Data from: Using social parasitism to test reproductive skew models in a primitively eusocial wasp

Remarkable variation exists in the distribution of reproduction (skew) among members of cooperatively breeding groups, both within and between species. Reproductive skew theory has provided an important framework for understanding this variation. In the primitively eusocial Hymenoptera, two models have been routinely tested: concessions models, which assume complete control of reproduction by a dominant individual, and tug-of-war models, which assume on-going competition among group members over reproduction. Current data provide little support for either model, but uncertainty about the ability of individuals to detect genetic relatedness and difficulties in identifying traits conferring competitive ability mean that the relative importance of concessions versus tug-of-war remains unresolved. Here, we suggest that the use of social parasitism to generate meaningful variation in key social variables represents a valuable opportunity to explore the mechanisms underpinning reproductive skew within the social Hymenoptera. We present a direct test of concessions and tug-of-war models in the paper wasp Polistes dominulus by exploiting pronounced changes in relatedness and power structures that occur following replacement of the dominant by a congeneric social parasite. Comparisons of skew in parasitized and unparasitized colonies are consistent with a tug-of-war over reproduction within P. dominulus groups, but provide no evidence for reproductive concessions.

合作繁殖群体的成员间乃至不同物种之间，生殖倾斜（reproductive skew）的分布均存在显著差异。生殖倾斜理论为理解这类变异提供了重要的分析框架。在原初真社会性膜翅目（primitively eusocial Hymenoptera）类群中，两类模型常被用于相关研究：一类是让步模型（concessions models），其假设优势个体对繁殖行为拥有完全控制权；另一类是拔河模型（tug-of-war models），其假定群体成员间围绕繁殖权存在持续竞争。现有数据几乎无法为任一模型提供有效支撑，但由于个体检测遗传亲缘关系的能力尚存争议，且识别赋予竞争优势的性状存在技术难度，因此让步模型与拔河模型的相对重要性仍未明确。在此我们提出，利用社会寄生（social parasitism）在关键社会变量中产生具有生物学意义的差异，为探究社会膜翅目类群内生殖倾斜的调控机制提供了宝贵契机。本研究借助同属社会寄生者替换优势个体后引发的亲缘关系与权力结构的显著变化，对纸巢胡蜂（Polistes dominulus）群体中的两类模型进行了直接检验。对寄生与未寄生蜂群的生殖倾斜情况进行比较后发现，结果支持纸巢胡蜂群体内存在繁殖权拔河竞争的结论，但未发现生殖让步的相关证据。