Collaborative Research: Camponotine Ants and their Little Helpers: Phylogenomics of a Hyperdiverse Insect Clade and its Bacterial Endosymbionts (CAnBE)

近年来，人们对与人类有关的微生物产生了极大的好奇和兴趣，尤其是与肠道微生物群的共生关系，这些微生物群对人类健康有益。这种营养共生现象经常发生在许多不同的生物体中，包括灵长类动物、植物和昆虫。这项研究将调查一个非常成功和多样化的昆虫群体，木蚁及其亲戚，以及细菌Blochmannia的共同进化史。木蚁是世界上种类最多、数量最多的蚂蚁，大多数孩子在外面玩耍时都遇到过木蚁。所有木蚁的肠道细胞内都携带布氏杆菌，使这种细菌成为内共生体。这两种生物都依赖彼此生存。有证据表明，木蚁和Blochmannia在数千万年来一直保持着密切的营养伙伴关系。不同种类生物之间的专性共生关系可以深刻地影响伴侣双方的性质和进化速度，并且微生物内共生体已经被认为在某些昆虫类群的多样化中发挥了重要作用。这项研究将确定木蚁及其近亲是如何与Blochmannia一起进化的。这些发现将提高我们对动物共生如何产生和维持的理解，对人类相关微生物系统的进化具有潜在的影响。此外，该项目将强调蚂蚁生物多样性和微生物共生的公众教育，以及对早期职业科学家的培训。本研究将推断Camponotini部落蚂蚁的系统发育、分化时间和生物地理历史，并利用这一比较框架推进其内共生细菌Blochmannia的系统和共同进化研究。像其他专性内共生体一样，与自由生活的细菌相比，Blochmannia表现出大量的基因组减少。基因组进化和Blochmannia的功能变异将通过具有对比形态和生态属性的冠状蚁的系统发育代表性选择进行评估。通过共同阐明蚂蚁和内共生体的进化史，该项目将解决以下问题：(1)横跨Camponotini分支的Blochmannia基因组进化的主要特征是什么？(2) Blochmannia层序演化的过程、速率和模式？(3)麻风病基因含量变异是否与麻风病宿主的特定属性有关？通过将蚂蚁的系统发育和性状数据与细菌的功能基因组特性联系起来，我们将了解这种非凡的共生关系背后的选择力和限制。对冠足蚁的详细系统发育研究也将为这一分类学上被忽视的类群的专题研究奠定坚实的基础，并有助于开发更有效的鉴定工具。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Recent years have seen an explosion of curiosity and interest in the microbial associates of humans, especially symbiotic associations with gut microbiota that convey benefits to human health. Such nutritional symbioses occur frequently across many different organisms, including primates, plants, and insects. This research will investigate the joint evolutionary history of a highly successful and diverse group of insects, carpenter ants and their relatives, and the bacteria Blochmannia. Carpenter ants are the most diverse and abundant group of ants in the world - most kids have encountered them while playing outside. All carpenter ants carry Blochmannia bacteria inside their gut cells, making the bacterium an endosymbiont. Both organisms rely on one another to survive. Evidence indicates that carpenter ants and Blochmannia have maintained a close nutritional partnership for tens of millions of years. Obligate symbiotic associations among different kinds of organisms can profoundly impact the nature and tempo of the evolution of both partners, and microbial endosymbionts have been suggested to have played important roles in the diversification of some insect groups. This research will determine how the carpenter ants and their relatives evolved alongside Blochmannia. The findings will improve our understanding of how symbioses arise and are maintained in animals, with potential implications for the evolution of human-associated microbial systems. Moreover, the project will emphasize public education in ant biodiversity and microbial symbioses, and the training of early-career scientists.This research will infer the phylogeny, divergence times, and biogeographic history of ants in the tribe Camponotini, and use this comparative framework to advance systematic and co-evolutionary studies of their endosymbiotic bacteria Blochmannia. Like other obligate endosymbionts, Blochmannia exhibits substantial genome reduction compared to free-living bacteria. Genome evolution and functional variation in Blochmannia will be evaluated across a phylogenetically representative selection of camponotine ants with contrasting morphological and ecological attributes. By jointly elucidating the ant and endosymbiont evolutionary histories, the project will address such questions as: (1) What are the major features of Blochmannia genome evolution across the Camponotini clade? (2) What processes shape rates and patterns of Blochmannia sequence evolution? (3) Is Blochmannia gene content variation associated with particular camponotine host attributes? By linking phylogenetic and trait data on the ants to functional genomic properties of the bacteria we will gain an understanding of the selective forces and constraints underlying this remarkable symbiosis. A detailed phylogeny of the camponotine ants will also create a strong foundation for much-needed monographic work on this taxonomically neglected group, and allow the development of more effective identification tools.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.