Co-author of E. coli paper dodges questions
A co-author of that paper, Zachary Blount, has been dodging some simple, basic questions I have asked about it.
I originally thought that the purpose of growing the E. coli bacteria with lots of citrate and an insufficient glucose supply was to try to promote the evolution of citrate-eating mutants by giving them an advantage over bacteria that can only eat glucose. Carl Zimmer wrote in a blog article titled "A New Step in Evolution":
The experiment was launched by MSU biologist Richard Lenski . . . Lenski started off with a single microbe. It divided a few times into identical clones, from which Lenski started 12 colonies. He kept each of these 12 lines in its own flask. Each day he and his colleagues provided the bacteria with a little glucose, which was gobbled up by the afternoon. The next morning, the scientists took a small sample from each flask and put it in a new one with fresh glucose. And on and on and on, for 20 years and running.
However, in the comment thread under the article, Zachary Blount has been making mutually contradictory statements about whether an original purpose of the experiment was to try to evolve citrate-eating (Cit+) E. coli bacteria:
When Dr. Lenski started, he figured the citrate would provide an opportunity that the populations might or might not figure out a way to exploit, thereby presenting a potential point of divergence between the populations (this is my understanding -- I will need to check with him to make certain I understand this properly). (comment #115)
the intent of the experiment was never to evolve a Cit+ E. coli variant (comment #115)
The evolution of a citrate-utilizing variant E. coli was seen from the beginning as a possible occurrence, and one that would be pretty neat should it occur (and indeed as it has proven to be now that it has happened), but not a goal. (emphasis added) (comment #122)
I tried to get Blount to either poop or get off the can -- was evolving a Cit+ variant a goal (or a hoped-for result or a wished-for result or whatever) of the experiment or not? I also asked him to describe the purpose of the insufficient glucose supply if the purpose was not to try to promote evolution of a Cit+ variant. He dodged the questions, telling me to just read the literature. When the co-author of a scientific paper refuses to give direct, consistent answers to simple, basic questions about the paper, that paper has no credibility.