Collaborative Research: RUI: Keystone molecules and estuarine foodwebs: chemical defense and a novel biosynthetic pathway in a common mudflat mollusc

河口是许多经济上重要的沿海物种的生态敏感的苗圃栖息地。对于迁徙的水鸟、幼鱼和各种无脊椎动物捕食者来说，一种潜在的重要但未被充分研究的食物资源是小型海懒(Alderia属)，它可以密集聚集在整个北半球温带泥滩上，每平方米超过1000只。我们假设Alderia使用最近发现的新陈代谢分支来制造味道不佳的分子，称为聚酮，这是一系列化合物，包括医学上重要的药物。我们将从这些丰富的鼻涕虫中鉴定新的聚酮，测试它们如何击退捕食者，然后探索它们可能如何影响生态系统的许多其他方面。这些鼻涕虫化合物的潜在影响包括通过抗生素作用改变泥浆中的细菌；在吸引其他动物物种的同时排斥生活在泥浆中的一些动物物种；以及在泥滩上共同出现的可口的轮状动物中导致模仿鼻涕虫的进化。这些研究将提供新的见解，了解能量如何在河口的食物链中流动，以及一个物种如何对其生态系统中的许多周围物种产生意想不到的影响。我们还将研究气候变化如何改变美国西海岸鼻涕虫物种(以及它们的化合物)的分布，这些物种可能会对受威胁河口的居民产生连锁但以前未被认识到的影响。最后，该项目将支持两所小学本科生之间的合作，其中一所是西班牙裔服务机构和一家大型研究机构，通过这三所学校之间的合作，每年许多本科生和硕士学生将得到该项目的支持。该项目将侧重于招募历来在科学领域任职人数不足的学生参加拟议的研究和外联活动。我们将测试海参产生的聚酮(PK)化合物是否作为Keystone分子发挥作用，改变北半球河口的能量流动和群落结构。泥滩上的小型海懒(Alderia)异常丰富(每平方米1000只)，是各种鱼类、鸟类和无脊椎动物消费者的潜在资源。我们将描述一条生物合成途径和由鼻涕虫产生的新的PK代谢物，并结合实验室和野外提取物和纯化合物的测试来确定PKs是否保护Alderia免受湿地捕食者的侵害。然后，我们将估计由于这种化学防御而导致的初级生产到更高营养水平的净损失。在美国西海岸引进的等足目动物中，巴特斯拟态的快速进化将在这个系统中进行评估，以了解化学防御和视觉捕食如何在短时间尺度上影响共存生物的表型进化。操纵性实验将测试PKS对泥滩微生物群落和非动物群的影响，以确定棚室化合物对这一敏感苗圃生境中不同生态过程的影响。这些研究将从基因到生态系统，研究在普通温带软体动物中作为抗捕食者防御而合成的潜在Keystone化合物的影响。模拟研究将探索范围限制的基础，以及正在进行的气候变化对两个Alderia物种之间范围边界变化的影响。这些结果将共同为全球变化如何改变Keystone分子的分布提供新的见解，从而对已经受到威胁的栖息地(如河口)的群落产生意想不到的影响。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Estuaries are ecologically sensitive nursery habitat for many economically important coastal species. A potentially important but understudied food resource for migratory waterbirds, juvenile fish, and diverse invertebrate predators are small sea slugs (genus Alderia), which can occur in dense aggregations of over 1,000 slugs per square meter on temperate mudflats throughout the Northern Hemisphere. We hypothesize that Alderia use a recently discovered branch of metabolism to make bad-tasting molecules termed polyketides, a family of compounds that include medically important drugs. We will characterize new polyketides from these abundant slugs, test how they repel predators, and then explore how they may affect many other aspects of the ecosystem. Potential effects of these slug compounds include changing the bacteria in the mud through antibiotic effects; repelling some animal species that live in the mud while attracting others; and causing the evolution of slug mimicry in palatable ‘roly-polies’ that co-occur on the mudflat. These studies will provide new insight into how energy moves through the food-chain in estuaries, and how one species can have unexpected effects on many surrounding species in its ecosystem. We will also study how climate change has altered the distribution of slug species (and hence their compounds) along the U.S. west coast, which may have cascading but previously unrecognized effects on the inhabitants of threatened estuaries. Finally, the project will support the collaboration between two primary undergraduate institutions, one of which is Hispanic serving and a large research institution, via the collaboration between the three school many undergraduate and master’s students will be supported each year by the project. The project will focus on the recruitment of students historically underrepresented in science to the proposed research and outreach activities. We will test whether polyketide (PK) compounds produced by sea slugs function as keystone molecules, altering energy flow and community structure in Northern Hemisphere estuaries. Small sea slugs (Alderia) are exceptionally abundant (1000/m2) on mudflats, representing a potential resource for diverse fish, bird and invertebrate consumers. We will characterize a biosynthetic pathway and novel PK metabolites produced by slugs, and determine if PKs protect Alderia from wetland predators using a combination of laboratory and field assays with extracts and pure compounds. We will then estimate the net loss of primary production to higher trophic levels due to this chemical defense. The rapid evolution of Batesian mimicry in introduced isopods along the U.S. west coast will be assessed in this system to understand how chemical defense and visual predation affect phenotypic evolution of co-occuring organisms over short timescales. Manipulative experiments will test the effects of PKs on the microbiome and infaunal community of mudflats to determine the impact of shed compounds on diverse ecological processes in this sensitive nursery habitat. These studies will address, from gene to ecosystem, the impacts of potential keystone compounds synthesized as an antipredator defense in a common temperate mollusc. Modeling studies will explore the basis for range limits and the effects of ongoing climate change on shifting range boundaries between two Alderia species. These results will collectively provide new insight into how global change may alter the distribution of keystone molecules and thus have unanticipated effects on communities in already-threatened habitats such as estuaries.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.