title: Ancestral relationships of the major eukaryotic lineages.
abstract: Molecular systematics has revolutionized our understanding of microbial evolution. Phylogenetic frameworks relating all organisms in this biosphere can be inferred from comparisons of slowly evolving molecules such as the small and large subunit ribosomal RNAs. Unlike today's text book standard, the "Five Kingdoms" (plants, animals, fungi, protists and bacteria), molecular studies define three primary lines of descent (Eukaryotes, Eubacteria, and Archaebacteria). Within the Eukaryotes, the "higher" kingdoms (Fungi, Plantae, and Animalia) are joined by at least two novel complex evolutionary assemblages, the "Alveolates" (ciliates, dinoflagellates and apicomplexans) and the "Stramenopiles" (diatoms, oomycetes, labyrinthulids, brown algae and chrysophytes). The separation of these eukaryotic groups (described as the eukaryotic "crown") occurred approximately 10(9) years ago and was preceded by a succession of earlier diverging protist lineages, some as ancient as the separation of the prokaryotic domains. The molecular phylogenies suggest that multiple endosymbiotic events introduced plastids into discrete eukaryotic lineages.
authors.affiliation: Center for Molecular Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA. sogin@evol5.mbl.edu
authors.forename: M L
authors.initials: ML
authors.lastname: Sogin
authors.forename: H G
authors.initials: HG
authors.lastname: Morrison
authors.forename: G
authors.initials: G
authors.lastname: Hinkle
authors.forename: J D
authors.initials: JD
authors.lastname: Silberman
mesh_terms: D000828:Animal Population Groups / Q000145:classification / Q000235:genetics; D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics; D005057:Eukaryotic Cells; D019143:Evolution, Molecular; D005658:Fungi / Q000145:classification / Q000235:genetics; D006801:Humans; D010802:Phylogeny; D010944:Plants / Q000145:classification / Q000235:genetics; D018087:Plastids / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013559:Symbiosis
chemical_list: D012336:RNA, Ribosomal, 16S