Understanding the Diversity and Biology of Microbes in Late Paleozoic Ecosystems

微生物，包括细菌、蓝藻、微藻以及各种真菌和类似真菌的生物(如孢子菌)，是当今所有群落的重要组成部分。这些生物在过去当然发挥着类似的功能，并在从分解到营养循环的一系列活动中对古代生态系统的进化和可持续性负责。然而，不幸的是，关于微生物个体群体在过去的地质历史中究竟是如何发挥作用的，人们知之甚少。在这项研究计划中，将对早泥盆世至晚石炭世硅质岩中三维保存的各种微生物进行调查。泥盆纪和石炭纪是地质时代的重要时期，所有主要的陆地维管植物(被子植物除外)谱系及其身体平面的基本建筑原则(如根、枝轴、叶)都在进化。由于植物多样性的增加，生态上独特的(微型)生境的数量急剧增加，这反过来又导致了新的和特定的植物-微生物相互作用的进化(例如，叶片内生作用)。由于微生物和它们的宿主都保存在硅质岩中，这些组合提供了一个非同寻常的机会，通过重要的地质时期记录微生物的多样性，并研究在古代陆地生态系统功能中至关重要的一些复杂的相互作用。其中一些相互作用包括寄生、腐生和不同程度的互惠关系。为了实现这一研究议程的目标，组建了一个拥有化石和现存微生物专业知识的国际团队。该项目将包括四个相互关联的主题：1)记录整个微生物多样性，2)通过已知寄主植物的地质时间段检查多样性，3)根据现有的肾菌根真菌所使用的孢子壁特征来表征某些类型的互惠(菌根)真菌，4)根据寄主反应记录微生物的相互作用。利用结构保存的生物是直接研究各种微生物与其化石宿主之间存在的复杂相互作用的唯一方法。记录这些微生物、它们的相互关系以及与其他生物的相互作用将使追踪共同进化趋势成为可能，这些共同进化趋势可以与现代方法一起用于研究维持和驱动陆地生态系统的某些类型生物和生态过程的进化史。

Microorganisms, including bacteria, cyanobacteria, microalgae, and various fungi and fungal-like organisms (e.g., Peronsporomycetes), are critical components of all communities today. These organisms certainly performed similar functions in the past, and were responsible for the evolution and sustainability of ancient ecosystems in activities ranging from decomposition to nutrient cycling. Unfortunately, however, relatively little is known about how precisely the individual groups of microorganisms functioned in the geologic past. In this research program, various microorganisms that are three-dimensionally preserved in Early Devonian to Late Carboniferous cherts will be investigated. The Devonian and Carboniferous are important periods of geologic time in which all major lineages of vascular land plants (except angiosperms) and the fundamental architectural principles of their body plan (e.g., roots, shoot axis, leaves) evolved. As a result of this increased plant diversity, the number of ecologically distinct (micro-) habitats increased drastically, which, in turn, has resulted in the evolution of new and specific plant-microbe interactions (e.g., leaf endophytism). Because both microbes and their hosts are preserved in chert, these associations provide an extraordinary opportunity to document the diversity of microbes through an important segment of geologic time, and also to study a number of complex interactions that were critical in the functioning of the ancient terrestrial ecosystems. Some of these interactions include parasitism, saprophytism, and various degrees of mutualistic association. To accomplish the goals of this research agenda an international team was assembled that has expertise with both fossil and extant microbes. The project will encompass four interrelated themes: 1) documenting overall microbe diversity, 2) examining diversity through segments of geologic time in which there are well known host plants, 3) characterizing certain types of mutualistic (mycorrhizal) fungi based on spore wall features used with extant glomeromycoytan fungi, 4) documenting microbe interactions based on host responses. The utilization of structurally preserved organisms is the only method available to directly investigate complex interactions that existed between various microbes and their fossil hosts. Documenting these microorganisms, their associations, and interactions with other organisms will make it possible to trace co-evolutionary trends that can be used together with modern approaches to investigate the evolutionary history of certain types of biological and ecological processes that sustain and drive terrestrial ecosystems.