In the race of life, better an adaptable tortoise than a fit hare

In the study, led by Robert J. Woods, M.D., Ph.D., currently a house officer at the University of Michigan Health System, researchers show that more adaptable bacteria oriented toward long-term improvement prevailed over competitors that held a short-term advantage. Woods completed the work while at Michigan State University pursuing his doctorate.

The result that the less-fit organisms overtook their in-shape counterparts surprised the researchers at first. But it turns out to work something like a game of chess.

“In games it makes sense to sacrifice some pieces for an eventual winning move,” explains senior study author Richard Lenski, MSU Hannah Distinguished Professor of Microbiology and Molecular Genetics. “The eventual winners were able to overcome their short-term disadvantage over the course of several evolutionary moves by producing more beneficial mutations.”

By replaying evolution over and over with the clones, the researchers showed that the eventual winners likely prevailed because they had greater potential for further adaptation.

“In essence, the eventual loser lineage seems to have made a mutational move that gave it a short-term fitness advantage but closed off certain routes for later improvement,” Lenski explains. “And the dead-end strategy allowed the eventual winners to catch up and eventually surpass the eventual losers.”

So, yes, sometimes the tortoise really does beat the hare.

Woods and Lenski’s collaborators include Jeffrey Barrick, a Lenski lab researcher now on the faculty at the University of Texas; Tim Cooper from the University of Houston; MSU undergraduate student Mark Kauth; and University of Houston student Utpala Shrestha.

While Darwin’s theory of natural selection has been confirmed by a great deal of other research, it has never before been observed directly for so many generations and in such detail as Lenski’s long-term experiment has afforded. Lenski’s research is supported by the National Science Foundation, the Defense Advanced Research Projects Agency and by MSU’s AgBioResearch.

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