Data from: Genetic structure of native ant supercolonies varies in space and time

Ant supercolonies are the largest cooperative units known in nature. They consist of networks of interconnected nests with hundreds of reproductive queens, where individuals move freely between nests, cooperate across nest boundaries and show little aggression towards non-nestmates. The combination of high queen numbers and free mixing of workers, queens and brood between nests results in extremely low nestmate relatedness. In such low-relatedness societies, cooperative worker behaviour appears maladaptive because it may aid random individuals instead of relatives. Here, we provide a comprehensive picture of genetic substructure in supercolonies of the native wood ant Formica aquilonia using traditional population genetic as well as network analysis methods. Specifically, we test for spatial and temporal variation in genetic structure of different classes of individuals within supercolonies and analyse the role of worker movement in determining supercolony genetic networks. We find that relatedness within supercolonies is low but positive when viewed on a population level, which may be due to limited dispersal of individuals and/or ecological factors such as nest site limitation and competition against conspecifics. Genetic structure of supercolonies varied with both sample class and sampling time point, which indicates that mobility of individuals varies according to both caste and season and suggests that generalizing has to be carried out with caution in studies of supercolonial species. Overall, our analysis provides novel evidence that native wood ant supercolonies exhibit fine-scale genetic substructure, which may explain the maintenance of cooperation in these low-relatedness societies.

蚂蚁超级群落（supercolony）是自然界已知的规模最大的合作单元。它们由相互连通的蚁巢网络构成，内含数百只繁殖型蚁后，群落内个体可在不同蚁巢间自由移动，跨巢边界开展合作，且对非本巢同伴几乎无攻击性。高数量蚁后与工蚁、蚁后及幼体（brood）在巢间自由混合的共同作用，导致巢伴间的遗传亲缘度极低。在这类低亲缘度社会中，工蚁的合作行为看似适应不良，因为其帮助的可能是随机个体而非亲缘个体。本研究采用传统种群遗传学与网络分析方法，对本土林蚁（Formica aquilonia）的超级群落遗传亚结构进行了全面解析。具体而言，本研究检验了超级群落内不同类群个体的遗传结构在空间与时间上的变异，并分析了工蚁移动对塑造超级群落遗传网络的作用。研究结果显示，在种群水平上，超级群落内部的亲缘度虽低但呈正值，这可能源于个体扩散受限，以及巢址限制、同种个体间竞争等生态因素。超级群落的遗传结构随采样类群与采样时间点的不同而发生变化，这表明个体的移动能力会因品级（caste）与季节而异，同时也提示，在对超级群落物种开展研究时，需谨慎进行结论泛化。综上，本研究的分析为本土林蚁超级群落存在精细尺度的遗传亚结构提供了新证据，这一发现或可解释这类低亲缘度社会中合作行为的维持机制。