Evolution in a test tube

The most interesting story of last week for my money is the latest from the Lenski files. One criticism of modern evolutionary theory is that it cant be tested in the lab. Prof Lenski, who back in 1989 started breeding escherichia coli from a single individual under artificial conditions has arguably done just that, as recently evolved populations now have the ability to consume citrate. Given that the inability to eat citrate is one of the defining characteristics of e coli, this is no ordinary mutation. What’s more, the team was able to replay the “speciation event” by thawing out earlier generations and breeding them once more. I recommend the NY times article by Carl Zimmer for the full story. Once again it has been demonstrated that new and adaptive genomic information has been generated by selective pressure acting on the random variation of replicating organisms.