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 (www.mbl.edu/microscope) will be expanded to include educational materials at multiple levels.
