Phylogenetic niche conservatism as a driver of microbial diversification and biogeography

链霉菌属的细菌在土壤中分布广泛且常见。它们在碳循环中发挥着重要作用，是发现抗生素和其他天然产物的主要来源。超过一半的临床抗生素是在该属中首次发现的，但该属仍然缺乏一个强大的分类框架。更令人吃惊的是，几乎完全没有关于链霉菌生物多样性和植物地理学的信息。抗生素耐药性的演变是一个关键问题，也是一个日益严重的危机。解决这一危机既需要努力鉴定新型抗生素，也需要努力对抗耐药菌株的进化。了解链霉菌的进化历史将最终提供对抗生素生产和耐药性的进化动力学的见解。虽然具有重要的社会价值，但对链霉菌等非致病性土壤生物的生物地理学和进化史的研究却不够深入。了解链霉菌的遗传学和促进其进化多样化的机制，应刺激发现新的遗传多样性和新的生物活性化合物的自然种群。本计画将探讨链霉菌属土壤细菌微生物群落学模式的生态与演化力量。主要假设是链霉菌表现出纬度梯度的多样性所造成的冰川后的范围扩张在北方纬度加上扩散限制，由于系统发育生态位保守。这一假设将通过（1）使用高通量测序方法和计算分析来表征北美的链霉菌属植物地理学特征和（2）对来自纬度上定义的姐妹分类群的菌株进行基因组和生理学分析来检验。这个项目是转型，因为它探讨了一个新的模式，了解陆地微生物的地理和多样化。此外，通过研究姐妹类群及其最近共同祖先菌株中的微生物基因组动态，作为其进化历史，地理和栖息地的函数，该项目将揭示选择和水平基因转移对基因和生物体遗传的作用的基本原理。

Bacteria in the genus Streptomyces are widespread and common in soils. They have important roles in the carbon cycle, and they are a major source for the discovery of antibiotics and other natural products. More than half of clinical antibiotics were first discovered within this genus, yet the genus still lacks a robust taxonomic framework. Even more striking, there is nearly a complete absence of information about Streptomyces biodiversity and biogeography. The evolution of antibiotic resistance is a critical concern and a growing crisis. Addressing this crisis requires both efforts to identify novel antibiotics and efforts to combat the evolution of resistant strains. Understanding the evolutionary history of Streptomyces will ultimately provide insight on the evolutionary dynamics of antibiotic production and resistance. While of critical societal value, research on the biogeography and evolutionary history of non-pathogenic soil organisms such as Streptomyces is understudied. An understanding of the biogeography of Streptomyces and mechanisms that promote their evolutionary diversification should stimulate discovery of novel genetic diversity and new bioactive compounds from natural populations. This project will examine the ecological and evolutionary forces that underlie patterns of microbial biogeography for soil bacteria in the genus Streptomyces. The main hypothesis is that Streptomyces exhibit a latitudinal gradient of diversity caused by post-glacial range expansion in northern latitudes coupled with dispersal limitation due to phylogenetic niche conservatism. This hypothesis will be tested by (1) using a high-throughput sequencing approach and computational analyses to characterize Streptomyces biogeography in North America and (2) performing genomic and physiological analysis of strains from latitudinally defined sister-taxa. This project is transformational in that it examines a new paradigm for understanding the biogeography and diversification of terrestrial microorganisms. Furthermore, by examining microbial genome dynamics in stains of sister-taxa and their most recent common ancestors as a function of their evolutionary history, geography, and habitat, this project will reveal fundamental principles on the role of selection and horizontal gene transfer on gene and organismal phylogenies.