Collaborative Research: Investigations into microbially mediated ecological diversification in sponges

珊瑚礁是一个矛盾的现象，因为尽管它们具有巨大的生产力和生物多样性，但它们却位于相当于“海洋沙漠”的营养贫乏的栖息地。“高度生物多样性往往与资源的划分有关，这种划分允许许多类型的生物以最小的竞争共存。事实上，与珊瑚礁上的许多其他生物不同，海绵适合通过过滤进食有效地去除海水中的细菌，浮游植物和溶解的有机物。海绵是全世界和加勒比地区珊瑚礁的主要组成部分，其生物量超过造礁珊瑚。近四分之一世纪以来，海绵在加勒比海的成功一直与它们的滤食能力有关。然而，最近的工作表明，加勒比海珊瑚礁上共存的海绵拥有独特的细菌群落，这可能使海绵能够获得其他生物无法获得的多种营养物质。在这个项目中，研究人员将测试这样一个假设，即加勒比海的生态优势海绵物种具有独特的代谢策略，这些策略是由它们与生活在海绵体内的微生物的联系介导的。这项研究将结合联合收割机操纵现场实验与现代分析工具的新组合，以调查海绵宿主的滤食及其微生物的代谢途径。 这项工作将促进我们对生态和进化力量的理解，这些力量帮助塑造了加勒比珊瑚礁上的物种。此外，该项目将支持三名早期职业调查员，并为诺瓦东南大学、阿巴拉契亚州立大学、斯托尼布鲁克大学和史密森尼海洋站的研究生和本科生提供培训机会。研究人员还将制定创新的外展计划，扩大其机构的现有平台，以提高公众参与和科学素养。在加勒比，海洋海绵在扩大其生态范围方面取得了广泛成功，其生物量往往超过造礁珊瑚，物种多样性也很高。 然而，这一成功是否与有效的异养过滤器在水柱中的有机碳喂养或其在微生物共生体的进化投资尚未完全阐明。微生物共生体扩大了宿主海绵的代谢能力，补充无机碳和氮的异养喂养，调解溶解的有机物质的同化，并促进宿主来源的氮的再循环。 尽管有这些好处，微生物共生体社区在共存的海绵物种之间存在很大差异，并且宿主海绵对共生体来源的碳和氮的依赖存在很大差异;因此，这些协会可能介导共存海绵物种的生态多样化。该项目的目标是通过采用综合方法评估全生物代谢的各个组成部分（即，微生物共生体和海绵宿主）在加勒比海最常见的十种海绵物种中。研究人员将分离自养和异养代谢途径，并探索微生物共生体群落组成与海水中颗粒物和溶解有机物（POM和DOM）同化之间的潜在联系。该项目将阐明加勒比海海绵物种是否处于相似或不同的进化轨迹上，并将提供对我们了解加勒比海盆地的条件如何塑造底栖生物进化至关重要的信息。该奖项反映了NSF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。

Coral reefs represent a paradox because, despite their immense productivity and biodiversity, they are found in nutrient-poor habitats that are equivalent to "marine deserts." High biodiversity is often associated with a division of resources that allows many types of organisms to coexist with minimal competition. Indeed, unlike many other organisms on coral reefs, sponges are adapted to efficiently remove bacteria, phytoplankton, and dissolved organic matter from seawater by filter-feeding. Sponges are a dominant component of coral reefs worldwide and in the Caribbean, where their biomass exceeds that of reef-building corals. For almost a quarter century, the success of sponges in the Caribbean has been linked to their filter-feeding ability. However, recent work demonstrated that coexisting sponges on Caribbean reefs host unique communities of bacteria that might allow sponges to access multiple pools of nutrients that are not available to other organisms. In this project, the investigators will test the hypothesis that ecologically dominant sponge species in the Caribbean have unique metabolic strategies that are mediated by their associations with microbes that live within the sponge body. This research will combine manipulative field experiments with a novel combination of modern analytical tools to investigate both filter-feeding by sponge hosts and the metabolic pathways of their microbes. This work will advance our understanding of the ecological and evolutionary forces that have helped shape the species present on Caribbean coral reefs. Additionally, this project will support three early-career investigators and provide training opportunities for graduate and undergraduate students at Nova Southeastern University, Appalachian State University, Stony Brook University, and Smithsonian Marine Station. The investigators will also develop innovative outreach programs that expand existing platforms at their institutions to increase public engagement and scientific literacy. Marine sponges have been widely successful in their expansion across ecological niches in the Caribbean, with biomass often exceeding that of reef-building corals and high species diversity. However, whether this success is linked to efficient heterotrophic filter-feeding on organic carbon in the water column or to their evolutionary investment in microbial symbionts is yet to be fully elucidated. Microbial symbionts expand the metabolic capabilities of host sponges, supplementing heterotrophic feeding with inorganic carbon and nitrogen, mediating the assimilation of dissolved organic matter, and facilitating recycling of host-derived nitrogen. Despite these benefits, microbial symbiont communities are widely divergent across coexisting sponge species and there is substantial variation in host reliance on symbiont-derived carbon and nitrogen among host sponges; therefore, these associations likely mediate the ecological diversification of coexisting sponge species. The goal of this project is to test this transformative hypothesis by adopting an integrative approach to assess the individual components of holobiont metabolism (i.e., microbial symbionts and sponge host) in ten of the most common sponge species in the Caribbean. The investigators will isolate autotrophic and heterotrophic metabolic pathways and explore potential links between microbial symbiont community composition and the assimilation of particulate and dissolved organic matter (POM and DOM) from seawater. This project will elucidate whether Caribbean sponge species are on similar or divergent evolutionary trajectories, and will provide information that is critical for our understanding of how conditions in the Caribbean basin have shaped the evolution of benthic organisms.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.