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

河口是生态敏感的苗圃栖息地，许多重要的经济沿海物种。小型海蛞蝓（Alderia属）是迁徙水鸟、幼鱼和各种无脊椎动物捕食者的一种潜在重要但研究不足的食物资源，在整个北方半球的温带泥滩上，这种海蛞蝓每平方米可密集聚集超过1，000只。我们假设Alderia使用最近发现的代谢分支来制造称为聚酮化合物的味道不好的分子，这是一种包括医学上重要药物的化合物家族。我们将从这些丰富的鼻涕虫中描述新的聚酮化合物，测试它们如何击退捕食者，然后探索它们如何影响生态系统的许多其他方面。这些蛞蝓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;排斥一些生活在泥浆中的动物物种，同时吸引其他动物;并导致蛞蝓模仿在泥滩上共同出现的美味“roly-polies”中的进化。这些研究将为能源如何在河口的食物链中移动提供新的见解，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了鼻涕虫物种的分布（因此它们的化合物）沿着美国西海岸，这可能对受威胁的河口的居民产生级联但以前未被认识的影响。最后，该项目将支持两个主要本科院校之间的合作，其中一个是西班牙裔服务和一个大型研究机构，通过三所学校之间的合作，许多本科生和硕士生每年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代表性不足的学生参加拟议的研究和外联活动。我们将测试海蛞蝓产生的聚酮化合物（PK）是否起关键分子的作用，改变北方河口的能量流和群落结构。小海蛞蝓（Alderia）在泥滩上异常丰富（1000/m2），是各种鱼类，鸟类和无脊椎动物消费者的潜在资源。我们将表征生物合成途径和新的PK代谢产物产生的蛞蝓，并确定如果PK保护Alderia从湿地捕食者使用提取物和纯化合物的实验室和现场试验相结合。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级的净损失。在这个系统中，将评估沿着美国西海岸引进的等足类动物中的Baeridae拟态的快速进化，以了解化学防御和视觉捕食如何在短时间内影响共存生物的表型进化。操纵实验将测试PKs对泥滩微生物组和底栖动物群落的影响，以确定棚化合物对这个敏感的苗圃栖息地的不同生态过程的影响。这些研究将解决，从基因到生态系统，潜在的关键化合物合成作为一种常见的温带软体动物的抗捕食防御的影响。模拟研究将探讨范围限制的基础和持续的气候变化对两个Alderia物种之间变化范围边界的影响。这些结果将共同为全球变化如何改变关键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）的社区产生意想不到的影响。该奖项反映了NSF的法定使命，并被认为值得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来支持。

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.