Patterns and rates of nucleotide substitution, insertion and deletion in the endosymbiont of ants Blochmannia floridanus

L. Gómez-Valero, A. Latorre, R. Gil, Juergen Gadau, H. Feldhaar, F. J. Silva

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Genome reduction is a general process that has been studied in numerous symbiotic bacteria associated with insects. We investigated the last stages of genome degradation in Blochmannia floridanus, a mutualistic bacterial endosymbiont of the ant Camponotus floridanus. We determined the tempo (rates of insertion and deletion) and mode (size and number of insertion-deletion events) of the process in the last 200 000 years by analysing a total of 16 intergenic regions in several strains of this endosymbiont from different ant populations. We provide the first calculation of the reduction rate for noncoding DNA in this endosymbiont (2.2 × 10-8 lost nucleotides/site/year) and compare it with the rate of loss in other species. Our results confirm, as it has been observed in other organisms like Buchnera aphidicola or Rickettsia spp., that deletions larger than one nucleotide can still appear in advanced stages of genome reduction and that a substitutional deletion bias exists. However, this bias is not due to a higher proportion of deletion over insertion events but to a few deletion events being larger than the rest. Moreover, we detected a substitutional AT bias that is probably responsible for the increase in the number of the small and moderate indel events in the last stages of genome reduction. Accordingly, we found intrapopulational polymorphisms for the detected microsatellites in contrast to the stability associated with these in free-living bacteria such as Escherichia coli.

Original languageEnglish (US)
Pages (from-to)4382-4392
Number of pages11
JournalMolecular Ecology
Volume17
Issue number19
DOIs
StatePublished - Oct 1 2008

Keywords

  • Blochmannia floridanus
  • Camponotus floridanus
  • Deletional bias
  • Evolution
  • Genome reduction
  • Reduction rate

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics

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