Data from: Nest inheritance is the missing source of direct fitness in a primitively eusocial insect

Animals that co-operate with non-relatives represent a challenge to inclusive fitness theory, unless co-operative behavior is shown to provide direct fitness benefits. Inheritance of breeding resources could provide such benefits, but this route to co-operation has been little investigated in the social insects. We show that nest inheritance can explain the presence of unrelated helpers in a classic social insect model, the primitively eusocial wasp Polistes dominulus. We found that subordinate helpers produced more direct offspring than lone breeders, some while still subordinate but most after inheriting the dominant position. Thus, while indirect fitness obtained through helping relatives has been the dominant paradigm for understanding eusociality in insects, direct fitness is vital to explain co-operation in P. dominulus.

与非亲属开展合作的动物，对广义适合度理论构成了理论挑战——除非此类合作行为被证实能够为个体带来直接适合度收益。繁殖资源的继承或许可提供此类收益，但在社会性昆虫中，这一合作演化路径尚未得到充分研究。我们证实，巢穴继承能够解释社会性昆虫经典模型物种——原始真社会性胡蜂（Polistes dominulus）中非亲属帮手的存在。研究发现，处于从属地位的帮手所产生的直接后代数量多于独居繁殖者；其中部分个体在仍保有从属地位时便已繁殖，但绝大多数是在继承优势繁殖地位之后。因此，尽管通过帮助亲属获取间接适合度，一直是阐释昆虫真社会性的主流研究范式，但直接适合度才是解释P. dominulus合作行为的关键所在。