DISSERTATION RESEARCH: Functional ecology and evolution of an ant gut microbiome

在自然界中，隐藏的东西往往是最重要的。例如，在南美洲的热带雨林中，植真菌蚂蚁比其他任何食草动物消耗更多的叶类植被。在森林冠层中，其他蚂蚁可能占所有昆虫生物量的50%以上。但是这些微小的食草动物是如何影响森林生态系统的呢？答案可能在于一个更隐秘的参与者：细菌。像珊瑚礁、奶牛甚至人类一样，许多昆虫依靠共生微生物来增加它们的饮食。有迹象表明，细菌可能对食草动物起着特别重要的作用。蚂蚁，或以花蜜、花蜜和其他植物来源为主要食物的蚂蚁。然而，人们对食草蚂蚁的微生物伴侣的进化、生态和功能知之甚少。本研究旨在以热带冠层蚁属（Cephalotes）为模型系统，揭示围绕蚂蚁/细菌共生的一些谜团。头蚁是已知的最食草的蚂蚁之一，长期以来，人们一直知道它们的肠道里有异常密集的细菌或微生物群。利用下一代DNA测序技术，本研究将解决以下问题：头藻肠道细菌是否与宿主共同进化？头螺肠道微生物群在宿主物种、巢穴、位置和宿主发育过程中是如何变化的？大头菌肠道细菌的基因组能说明它们的功能吗？更广泛的影响：这些问题的答案将澄清细菌共生体在热带雨林生态中最重要和最不为人所知的元素之一中所起的作用。此外，本研究的数据和技术将有助于解开共生肠道群落本身的进化和生态动力学。这些社区对人类社会既有直接影响（通过炎症性肠病等疾病），也有间接影响（通过与蝗虫和蚜虫等农业害虫的联系），但对它们的了解仍然很少。这项研究将为学生提供测序和数据分析前沿领域的培训机会，研究结果将通过正在进行的博物馆和k12外展活动向公众传播。

In nature, the hidden things often make the most difference. For example, in the rainforests of South America, fungus-gardening ants consume more leafy vegetation than any other herbivore. In the forest canopy, other ants may compose more than 50% of all insect biomass. But how do these tiny herbivores affect the forest ecosystem? The answer may lie with an even more hidden player: bacteria. Like coral reefs, cows, and even humans, many insects rely on symbiotic microbes to augment their diets. There are hints that bacteria may play an especially important role for ?herbivorous? ants, or those ants whose diet consists primarily of nectar, extra-floral nectar, and other plant-derived resources. However, little is known about the evolution, ecology, and function of the microbial partners of herbivorous ants. This study aims to uncover some of the mysteries surrounding ant/bacteria symbioses using the canopy-dwelling tropical ant genus Cephalotes as a model system. Cephalotes are among the most herbivorous of known ants, and have long been known to host an unusually dense population of bacteria, or microbiome, in their guts. Using next-generation DNA sequencing technology, this study will address the following questions: Have Cephalotes gut bacteria co-evolved with their hosts? How does the Cephalotes gut microbiome change among host species, nests, locations, and across host development? What can the genomes of Cephalotes gut bacteria indicate about their function?Broader Impacts: The answers to these questions will clarify the role played by bacterial symbionts in one of the most important and least understood elements of tropical rainforest ecology. Additionally, data and techniques from this study will help to disentangle the evolutionary and ecological dynamics operating within symbiotic gut communities themselves. These communities have both direct (via diseases like Inflammatory Bowel Disease) and indirect (via association with agricultural pests such as locusts and aphids) impacts on human society, and yet they remain poorly understood. This research will provide training opportunities for students in cutting-edge areas of sequencing and data analysis, and the results will be communicated to the public via ongoing museum- and K12-based outreach activities.