A test of neutrality and constant population size based on the mismatch distribution.

Several factors including demographic changes, selection, and recombination are known to affect the distribution of the number of pairwise differences between DNA sequences. The effects of each of these forces have previously been used to estimate population parameter values using various assumptions about other factors. In this article, we use the predictions of the mismatch distribution under a standard neutral equilibrium model to design a coalescent simulation-based test and detect any deviation from this equilibrium. When reliable independent estimates are available for the intragenic recombination rate, this test can be used as a neutrality test or a population expansion test in actual studies, under reasonable assumptions.