I saw this post about human population diversity the other day...and though it was interesting, there was something that stuck in my craw:
Actually, this will be sharper for genes under selection, since selection should be weaker in bottleneck populations.
I don't think this is true. Selection isn't weaker, random genetic drift is stronger. Consider the probability of fixation of a new mutation. If the mutation is neutral so selection is non-existent its frequency is being buffeted only by random genetic drift. As you probably know, the probability of fixation is 1/(2Ne), where Ne is the effective breeding population. So if a neutral mutant arises in a population of 10 in one of the individuals, it has a 1 out of 10 shot at fixation (with an expectation of fixation in 40 generations, that is 4Ne). If the effective population is 1000 the probability of fixation is 1 out of ...
