image: These Petri dishes contain colonies of two strains of E. coli bacteria that can be tracked by their different colors. By watching the change over time in the relative abundance of the two types, Woods et al. were able to track new beneficial mutations as they arose. This image relates to an article that appeared in the March 18, 2011, issue of Science, published by AAAS. The study, by Dr. Woods, at Michigan State University in East Lansing, Mich., and colleagues was titled, "Second-Order Selection for Evolvability in a Large Escherichia coli Population." view more
Credit: Jeffrey Barrick