Data from: Bacterial symbiont sharing in Megalomyrmex social parasites and their fungus-growing ant hosts

Bacterial symbionts are important fitness determinants of insects. Some hosts have independently acquired taxonomically related microbes to meet similar challenges, but whether distantly related hosts that live in tight symbiosis can maintain similar microbial communities has not been investigated. Varying degrees of nest sharing between Megalomyrmex social parasites (Solenopsidini) and their fungus-growing ant hosts (Attini) from the genera Cyphomyrmex, Trachymyrmex and Sericomyrmex allowed us to address this question, as both ant lineages rely on the same fungal diet, interact in varying intensities and are distantly related. We used tag-encoded FLX 454 pyrosequencing and diagnostic PCR to map bacterial symbiont diversity across the Megalomyrmex phylogenetic tree, which also contains free-living generalist predators. We show that social parasites and hosts share a subset of bacterial symbionts, primarily consisting of Entomoplasmatales, Bartonellaceae, Acinetobacter, Wolbachia and Pseudonocardia and that Entomoplasmatales and Bartonellaceae can co-infect specifically associated combinations of hosts and social parasites with identical 16S rRNA genotypes. We reconstructed in more detail the population-level infection dynamics for Entomoplasmatales and Bartonellaceae in Megalomyrmex symmetochus guest ants and their Sericomyrmex amabilis hosts. We further assessed the stability of the bacterial communities through a diet manipulation experiment and evaluated possible transmission modes in shared nests such as consumption of the same fungus garden food, eating of host brood by social parasites, trophallaxis and grooming interactions between the ants, or parallel acquisition from the same nest environment. Our results imply that cohabiting ant social parasites and hosts may obtain functional benefits from bacterial symbiont transfer even when they are not closely related.细菌共生体（bacterial symbionts）是昆虫重要的适合度决定因子。部分寄主已独立获得分类学上相关的微生物以应对相似的生存挑战，但目前尚未有研究探讨处于紧密共生关系的远缘寄主能否维持相似的微生物群落。来自圆胸切叶蚁属（Cyphomyrmex）、粗切叶蚁属（Trachymyrmex）和丝盾切叶蚁属（Sericomyrmex）的、隶属于盗蚁族（Solenopsidini）的巨首蚁属（Megalomyrmex）社会性寄生蚁及其隶属于切叶蚁族（Attini）的寄主之间存在不同程度的巢穴共享行为，这为我们解答该问题提供了研究体系——这两类蚁类均依赖相同的真菌食谱，互动强度存在差异且亲缘关系较远。我们采用标签编码FLX 454焦磷酸测序（tag-encoded FLX 454 pyrosequencing）与诊断PCR（diagnostic PCR）技术，在涵盖自由生活广食性捕食者的巨首蚁属系统发育树中，绘制了细菌共生体的多样性分布图谱。研究发现，社会性寄生蚁与寄主共享一部分细菌共生体，主要包括虫原体目（Entomoplasmatales）、巴尔通体科（Bartonellaceae）、不动杆菌属（Acinetobacter）、沃尔巴克氏体属（Wolbachia）与假诺卡氏菌属（Pseudonocardia）；且虫原体目与巴尔通体科可通过完全一致的16S rRNA基因型（16S rRNA genotypes）共感染寄主与社会性寄生蚁的特异性组合。我们进一步针对对称巨首蚁（Megalomyrmex symmetochus）寄居蚁及其美丽丝盾切叶蚁（Sericomyrmex amabilis）寄主中的虫原体目与巴尔通体科，重建了种群水平的感染动态。我们还通过食谱操控实验评估了细菌群落的稳定性，并探讨了共享巢穴中可能的传播模式：取食相同的真菌圃食物、社会性寄生蚁取食寄主幼虫、蚁类间的交哺行为（trophallaxis）与梳理互动，或是从同一巢穴环境中平行获得共生菌。研究结果表明，即使亲缘关系较远，共同栖息的蚁类社会性寄生蚁与寄主仍可通过细菌共生体的传递获得功能性收益。