Dec 19, 2013

Horizontal gene transfer can rescue prokaryotes from Muller's ratchet: benefit of DNA from dead cells and population subdivision

G3 : Genes - Genomes - Genetics
Nobuto TakeuchiEugene V Koonin

Abstract

Horizontal gene transfer (HGT) is a major factor in the evolution of prokaryotes. An intriguing question is whether HGT is maintained during evolution of prokaryotes owing to its adaptive value or is a byproduct of selection driven by other factors such as consumption of extracellular DNA (eDNA) as a nutrient. One hypothesis posits that HGT can restore genes inactivated by mutations and thereby prevent stochastic, irreversible deterioration of genomes in finite populations known as Muller's ratchet. To examine this hypothesis, we developed a population genetic model of prokaryotes undergoing HGT via homologous recombination. Analysis of this model indicates that HGT can prevent the operation of Muller's ratchet even when the source of transferred genes is eDNA that comes from dead cells and on average carries more deleterious mutations than the DNA of recipient live cells. Moreover, if HGT is sufficiently frequent and eDNA diffusion sufficiently rapid, a subdivided population is shown to be more resistant to Muller's ratchet than an undivided population of an equal overall size. Thus, to maintain genomic information in the face of Muller's ratchet, it is more advantageous to partition individuals into multiple subpopulations an...Continue Reading

  • References70
  • Citations33

References

Mentioned in this Paper

Genome
Extracellular
Archaea
Homologous Recombination
Gene Transfer, Horizontal
Genomics
Recombination, Interspecies
Prokaryote
Cell Death
Homologous Recombination Pathway

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