Collaborative Research: Linking carbon preferences and competition to predict and test patterns of functional diversity in soil microbial communities

该项目将发展理论，以了解生物多样性和有限资源竞争之间的联系。竞争是所有生物体之间重要的相互作用。例如，植物与其他植物竞争光和营养资源，而动物则竞争食物和领土。由于资源有限，竞争在所难免。这种限制限制了物种共存的能力，因此寻求了解生物多样性的科学家也必须了解竞争。竞争理论表明，竞争物种只能通过专注于不同的资源而共存。然而，这不能解释物种数量超过资源的多样性社区的存在。该项目将探索不同社区中的物种可能成功共享资源的理论可能性。该项目将发展理论，以测试当社区包含具有高度相似特征但集群之间高度不相似的物种集群时是否会出现共存。重点将是土壤微生物群落，这是地球上最多样化的。土壤微生物竞争碳分子，这是它们的主要能源和生物量。这项研究将量化这些相互作用如何影响这些微生物的共存能力。鉴于微生物在营养循环中的重要作用以及温度变化对竞争关系的可能影响，这项研究将使生态学家能够预测加速环境变化的后果。此外，该项目将培训和指导研究生和本科生，并制作一个互动的在线应用程序，学生将学习如何在社区规模的生物多样性模式的个人之间的竞争。该研究建立在现有的消费者资源微生物模型，以开发一个基于性状的土壤细菌多物种竞争模型。该模型将假设碳源具有自然流入和降解速率，而微生物种群从移民和温度依赖的资源吸收中增长，并具有固定的死亡率。每个物种都有自己的可用碳源库，当它吸收这些资源时，产生的副产品可能是其他物种库的一部分（交叉喂养）。这些方法包括计算机模拟、统计推断和高维空间中的聚类分析。将检验的中心假设是：a）竞争动态加上扩散导致几个共存物种联合体的自发出现，使得同一集群中的物种在碳偏好上具有高度重叠，而不同集群中的物种在碳偏好上具有低重叠; B）环境条件和扩散制度决定集群的数量和物种组成。这些假设得到了以下结果的支持：竞争是微生物群落中的一个重要过程，以及在动物、植物和浮游植物竞争驱动的群落中观察到的类似聚类模式。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。

This project will develop theory to understand the connections between biodiversity and competition for limiting resources. Competition is an important interaction among all living organisms. For example, plants compete with other plants for light and nutrient resources, while animals compete for food and territories. Because resources are limited, competition is unavoidable. This limitation constrains the ability of species to coexist together, so scientists seeking to understand biodiversity must also understand competition. Competition theory suggests that competing species can only coexist by specializing on different resources. However, this cannot explain the existence of diverse communities where species outnumber the resources. This project will explore the theoretical possibility that species in diverse communities may successfully share resources. The project will develop theory to test if coexistence occurs when communities contain clusters of species with highly similar traits but high dissimilarity among clusters. The focus will be on soil microbial communities, which are among the most diverse on Earth. Soil microbes compete for carbon molecules, which are their main source of energy and biomass. The research will quantify how these interactions affect those microbes’ ability to coexist. Given the important role that microbes play in nutrient cycling and the likely impacts that temperature changes have on competitive relationships, this research will allow ecologists to predict the consequences of accelerated environmental change. Additionally, this project will train and mentor graduate and undergraduate students and produce an interactive online app where students will learn how competition among individuals creates patterns of biodiversity at the community scale.The research builds on existing consumer-resource microbial models to develop a trait-based multispecies competition model for soil bacteria. The model will assume that carbon sources have natural inflow and degradation rates while microbe populations grow from immigration and temperature-dependent resource uptake and have a fixed mortality rate. Each species will have its own repertoire of usable carbon sources and, as it uptakes those resources, produces byproducts which may be part of other species’ repertoires (cross-feeding). The approaches include computer simulations, statistical inference, and clustering analysis in high-dimensional spaces. The central hypotheses that will be tested are a) competitive dynamics coupled with dispersal leads to the spontaneous emergence of several co-occurring consortia of species, such that species in the same cluster have high overlap in carbon preferences, whereas species in different clusters have low overlap in carbon preferences; b) environmental conditions and dispersal regimes determine the number and species composition of the clusters. These hypotheses are supported by results showing that competition is an important process in microbial communities and by the observation of analogous clustering patterns in competition-driven communities of animals, plants, and phytoplankton.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.