Nov 26, 2009

In the E. coli of the beholder

This paper from Lenski et al (Lenski is famous for his long term study on evolution in the lab of populations of the bacteria Escherichia Coli) in the PNAS has been claimed, in one of those rather annoying internet discussions which I stumbled across, to show a “beneficial mutation”. The paper is a report on what the authors believe is the most significant event of the mega-tastic (my phrase) E. Coli study; i.e. a mutant able to use the compound citrate -pictured- in addition to glucose in respiration. I have no beef with the concept of a beneficial mutation as such; I do though, suspect this paper wasn’t the best example, as it only makes the ‘beneficial mutation’ point rather incidentally and (see point 3 below) a bit ambiguously. I also find it intriguing how people with different backgrounds can draw rather different conclusions from research such as this.
I’ve just flicked through it, but I’m inclined to see support for Michael Behe’s claim’s concerning the statistical difficulty of obtaining traits requiring multiple mutations, while another person brandishes the paper as a near-decisive H-bomb in their personal war against creationists.
Other interesting things:1) The “rapid improvements in fitness” witnessed decelerated over time – of course, we should not be surprised, but some people might be.
2) Simon Conway-Morris was cited favourably – always nice to see
3) The actual mutations involved aren’t yet known at the genetic level – hence it is not known whether the initial point mutation (it appears there were two of these) was selectively advantageous or not.
-There’s probably more stuff, but I’ve got over it for now.

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