title: Strict cospeciation of devescovinid flagellates and Bacteroidales ectosymbionts in the gut of dry-wood termites (Kalotermitidae).
abstract: The surface of many termite gut flagellates is colonized with a dense layer of bacteria, yet little is known about the evolutionary relationships of such ectosymbionts and their hosts. Here we investigated the molecular phylogenies of devescovinid flagellates (Devescovina spp.) and their symbionts from a wide range of dry-wood termites (Kalotermitidae). From species-pure flagellate suspensions isolated with micropipettes, we obtained SSU rRNA gene sequences of symbionts and host. Phylogenetic analysis showed that the Devescovina spp. present in many species of Kalotermitidae form a monophyletic group, which includes also the unique devescovinid flagellate Caduceia versatilis. All members of this group were consistently associated with a distinct lineage of Bacteroidales, whose location on the cell surface was confirmed by fluorescence in situ hybridization. The well-supported congruence of the phylogenies of devescovinids and their ectosymbionts documents a strict cospeciation. In contrast, the endosymbionts of the same flagellates ('Endomicrobia') were clearly polyphyletic and must have been acquired independently by horizontal transfer from other flagellate lineages. Also the Bacteroidales ectosymbionts of Oxymonas flagellates present in several Kalotermitidae belonged to several distantly related lines of descent, underscoring the general perception that the evolutionary history of flagellate-bacteria symbioses in the termite gut is complex.
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Department of Biogeochemistry, Karl-von-Frisch-Straße, 35043 Marburg, Germany.
authors.forename: Mahesh S
authors.initials: MS
authors.lastname: Desai
authors.forename: Jürgen F H
authors.initials: JF
authors.lastname: Strassert
authors.forename: Katja
authors.initials: K
authors.lastname: Meuser
authors.forename: Horst
authors.initials: H
authors.lastname: Hertel
authors.forename: Wakako
authors.initials: W
authors.lastname: Ikeda-Ohtsubo
authors.forename: Renate
authors.initials: R
authors.lastname: Radek
authors.forename: Andreas
authors.initials: A
authors.lastname: Brune
mesh_terms: D000818:Animals; D041963:Bacteroidetes / Q000145:classification* / Q000235:genetics; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D041981:Gastrointestinal Tract / Q000382:microbiology; D020459:Genes, rRNA; D049810:Genetic Speciation; D017404:In Situ Hybridization, Fluorescence; D020049:Isoptera / Q000382:microbiology*; D008969:Molecular Sequence Data; D056900:Parabasalidea / Q000145:classification* / Q000235:genetics / Q000382:microbiology / Q000648:ultrastructure; D010802:Phylogeny; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D016054:DNA, Protozoan