Dimensions: Identifying how the ecological and evolutionary interactions between host and symbiont shape holobiont biodiversity

尽管个体动物长期以来一直被认为是进化的基本单位，但我们现在知道，每种动物实际上都是宿主动物和微生物的相互依赖的集合。这种相互依赖从古至今一直存在。许多动物依靠肠道细菌来处理食物并将必需的营养物质融入宿主自身的组织中。 为了阐明这种伙伴关系对宿主和共生肠道细菌的重要性，该项目将研究一种多样化且具有生态重要性的社会动物群体——龟蚁。 作为社会有机体，蚂蚁和人类共享获取有益和有害细菌的方法。 最先进的分子和基因组方法将用于研究古代和现代对共生的影响、细菌对宿主健康的功能，以及细菌共生体数百万年来的传代和维持方式。解释全球生物多样性模式及其驱动因素长期以来一直是生态学和进化领域的核心挑战。 越来越明显的是，生物多样性本身就是不同层次的生物组织之间相互作用的函数。 在后生动物中，与微生物的共生是一个决定性的特征，个体是宿主细胞和共生细胞的整合集合，共同定义了“全生物”。 通过研究多样化且易于驯服的龟蚁系统，这项研究将以前所未有的清晰度解决共生与全生物生物多样性维度之间的关系。 具体来说，本研究将解决：1）时间、生物地理学和栖息地在宿主多样化（宿主分类维度）中的作用； 2）宿主蚂蚁系统发育、地理、栖息地和生态位之间肠道群落的变化（共生分类维度与宿主分类和功能维度的整合）； 3）〜10个核心、宿主特异性共生体谱系的共同多样化程度，以及宿主系统发育、地理和生态学对共生体转移的影响（共生体分类维度与宿主分类和功能维度相结合）； 4）具有不同程度共同多样化的共生体之间以及具有不同功能（宿主和共生体的分类学、遗传和功能整合）的基因之间的基因组进化和创新的变化； 5）根据共生体基因组进化、宿主-共生体共同多样化以及宿主系统发育、地理和生态学（宿主和共生体的分类学、遗传和功能整合）来确定共生体功能。

Although individual animals have long been considered a fundamental unit of evolution, we now know that each is really a co-dependent collection of host animal and microbes. This co-dependency reaches from ancient times through to the present day. Many animals depend on gut bacteria to process food and incorporate essential nutrients into the host's own tissues. To untangle the importance of this partnership for hosts and symbiotic gut bacteria, this project will study a diverse and ecologically important social animal group, the turtle ants. As social organisms, ants and humans share ways for acquiring helpful and harmful bacteria. State-of-the-art molecular and genomic methods will be used to investigate ancient and modern influences on the symbiosis, the function of the bacteria for host health, and the means of passage and maintenance of the bacterial symbionts over millions of years.Explaining global patterns of biodiversity and their drivers have long been central challenges in the fields of ecology and evolution. Increasingly, it is becoming apparent that biodiversity is itself a function of interactions across different levels of biological organization. Among the metazoans, symbioses with microbes are a defining feature, and individuals are integrated collections of host and symbiont cells, together defining the "holobiont". By studying the diverse and tractable turtle ant system, this research will address the relationships between symbiosis and the dimensions of holobiont biodiversity with unprecedented clarity. Specifically, this research will address: 1) the roles of time, biogeography, and habitat in host diversification (host taxonomic dimension); 2) variation in gut communities across host ant phylogeny, geography, habitat, and ecological niches (symbiont taxonomic dimension integrated with host taxonomic and functional dimensions); 3) the extent of codiversification for ~10 core, host-specific symbiont lineages, and the impacts of host phylogeny, geography, and ecology on symbiont transfer (symbiont taxonomic dimension integrated with host taxonomic and functional dimensions); 4) variation in genome evolution and innovation across symbionts with varying degrees of codiversification, and across genes with varying function (taxonomic, genetic, and functional integration of hosts and symbionts); and 5) symbiont function in light of symbiont genome evolution, host-symbiont codiversification, and host phylogeny, geography, and ecology (taxonomic, genetic, and functional integration of hosts and symbionts).