Mitchell Sogin

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Groups

Marine Biological Laboratory
- MBL Bay Paul Center

Research Focus

The Sogin laboratory employs comparative phylogenetic studies of genes and genomes to define patterns of evolution that gave rise to contemporary biodiversity. We are especially interested in discerning how the eukaryotic cell was invented as well as the identity of microbial groups that were ancestral to animals, plants, and fungi. Phylogenetic inferences based upon comparisons of ribosomal RNAs have discovered new evolutionary assemblages that are as genetically diverse and complex as plants, fungi, and animals. The nearly simultaneous separation of these eukaryotic groups (described as the eukaryotic "Crown") occurred approximately one billion years ago and was preceded by a succession of earlier diverging protist lineages. The basal eukaryotic lineages may be older than once thought possible; given the amitochondriate phenotype of early-diverging lineages, the presence of oxygen is not prerequisite to forming a nucleus. We are now using a combination of whole genome sequence analyses (Giardia lamblia and Nosema locustae) and large scale cDNA sequencing projects for as many as thirty different protists to explore genome diversity in ancestral eukaryotes. These data will provide a description of what came early in the evolution of nuclear genomes and will identify alternative genes for inferring phylogenetic relationships.