I'm not wanting to start a discussion on evolution or anything of the sort. I am reading "The Greatest Show on Earth" by Richard Dawkins. In it he describes an experiment run by Dr. Richard Lenski and his students. There is an account of it on
Wikipedia.
In the experiment Dr. Lenski and his students started a long term experiment with e. coli bacteria. They set up 12 flasks of sterile water with nutrients and seeded them with the bacteria. Then every day they started 12 new flasks and seeded them with samples from the previous days flasks. They have been doing this since 1988. They track how well the bacteria do in each generation. During that time the bacteria in the various flasks have shown some adaptive changes that enabled them to do better than the initial population. Each day the bacteria multiply until they use up all of the main nutrient, primarily glucose, and then stop. Over time all 12 of the flasks showed increases in the number of total bacteria at the end of the day. However, some flasks did better than others. Apparently there were several strategies that the bacteria could use to improve survival rates and different lines adopted different strategies.
One line did something different though. It went along about with the others for a long time (around 30,000 generations) and then suddenly took off and had an enormous increase in the final population density. When they investigated it seems that the line had suddenly acquired the ability to metabolize citrate, which was also present among the nutrients. Normally e. coli. cannot metabolize citrates. So this was major evolutionary change.
I thought the whole experiment was fascinating. Day after day changing out the flasks and keeping the lines carefully segregated so that they could verify just what happened in each line. It is amazing what some scientists will do.
Bill Gill
