复运动是用来解释利他行为和合作行为的起源和进化维持的独特理论。尽管这些行为不被认为是相互排斥的，但很少测试利他行为或相互合作的成本－收益平衡以及促进这种不同策略之间转换的条件。在这里，我们研究了野生谷仓猫头鹰（Tyto alba）的同种异食，同种异体繁殖和声带诱饵之间的关联。）不同食物丰度条件下的育雏：天然食物供应和实验性食物补充后的繁殖。异体喂养主要是在条件良好的情况下，由年长的雏鸟（孵化是异步的）进行的，特别是在放弃猎物的成本较小时（当父母将更多猎物分配给食物供体时和补充食物后）。雏鸟优先与发出非常强烈的呼声的兄弟姐妹共享食物，从而潜在地增加间接健身的好处，或者与向捐助者广泛分配的兄弟姐妹共享食物，从而可能促进往复运动的直接好处。最后，Allopreening主要针对年长的兄弟姐妹，也许是为了最大程度地提高被喂食的可能性。