Epistasis and Allele Specificity in the Emergence of a Stable Polymorphism in Escherichia coli

Abstract

Serial Mutation Mutations that affect gene function and, ultimately, the phenotype of an organism are grist to the mill of evolution. While examining the genetic basis for a stable polymorphism observed in bacteria during a long-term mutation experiment, Plucain et al. (p. 1366 , published online 6 March) identified three specific, successive mutational events exhibiting synergistic epistatic and frequency-dependent interactions that enabled one lineage to invade the other and to be maintained. Thus, a series of specific mutations conferred the invasion phenotype and allowed the use of novel resources only when all mutations were present.