Supplemental Tables and Datasets from Convergence of gut microbiota in myrmecophagous amphibians

The gut microbiome composition of terrestrial vertebrates is known to converge in response to common specialized dietary strategies, like leaf-eating (folivory) or ant- and termite-eating (myrmecophagy). To date, such convergence has been studied in mammals and birds, but has been neglected in amphibians. Here, we analysed 15 anuran species (frogs and toads) representing five Neotropical families and demonstrated the compositional convergence of the gut microbiomes of distantly related myrmecophagous species. Specifically, we found that the gut microbial communities of bufonids and microhylids, which have independently evolved myrmecophagy, were significantly more similar than expected based on their hosts' evolutionary divergence. Conversely, we found that gut microbiome composition was significantly associated with host evolutionary history in some cases. For instance, the microbiome composition of Xenohyla truncata—one of the few known amphibians that eat fruits—was not different from those of closely related tree frogs with an arthropod generalist diet. Bacterial taxa overrepresented in myrmecophagous species relative to other host families include Paludibacter, Treponema, and Rikenellaceae, suggesting diet-mediated selection and prey-to-predator transmission likely driving the observed compositional convergence. This study provides a basis for examining the roles of the gut microbiome in host tolerance and sequestration of toxic alkaloids from ants and termites.

已有研究表明，陆生脊椎动物的肠道菌群组成会因共同的特化饮食策略而发生趋同，例如食叶性（folivory）或食蚁性（myrmecophagy，即专性取食蚂蚁与白蚁）。迄今为止，这类菌群趋同现象的研究多集中于哺乳类与鸟类，两栖类相关研究尚未得到充分关注。本研究分析了隶属于5个新热带区（Neotropical）科的15种无尾目（anuran，涵盖蛙类与蟾蜍类）物种，证实了亲缘关系较远的食蚁性物种的肠道菌群组成存在趋同现象。具体而言，独立演化出食蚁性的蟾蜍科（Bufonidae）与姬蛙科（Microhylidae）物种，其肠道菌群群落的相似性显著高于基于宿主演化分化程度所预期的水平。反之，部分案例中肠道菌群组成也与宿主的演化历史存在显著关联。例如，截形异吻蛙（Xenohyla truncata）是目前已知少数以果实为食的两栖动物之一，其肠道菌群组成与亲缘关系相近的节肢动物广食性树蛙并无显著差异。相较于其他宿主类群，食蚁性物种中富集的细菌类群包括沼泽杆菌属（Paludibacter）、密螺旋体属（Treponema）与理研菌科（Rikenellaceae），这提示饮食介导的选择作用以及猎物向捕食者的菌群传播，或是本次观测到的菌群组成趋同现象的核心驱动因素。本研究为探讨肠道菌群在宿主耐受与螯合蚂蚁、白蚁所携带的有毒生物碱过程中所发挥的作用提供了重要研究基础。