Streamlining and simplification of microbial genome architecture

Research output: Chapter in Book/Report/Conference proceedingChapter

167 Scopus citations


The genomes of unicellular species, particularly prokaryotes, are greatly reduced in size and simplified in terms of gene structure relative to those of multicellular eukaryotes. Arguments proposed to explain this disparity include selection for metabolic efficiency and elevated rates of deletion in microbes, but the evidence in support of these hypotheses is at best equivocal. An alternative explanation based on fundamental population-genetic principles is proposed here. By increasing the mutational target sizes of associated genes, most forms of nonfunctional DNA are opposed by weak selection. Free-living microbial species have elevated effective population sizes, and the consequent reduction in the power of random genetic drift appears to be sufficient to enable natural selection to inhibit the accumulation of excess DNA. This hypothesis provides a potentially unifying explanation for the continuity in genomic scaling from prokaryotes to multicellular eukaryotes, the divergent patterns of mitochondrial evolution in animals and land plants, and various aspects of genomic modification in microbial endosymbionts.

Original languageEnglish (US)
Title of host publicationAnnual Review of Microbiology
EditorsNicholas Ornston, Albert Balows, Susan Gottesman, Caroline Harwood
Number of pages23
StatePublished - 2006
Externally publishedYes

Publication series

NameAnnual Review of Microbiology
ISSN (Print)0066-4227


  • Genome evolution
  • Genomic streamlining
  • Mutation
  • Prokaryotes
  • Random genetic drift
  • Recombination

ASJC Scopus subject areas

  • Microbiology


Dive into the research topics of 'Streamlining and simplification of microbial genome architecture'. Together they form a unique fingerprint.

Cite this