Richard Lenski’s experiment is in the news again:
The LTEE required 33,000 generations and many years for the bacteria to acquire the supposedly new trait. In the video Lenski says that one of his lab’s researchers wanted to explore “why did it take so long to evolve this and why has only one population evolved that ability?” The implication is that this is a complex trait that required many slow mutations to arise. Lenski says it was a “difficult” trait to evolve because it required both a “rare mutation” and also a “series of events” where multiple mutations were needed before any advantage was conferred. Van Hofwegen realized there was something fishy about these claims. As he explained to IDTF:
“The only difference is that in the conditions of the [LTEE] experiment, they didn’t have a transporter. They [E. coli bacteria] didn’t have the ability to bring that citrate outside of their cells into the cells and actually use it for energy. And so when I looked at that experiment as a microbiologist I thought, all they have to do is turn that thing on. That’s really easy for bacteria to do. Why did it take them 33,000 generations to do that?”
Van Hofwegen draws a comparison to a light switch. Normal E. coli have the metabolic pathways to live off citrate, and they have the ability to transport it into their cells. But under the conditions of the experiment that “light switch” was turned off. The bacteria didn’t need to evolve a new metabolic pathway or a new transport feature to eat citrate. All they needed to do was turn on their transporter under the oxic conditions of the LTEE experiment. The organisms used the “light switch” to express their citrate transporter. So how did they do it?
A 2016 peer-reviewed study in the Journal of Bacteriology, “Rapid Evolution of Citrate Utilization by Escherichia coli by Direct Selection Requires citT and dctA,” co-authored by Van Hofwegen and biologists Scott Minnich and Carolyn Hovde, has the answer. In their research they witnessed the same trait, the ability to use this “lemony dessert,” arise in under 100 generations and 14 days. This result was repeatable 46 times. They found that the trait is not very genetically complicated — again, akin to flipping a switch — and that there is more to the story than is being been told. Indeed, their paper shows that no new genetic information arose during the evolution of this trait.
Casey Luskin, “Viral Video Overstates the Evidence About Bacterial Evolution” at Evolution News and Science Today
Hey. The Darwinians are marketing magic and it is really difficult to refute magic.
Here’s the vid making the claim: