CAREER: Coevolutionary Community Dynamics of Symbiotic Nitrogen Fixing Associations

我们世界上的一切都被称为微生物群的复杂微生物群落所覆盖。这些微生物群对人类健康、清洁环境和高产作物都很重要。因为微生物比它们的宿主小得多，所以微生物可以进化得更快。在微生物群中，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，而另一些模型预测，更快的进化将使有益的微生物变得更有益。了解每一种结果发生的时间对于制定管理微生物群的战略将是重要的。这个项目将使用共同进化理论模型来理解定居在三叶草植物根部的微生物群落如何相互作用和进化。三叶草是豆类、紫花苜蓿和鹰嘴豆等许多农作物的近亲，这些信息可以用来提高农业产量和土壤健康。学生将接受研究这些微生物的方法培训，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部招募服务不足的美洲原住民学生。该项目还将制作一款共同进化的视频游戏，将推广和教育与研究结合起来。一场将学生研究人员、经验学家和理论家聚集在一起的研讨会将催化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特征和生态系统过程的关键中介，而科学前沿是了解这些群落在自然界中如何相互作用和共同进化。三叶草根瘤相关微生物群落是研究这些过程的理想模式系统。该项目有三个关键要素：(1)博德加湾可访问的田野系统，适合收集关于宿主和相关微生物的长期数据；(2)能够将关键参与者带入实验室，以测量宿主-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，并进行实验性共同进化；以及(3)可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。该项目将解决(1)进化速度的不对称如何影响复杂群落中的共同进化，(2)“红皇后”动态--对手之间的军备竞赛--超过“红王”动态的情景，其中快速进化的互助者进化出提高宿主适应性的昂贵特征，以及(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范围内的经验测量与数学模型联系起来，该项目将潜在地洞察复杂的共同进化宿主相关社区的一般属性。该奖项反映了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。

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.