Flutterby™! : Evolution in the lab 2008-06-10 22:07:45.837933+00

Evolution in the lab

2008-06-10 22:07:45.837933+00 by Dan Lyke 3 comments

Bacteria make major evolutionary shift in the lab.

Twenty years ago, evolutionary biologist Richard Lenski of Michigan State University in East Lansing, US, took a single Escherichia coli bacterium and used its descendants to found 12 laboratory populations.

One strain develops the ability to metabolize citrate. Because intermediate samples were stored in a freezer, they can go back and replay to figure out where the mutation occurred in that one population.

Lenski's experiment is also yet another poke in the eye for anti-evolutionists, notes Jerry Coyne, an evolutionary biologist at the University of Chicago. "The thing I like most is it says you can get these complex traits evolving by a combination of unlikely events," he says. "That's just what creationists say can't happen."

Via SE.

Oy. I'm reading Greg Bear's Quantico while at WWDC, and I don't need to think more about evolution in single-celled organisms.

Bacterial identification by metabolic processes has been the gold standard since Pasteur, but there have always been atypical strains that will/won't metabolize certain nutrients, can/can't produce them for themselves, or produce particular breakdown products on particular diets. Such changes in these atypical strains are clearly the result of evolutionary processes, as is the acquisition of antibiotic resistances. Such changes can even be predictable enough to form the basis for mutagenicity testing, as in the Ames test using Salmonella typhimurium.

What seems to be particularly interesting in this current work is that in one of the 12 cultural lines, one or more "invisible" changes took place. These changes later set up a higher probability mutation for gaining the use of citrate. The real excitement here I suspect is the ability to create a Markoff chain for these events and to describe their chemistry.

As far as providing fodder for the war against ignorance goes: there is already more than enough corroborating information from geology, biochemistry in addition to the original anatomy and physiology basis, to convince any reasonable person. It doesn't even help to point out that the Laws of chemistry and physics are so intertwined that if evolutionary theory is incorrect, then their cell phones and computers wouldn't work.

Yes, but what you don't know is that those 12 populations of bacteria are all praying to the great god Lenski and thanking him for giving them these nice, citrate-filled worlds in which to live and thrive.