title: 50 million years of genomic stasis in endosymbiotic bacteria.
abstract: Comparison of two fully sequenced genomes of Buchnera aphidicola, the obligate endosymbionts of aphids, reveals the most extreme genome stability to date: no chromosome rearrangements or gene acquisitions have occurred in the past 50 to 70 million years, despite substantial sequence evolution and the inactivation and loss of individual genes. In contrast, the genomes of their closest free-living relatives, Escherichia coli and Salmonella spp., are more than 2000-fold more labile in content and gene order. The genomic stasis of B. aphidicola, likely attributable to the loss of phages, repeated sequences, and recA, indicates that B. aphidicola is no longer a source of ecological innovation for its hosts.
authors.affiliation: Department of Molecular Evolution, Evolutionary Biology Center, University of Uppsala, Uppsala, Sweden.
authors.forename: Ivica
authors.initials: I
authors.lastname: Tamas
authors.forename: Lisa
authors.initials: L
authors.lastname: Klasson
authors.forename: Björn
authors.initials: B
authors.lastname: Canbäck
authors.forename: A Kristina
authors.initials: AK
authors.lastname: Näslund
authors.forename: Ann-Sofie
authors.initials: AS
authors.lastname: Eriksson
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Wernegreen
authors.forename: Jonas P
authors.initials: JP
authors.lastname: Sandström
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Moran
authors.forename: Siv G E
authors.initials: SG
authors.lastname: Andersson
mesh_terms: D000818:Animals; D001042:Aphids / Q000382:microbiology* / Q000502:physiology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D005075:Biological Evolution; D020635:Buchnera / Q000235:genetics* / Q000502:physiology; D021901:DNA, Intergenic; D004032:Diet; D017753:Ecosystem; D004926:Escherichia coli / Q000235:genetics; D019143:Evolution, Molecular; D005798:Genes, Bacterial; D014644:Genetic Variation; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D011544:Pseudogenes; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D012486:Salmonella typhimurium / Q000235:genetics; D013045:Species Specificity; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D021901:DNA, Intergenic