Department of Entomology, University of Arizona, Tucson, AZ 85721, USA.
Mol Ecol. 2012 May;21(9):2282-96. doi: 10.1111/j.1365-294X.2011.05464.x. Epub 2012 Jan 25.
Ants dominate many terrestrial ecosystems, yet we know little about their nutritional physiology and ecology. While traditionally viewed as predators and scavengers, recent isotopic studies revealed that many dominant ant species are functional herbivores. As with other insects with nitrogen-poor diets, it is hypothesized that these ants rely on symbiotic bacteria for nutritional supplementation. In this study, we used cloning and 16S sequencing to further characterize the bacterial flora of several herbivorous ants, while also examining the beta diversity of bacterial communities within and between ant species from different trophic levels. Through estimating phylogenetic overlap between these communities, we tested the hypothesis that ecologically or phylogenetically similar groups of ants harbor similar microbial flora. Our findings reveal: (i) clear differences in bacterial communities harbored by predatory and herbivorous ants; (ii) notable similarities among communities from distantly related herbivorous ants and (iii) similar communities shared by different predatory army ant species. Focusing on one herbivorous ant tribe, the Cephalotini, we detected five major bacterial taxa that likely represent the core microbiota. Metabolic functions of bacterial relatives suggest that these microbes may play roles in fixing, recycling, or upgrading nitrogen. Overall, our findings reveal that similar microbial communities are harbored by ants from similar trophic niches and, to a greater extent, by related ants from the same colonies, species, genera, and tribes. These trends hint at coevolved histories between ants and microbes, suggesting new possibilities for roles of bacteria in the evolution of both herbivores and carnivores from the ant family Formicidae.
蚂蚁在许多陆地生态系统中占据主导地位，但我们对它们的营养生理学和生态学知之甚少。虽然传统上被视为捕食者和食腐动物，但最近的同位素研究表明，许多优势蚂蚁物种是功能性的草食动物。与其他以低氮饮食为主的昆虫一样，人们假设这些蚂蚁依赖共生细菌来进行营养补充。在这项研究中，我们使用克隆和 16S 测序技术进一步描述了几种草食性蚂蚁的细菌菌群，同时还研究了不同营养水平的蚂蚁物种内部和之间细菌群落的β多样性。通过估计这些群落之间的系统发育重叠，我们检验了以下假设：生态或系统发育上相似的蚂蚁群体拥有相似的微生物菌群。我们的研究结果表明：（i）捕食性和草食性蚂蚁所携带的细菌群落存在明显差异；（ii）来自不同草食性蚂蚁的群落之间存在显著的相似性；（iii）不同捕食性行军蚁物种之间存在相似的群落。研究集中在一个草食性蚂蚁部落，即 Cephalotini，我们检测到五个主要的细菌类群，它们可能代表核心微生物群。细菌相关物的代谢功能表明，这些微生物可能在固定、回收或升级氮方面发挥作用。总体而言，我们的研究结果表明，来自相似营养生态位的蚂蚁以及来自同一蚁群、物种、属和部落的亲缘关系密切的蚂蚁，其体内都携带有相似的微生物群落。这些趋势表明蚂蚁和微生物之间存在共同进化的历史，这为细菌在蚂蚁科 Formicidae 中草食动物和肉食动物的进化中所扮演的角色提供了新的可能性。
