Similar, and even identical, mutations underlie the metabolic diversification of independently evolving populations of the bacterium Escherichia coli.

Matthew Herron and Michael Doebeli at the University of British Columbia in Vancouver, Canada, exposed E. coli to a mixture of glucose and acetate and found that competition for the carbon sources caused the bacteria, over about 1,200 generations, to evolve into two ecologically and metabolically different strains. This occurred in three independent evolution experiments. The authors sequenced the genomes of the three bacterial populations at 16 points during their evolution. They found many similar and a few identical mutations that underlay the evolution of diversity in the three experiments.

The findings suggest that this evolution is a predictable process that is driven by natural selection.

PLoS Biol. 11, e1001490 (2013)