50 million years of genomic stasis in endosymbiotic bacteria

Science. 2002 Jun 28;296(5577):2376-9. doi: 10.1126/science.1071278.


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.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Aphids / microbiology*
  • Aphids / physiology
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Biological Evolution
  • Buchnera / genetics*
  • Buchnera / physiology
  • DNA, Intergenic
  • Diet
  • Ecosystem
  • Escherichia coli / genetics
  • Evolution, Molecular*
  • Genes, Bacterial
  • Genetic Variation
  • Genome, Bacterial*
  • Molecular Sequence Data
  • Mutation
  • Operon
  • Pseudogenes
  • Recombination, Genetic
  • Repetitive Sequences, Nucleic Acid
  • Salmonella typhimurium / genetics
  • Species Specificity
  • Symbiosis*


  • Bacterial Proteins
  • DNA, Intergenic

Associated data

  • GENBANK/AE013218