Data from: Epistasis and allele specificity in the emergence of a stable polymorphism in Escherichia coli

Ecological opportunities promote population divergence into coexisting
lineages. However, the genetic mechanisms that enable new lineages to
exploit these opportunities are poorly understood except in cases of
single mutations. We examined how two Escherichia coli lineages diverged
from their common ancestor at the outset of a long-term coexistence. By
sequencing genomes and reconstructing the genetic history of one lineage,
we showed that three mutations together were sufficient to produce the
frequency-dependent fitness effects that allowed this lineage to invade
and stably coexist with the other. These mutations all affected regulatory
genes and collectively caused substantial metabolic changes. Moreover, the
particular derived alleles were critical for the initial divergence and
invasion, indicating that the establishment of this polymorphism depended
on specific epistatic interactions.