RUI: Collaborative Research: The impact of symbiont-larval interactions on species distributions across southwestern Pacific hydrothermal vents

与微生物的共生是普遍存在的，对基本的生物功能如发育和营养至关重要。因此，宿主动物的成功可能取决于其寻找并与其微生物伴侣结合的能力。虽然有些宿主直接将其共生体从亲本传递给后代以保证这一点，但从环境中获得微生物共生体对于许多专性共生动物的生存至关重要。了解自由生活的共生体种群以及宿主如何获得这些共生体是我们理解所有生态系统中生态过程的基础，但几乎一无所知。热液喷口生态系统为研究微生物共生体在宿主、群落和生态系统一级生态中的作用提供了重要机会，因为这些生态系统由动物主导，动物的生存显然与获得一种或几种特定的共生体有关。该项目开始填补我们对热液喷口社区结构驱动因素的理解空白，解决自由生活的共生体种群影响宿主动物建立的潜力，同时扩大我们对宿主相关微生物对适用于整个生态系统的基本生态过程的影响的一般知识。该项目的成果将通过教育视频和现场直播分享给史密森学会国家自然历史博物馆和大学运营的博物馆。调查人员还将设计和实施一个适合初中和高中班级的关于共生和热液喷口生物学的教育方案。最后，研究人员将培训一组不同的本科生和研究生在研究和科学教育计划的发展。该项目将侧重于蜗牛的两个姐妹属，Alviniconcha和Ifremeria，它们主要分布在太平洋西南部的喷口。在劳盆地（汤加）的喷口，三种Alviniconcha和一种Ifremeria共存。这四个物种都主机不同谱系的化能自养变形菌在他们的鳃组织作为成年人，提供他们的大部分营养。以前在这一地区的工作表明，结构化的蜗牛物种分布，对应于共生体化能自养代谢的关键化学底物的浓度，这表明蜗牛物种分类到地球化学栖息地的基础上共生体生理。目前尚不清楚这种分类是否发生在已建立的蜗牛-细菌共生体中，或者环境对特定共生体的影响是否影响宿主物种的招募，因为到达和发育的蜗牛幼虫必须从环境中获得共生体。本研究的目的是：1）通过收集幼虫，少年和成年蜗牛来评估共生喷口蜗牛的幼虫供应和种群结构，2）通过显微镜和配子，幼虫和少年的标记基因测序来调查共生体获取的发育时间，以及3）使用宏基因组测序来量化环境中自由生活的共生体到达幼虫的可用性。总而言之，这一系列相互关联的努力将使人们更好地了解自由生活的细菌共生体种群，共生体收购的时间，和宿主蜗牛的生活史，以及这些东西如何相互作用，以塑造喷口community.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Symbiosis with microbes is ubiquitous and critical to fundamental biological functions such as development and nutrition. Thus, the success of a host animal may depend on its ability to find and associate with its microbial partner(s). While some hosts directly transmit their symbionts from parent to offspring in order to guarantee this, acquisition of microbial symbionts from the environment is vital for the survival of many obligately-symbiotic animals. An understanding of the free-living symbiont population and how the host acquires those symbionts is fundamental to our comprehension of ecological processes in all ecosystems, yet almost nothing is known about either. Hydrothermal vent ecosystems provide important opportunities to investigate the role of microbial symbionts in host-, community-, and ecosystem-level ecology, since these ecosystems are dominated by animals whose survival is clearly linked to the acquisition of one or a few specific symbionts. This project begins to fill a gap in our understanding of the factors driving community structure at hydrothermal vents by addressing the potential for free-living symbiont populations to affect host animal establishment, while also expanding our general knowledge regarding the impact of host-associated microbes on fundamental ecological processes that apply across ecosystems. The results of this project will be shared via educational videos and live-broadcasts to the Smithsonian Institution's National Museum of Natural History and University-run museums. The investigators will also design and implement an educational program about symbiosis and hydrothermal vent biology suitable for middle and high school classes. Finally, the investigators will train a diverse group of undergraduate and graduate students in both research and the development of science educational programs. This project will focus on two sister genera of snails, Alviniconcha and Ifremeria, which predominate at vents in the southwestern Pacific. At vents in the Lau Basin (Tonga), three species of Alviniconcha and one species of Ifremeria coexist. These four species all host distinct lineages of chemoautotrophic proteobacteria in their gill tissue as adults that provide the bulk of their nutrition. Previous work in this region showed a structured snail species distribution that corresponds to the concentrations of key chemical substrates for symbiont chemoautotrophic metabolism, suggesting that snail species are sorting into geochemical habitats based on symbiont physiology. It is not clear if this sorting is occurring among established snail-bacteria symbioses, or whether environmental effects on the availability of specific symbionts are influencing the recruitment of host species, since arriving and developing snail larvae must obtain their symbionts from the environment. This study aims to 1) assess the larval supply and population structure of symbiotic vent snails via collections of larval, juvenile, and adult snails, 2) investigate the developmental timing of symbiont acquisition through microscopy and marker gene sequencing of gametes, larvae, and juveniles, and 3) use metagenomic sequencing to quantify the availability of free-living symbionts in the environment to arriving larvae. Altogether, this series of interlinked efforts will allow for an improved understanding of free-living bacterial symbiont populations, the timing of symbiont acquisition, and host snail life history, as well as how these things interact to shape vent communities.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.