NOTE 15B: Imagine that a large population is reduced to a much smaller size, so that most variation is lost. Then, the distribution of allele frequencies among the loci that remain polymorphic (a fraction 6p₀q₀e^–t/2Ne) is approximately uniform. This is a quite different prediction from the case when mutation and drift have reached an equilibrium (as in the standard neutral theory) and so can be used to distinguish these alternatives. We will see examples where the distribution of allele frequencies is used in this way in Chapter 19.