Data from: Polygyny does not explain the superior competitive ability of dominant ant associates in the African ant-plant, Acacia (Vachellia) drepanolobium

1. The Acacia drepanolobium (also known as Vachellia drepanolobium) ant-plant symbiosis is considered a classic case of species coexistence, in which four species of tree-defending ants compete for nesting space in a single host tree species. Coexistence in this system has been explained by trade-offs in the ability of the ant associates to compete with each other for occupied trees versus the ability to colonize unoccupied trees. 2. We seek to understand the proximal reasons for how and why the ant species vary in competitive or colonizing abilities, which are largely unknown. 3. In this study, we use RADseq derived SNPs to identify relatedness of workers in colonies to test the hypothesis that competitively dominant ants reach large colony sizes due to polygyny, i.e., the presence of multiple egg-laying queens in a single colony. 4. We find that variation in polygyny is not associated with competitive ability; in fact, the most dominant species, unexpectedly, showed little evidence of polygyny. We also use these markers to investigate variation in mating behavior among the ant species, and find that different species vary in the number of males fathering the offspring of each queen. Finally, we show that the nature of polygyny varies between the two commonly polygynous species, Crematogaster mimosae and Tetraponera penzigi: in C. mimosae, queens in the same colony are often related, while this is not the case for T. penzigi. 5. These results shed light on factors influencing the evolution of species coexistence in an ant-plant mutualism, as well as demonstrating the effectiveness of RADseq-derived SNPs for parentage analysis.1. 镰荚金合欢（Acacia drepanolobium，又名Vachellia drepanolobium）蚁植共生体系被视作物种共存研究的经典案例，该体系中共有4种护树蚂蚁，在单一寄主树种上争夺筑巢空间。该体系下的物种共存现象，可通过蚁类共生伙伴在抢占已占据宿主树的竞争能力与定植未被占据宿主树的能力之间存在的权衡效应得到解释。 2. 目前学界对不同蚂蚁物种在竞争与定植能力上存在差异的近端原因仍知之甚少，本研究旨在阐明这一问题。 3. 本研究利用RADseq测序获得的单核苷酸多态性（Single Nucleotide Polymorphism, SNPs）标记，通过鉴定蚁群内工蚁的亲缘关系，验证如下假说：具有竞争优势的蚂蚁之所以能够形成大型蚁群，是因为其存在多后现象（polygyny），即单个蚁群内存在多只可产卵的蚁后。 4. 研究结果显示，多后现象的差异与蚂蚁的竞争能力并无关联；事实上，最具竞争优势的蚂蚁物种几乎未表现出多后现象，这一结果与预期相悖。本研究同时利用上述分子标记探究了不同蚂蚁物种的交配行为差异，发现不同物种在每只蚁后后代的父本雄性数量上存在显著差异。此外，本研究还发现两种常见的多后蚁类——细胸举腹蚁（Crematogaster mimosae）与彭氏四节蚁（Tetraponera penzigi），其多后现象的本质存在差异：细胸举腹蚁的同群蚁后往往具有亲缘关系，而彭氏四节蚁的蚁群则并非如此。 5. 本研究结果不仅阐明了影响蚁-植物互利共生体系中物种共存演化的相关因素，同时也验证了RADseq测序衍生的SNPs标记在亲权分析中的应用有效性。