title: Bacterial recombination promotes the evolution of multi-drug-resistance in functionally diverse populations.
abstract: Bacterial recombination is believed to be a major factor explaining the prevalence of multi-drug-resistance (MDR) among pathogenic bacteria. Despite extensive evidence for exchange of resistance genes from retrospective sequence analyses, experimental evidence for the evolutionary benefits of bacterial recombination is scarce. We compared the evolution of MDR between populations of Acinetobacter baylyi in which we manipulated both the recombination rate and the initial diversity of strains with resistance to single drugs. In populations lacking recombination, the initial presence of multiple strains resistant to different antibiotics inhibits the evolution of MDR. However, in populations with recombination, the inhibitory effect of standing diversity is alleviated and MDR evolves rapidly. Moreover, only the presence of DNA harbouring resistance genes promotes the evolution of resistance, ruling out other proposed benefits for recombination. Together, these results provide direct evidence for the fitness benefits of bacterial recombination and show that this occurs by mitigation of functional interference between genotypes resistant to single antibiotics. Although analogous to previously described mechanisms of clonal interference among alternative beneficial mutations, our results actually highlight a different mechanism by which interactions among co-occurring strains determine the benefits of recombination for bacterial evolution.
authors: Division of Biology, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK. gperron@fas.harvard.edu
authors: Gabriel G
authors: GG
authors: Perron
authors: Alexander E G
authors: AE
authors: Lee
authors: Yun
authors: Y
authors: Wang
authors: Wei E
authors: WE
authors: Huang
authors: Timothy G
authors: TG
authors: Barraclough
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000737:chemistry; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D014644:Genetic Variation; D011995:Recombination, Genetic
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial