:If the Cit+ change required a single mutation with a low but constant probability over time one would expect Cit+ mutations to be distributed across cells taken from any generation of the experiment. On the other hand, if a 'potentiating' mutation had to arise at some point in the cultures before the final Cit+ mutation could function, then one would expect the probability for Cit- cells to mutate to Cit+ cells would increase with samples of cells taken from later cultures. | :If the Cit+ change required a single mutation with a low but constant probability over time one would expect Cit+ mutations to be distributed across cells taken from any generation of the experiment. On the other hand, if a 'potentiating' mutation had to arise at some point in the cultures before the final Cit+ mutation could function, then one would expect the probability for Cit- cells to mutate to Cit+ cells would increase with samples of cells taken from later cultures. |