Lenski experiment bacterial body size in one tribe

You can see that most of the increase in body size occurred in the first 2,000 or so generations. The next interesting question is this. Given that all twelve tribes increased in body size over evolutionary time, did they all increase in the same way, by the same genetic route? No, they didn't, and that's the second interesting result. The graph at the top of page 123 is for one of the twelve tribes. Now look at the equivalent hyperbolic best fits for all twelve (graph at the foot of page 123). Look how spread out they are. They all seem to be approaching a plateau, but the highest of the twelve plateaus is almost twice as high as the lowest. And the curves have different shapes: the curve that reaches the highest value by generation 10,000 starts by growing more slowly than some of the others, and then overtakes them before generation 7,000. Don't confuse these plateaus, by the way, with the daily plateaus of population size within each flask. We are now looking at curves in evolutionary time, measured in flask generations, not individual bacterial time, measured in hours within one flask.

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