I don't know where your number comes from, but the approach does not work.All valid points....I am still intrigued, in reference to the E.coli evolution experiment, about the odds of the Citrate + ( mutation resulting in E.coli that are able to utilize Citrate in aerobic conditions) occurring. There are 4288 genes found to be coding for proteins in E.coli (see https://en.wikipedia.org/wiki/Escherichia_coli#Genomics). If we conservatively estimate that it requires 2 potentiating mutations to allow for a final actuating mutation to develop, which then results in a new trait (such as the Citrate utilizing protein), then the number of potential mutations would be described by the permutation formula. C representing the maximum number of possible combinations and n the total subjects in a field, r the number of subsets, thus based on the formula C = n!/ (r! ( n-r )! ), we arrive at 13,131,343,936 possible combinations/ mutations! The Citrate + mutation seems to have developed very early in the total pathway of the C number of possible mutations. How did that happen?!! by anyones understanding of this?
If the mutation indeed occurred early on, then the implications are as prior noted.
If conversely, the mutation occurred in the latter part of the mutation spectrum, then this too has implications. Namely, that the E.coli are still very phenotypically recognizable as the progenitor E.coli. i.e., they have not evolved into something in any way unrecognizable from the original.
Well, yes but realistically....one can say still understand that probability wise, an early onset Cit + mutation has remarkable implications.Or, if it did indeed occur 'early', it could simply have been due to plain old probability. An event with a one-in-a-million chance of happening can certainly occur the first time. People win the lottery every day.
I don't see how the mutations occurring 'later' as apposed to 'earlier' has anything to do with whether or not the bacteria have evolved into something beyond the original species.
Assuming only three mutations underestimates the probability massively.Yes, the study references 2 potentiating mutations and 1 actualizing mutation leading to the Cit+ phenotype, and the estimate number of total potential mutations, utilizing the permutation formula, may actually be a very conservative one with the r or subset number, being 3 only.
The question is an important one. Perhaps someone very familiar with the intricacies of the E.coli evolution study can add to this? If the mutation indeed occurred early on, then the implications are as prior noted. If conversely, the mutation occurred in the latter part of the mutation spectrum, then this too has implications. Namely, that the E.coli are still very phenotypically recognizable as the progenitor E.coli. i.e., they have not evolved into something in any way unrecognizable from the original.
Ok but the question remains, where in the spectrum of all of the possible mutations (let us call this the X amount) did the Citrate +[set] of mutations occur? [If] it was earlier on (in this pathway of total possible mutations), then it stretches probability theory for such a beneficial trait to emerge in the time that it did. It was mentioned by Drakkith earlier that it would be analogous to winning the lottery.All the bacteria accumulated many mutations. Mutations that don't change fitness can easily stay in the pool, so you always have a huge amount of different DNA sets in the sample.
I understand with more clarity your point.The experiment had way more cells, so even a much smaller number of mutations is sufficient to get a reasonable chance of three mutations at specific places.
The culture conditions for the LTEE are fairly close to optimal growth conditions for an organism like E. coli.
I don't see any indication that it would have occured very early or very late. Estimating the probability precisely looks like a huge challenge.Ok but the question remains, where in the spectrum of all of the possible mutations (let us call this the X amount) did the Citrate +[set] of mutations occur? [If] it was earlier on (in this pathway of total possible mutations), then it stretches probability theory for such a beneficial trait to emerge in the time that it did. It was mentioned by Drakkith earlier that it would be analogous to winning the lottery.
So, with regards to the E.coli evolution experiment, would modifying the culture medium of the E.coli change it from, as noted earlier, a purifying selection process to a diversifying one? If the E.coli were placed in a more natural environment with amplified survival pressure, could we expect diversification of E.coli phenotypes?I don't see any indication that it would have occured very early or very late. Estimating the probability precisely looks like a huge challenge.
So the different kinds of environments could be: varied temperatures, light/dark exposure, pH variances, tepid versus turbulent environments (that which would simulate wave action, for example) and variations in nutrients and base chemistries. This would mimic conditions found in nature.
