  Here, it will be noticed, the focus is not on the generation of variations but on the perpetuation of variations.  The contrast is between a random sampling of gametes that leads to the fixation of selectively neutral alleles and natural selection favoring advantageous variations.  That is, the contrast between ‘chance’ and ‘fitness biased’ processes is now being used to distinguish different means of perpetuating certain variations. We are contrasting two sampling processes. Drift samples without concern for adaptation; selection samples discriminately on the basis of differences in fitness. Both samplings are ‘probabilistic’, of course, but that in no way obviates the above contrast.