CAREER: Coevolutionary Community Dynamics of Symbiotic Nitrogen Fixing Associations

我们世界上的一切都被复杂的微生物群落所覆盖，这些微生物群落被称为微生物组。这些微生物群对人类健康、清洁环境和高产作物都很重要。由于它们比宿主小得多，微生物的进化速度要快得多。在微生物组中，一些理论模型预测，更快的进化将导致导致更严重疾病的微生物，而其他模型预测，更快的进化将导致有益微生物变得更加有益。了解这些结果发生的时间对于提出管理微生物组的策略非常重要。该项目将使用共同进化理论模型来了解在三叶草植物根部定居的微生物群落是如何相互作用和进化的。三叶草是许多农作物的近亲，如豆类、苜蓿和鹰嘴豆，这些信息可以用来提高农业产量和土壤健康。学生将学习研究这些微生物的方法，并将分离菌株，分析基因组和生理学，并测量生态相互作用。该项目将在太平洋西北地区招募服务不足的美国原住民学生。这个项目还将制作一个共同进化的视频游戏，将推广和教育与研究结合起来。将学生研究人员、经验主义者和理论家聚集在一起的研讨会将促进这一快速发展领域的变革性研究。宿主相关微生物群落是宿主性状和生态系统过程的关键媒介，了解这些群落在自然界中如何相互作用和共同进化是一个科学前沿。三叶草结节相关微生物群落是研究这些过程的理想模型系统。这个项目有三个关键要素：(1)在Bodega Bay建立一个可访问的现场系统，可以收集宿主和相关微生物的长期数据；(2)能够将关键参与者带到实验室，测量宿主-微生物和微生物-微生物相互作用的分子基础，评估适应度协方差模式，并进行实验共同进化；(3)可以用经验数据参数化的数学模型，以预测群落组装和共同进化动力学。该项目将探讨(1)进化速率的不对称如何影响复杂群落中的共同进化；(2)“红皇后”动态——对抗者之间的军备竞赛——超过“红王”动态的情景，其中快速进化的互惠主义者进化出代价高昂的特征，以增强宿主的适应性；(3)多方互动如何影响宿主的利益和专业化。通过将不同进化时间尺度上的经验测量与数学模型联系起来，该项目将有可能深入了解复杂的共同进化宿主相关群落的一般特性。该奖项反映了美国国家科学基金会的法定使命，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。

Everything in our world is covered in complex communities of microorganisms called microbiomes. These microbiomes are important for human health, clean environments, and productive crops. Since they are much smaller than their hosts, microorganisms can evolve much faster. Within the microbiomes, some theoretical models predict that faster evolution will result in microorganisms that cause more severe disease, whereas other models predict that faster evolution will cause beneficial microorganisms to become even more beneficial. Understanding when each of these outcomes occurs will be important for coming up with strategies to manage microbiomes. This project will use coevolutionary theoretical models to understand how communities of microorganisms that colonize the roots of clover plants interact and evolve. Clover is a relative of many crop plants such as beans, alfalfa, and chickpeas, and this information can be used to improve agricultural yield and soil health. Students will be trained in methods to study these microorganisms and will isolate strains, analyze genomes and physiology, and measure ecological interactions. The project will recruit underserved Native American students in the Pacific Northwest. This project will also produce a coevolutionary video game that will combine outreach and education with research. A symposium bringing together student researchers, empiricists, and theoreticians will catalyze transformative research in this rapidly moving field.Host-associated microbial communities are key mediators of host traits and ecosystem processes, and a scientific frontier is understanding how these communities interact and coevolve in nature. Clover nodule-associated microorganismal communities are an ideal model system to study these processes. This project has three key elements: (1) an accessible field system at Bodega Bay, amenable to the collection of long-term data on both hosts and associated microorganisms, (2) the ability to bring key players into the lab to measure the molecular basis of host-microorganism and microorganism-microorganism interactions, assess patterns of fitness covariance, and conduct experimental coevolution, and (3) mathematical models that can be parameterized with empirical data to predict community assembly and coevolutionary dynamics. The project will address (1) how asymmetries in evolutionary rates influence coevolution in complex communities, (2) scenarios in which 'Red Queen' dynamics–arms races between antagonists–outpace 'Red King' dynamics, where rapidly-evolving mutualists evolve costly traits that enhance host fitness, and (3) how multi-partite interactions influence host benefit and specialization. By linking empirical measurements over varying evolutionary timescales to mathematical models, this project will potentially generate insight into general properties of complex coevolving host-associated 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.