Relaxed natural selection alone does not permit transposable element expansion within 4,000 generations in Escherichia coli.

ABSTRACT: Insertion sequences (ISs) are transposable genetic elements in bacterial genomes. IS elements are common among bacteria but are generally rare within free-living species, probably because of the negative fitness effects they have on their hosts. Conversely, ISs frequently proliferate in intracellular symbionts and pathogens that recently transitioned from a free-living lifestyle. IS elements can profoundly influence the genomic evolution of their bacterial hosts, although it is unknown why they often expand in intracellular bacteria. We designed a laboratory evolution experiment with Escherichia coli K-12 to test the hypotheses that IS elements often expand in intracellular bacteria because of relaxed natural selection due to (1) their generally small effective population sizes (N (e)) and

SUBMITTER: Plague GR 

PROVIDER: S-EPMC3163157 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature