AToL: Collaborative Research: Reconstructing Eukaryotic Phylogeny through Multigene Analyses of Microbial Eukaryotes

要真正了解地球上的生物多样性，就需要把微生物正确地放在生命之树上。地球上的生命以两种形式存在：(1)原核生物（细菌和古细菌），它们都是微生物；(2)真核生物，有细胞核的细胞。真核生物本身在我们更熟悉的肉眼可见的真核生物群体（植物、动物和真菌）进化之前的大约10亿年里都是纯微生物。微生物真核生物，或原生生物，具有巨大的细胞多样性，并在生态系统中发挥重要作用（如海洋系统中的碳固定）。此外，一些微生物真核生物是影响许多国家社会和经济命运的流行传染病（例如疟疾）的病原体。这个合作项目是美国国家科学基金会资助的“组装生命之树”项目的一部分，将通过分析来自200种主要自由生活的原生生物的9个基因的DNA序列来阐明真核生物之间的关系。对结果数据的分析将把现有的系统发育方法与为本项目开发的方法结合起来。这些分析对于：1)统一包括原核生物和真核生物的普遍生命树，2)理解多细胞真核生物的多重起源，以及3)解释致病原生生物的起源至关重要。这项研究将为美国的原生生物研究注入活力，同时回答有关真核生物生命之树的基本问题。至少有三名博士后和三名研究生将被纳入拟议的研究。本科生也将在研究的各个方面接受培训，主要研究人员将继续致力于从传统上代表性不足的群体中招募学生。该项目还包括发展一个关于原生生物收集和鉴定（通过光学显微镜）的讲习班。最后，探索真核生物多样性的网络工具micro*scope （http://www.mbl.edu/microscope）将扩展到包括多个层次的教育材料。

To truly understand biological diversity on Earth requires that microorganisms be correctly placed on the Tree of Life. Life on Earth exists in two forms: (1) prokaryotes (Bacteria and Archaea), all of which are microbial, and (2) eukaryotes, cells with nuclei. Eukaryotes themselves were exclusively microbial for about one billion years before the evolution of the more familiar macroscopic eukaryotic groups: plants, animals, and fungi. Microbial eukaryotes, or protists, are characterized by tremendous cellular diversity and play an essential role in ecosystems (e.g. carbon fixation in marine systems). Moreover, some microbial eukaryotes are the causative agents of prevalent infectious diseases (e.g. malaria) that impact the social and economic fortunes of many countries. This collaborative project, part of the NSF-funded effort "Assembling the Tree of Life" will elucidate relationships among eukaryotes by analyzing DNA sequences of nine genes from 200 species of predominantly free-living protists. Analyses of the resulting data will combine existing phylogenetic approaches with those developed for this project. These analyses are essential for: 1) unifying the universal tree of life that includes both prokaryotes and eukaryotes, 2) understanding the multiple origins of multicellular eukaryotes, and 3) interpreting the origins of disease-causing protists. The study will invigorate protist research in the U.S. while answering fundamental questions about the eukaryotic Tree of Life. At least three postdoctoral fellows and three graduate students will be integrated into the proposed research. Undergraduates will also be trained in all aspects of the research, and the principal investigators will maintain their commitment to recruiting students from traditionally underrepresented groups. The project also includes the development of a workshop on collection and identification (by light microscopy) of protists. Finally, micro*scope, a web-based tool for exploring eukaryotic diversity (http://www.mbl.edu/microscope) will be expanded to include educational materials at multiple levels.