STATISTICAL TESTS OF NEUTRALITY OF MUTATIONS AGAINST POPULATION-GROWTH, HITCHHIKING AND BACKGROUND SELECTION

The main purpose of this article is to present several new statistical tests of neutrality of mutations against a class of alternative model s, under which DNA polymorphisms tend to exhibit excesses of rare alle les or young mutations. Another purpose is to study the powers of exis ting and newly developed tests and to examine the detailed pattern of polymorphisms under population growth, genetic hitchhiking and backgro und selection. It is found that the polymorphic patterns in a DNA samp le under logistic population growth and genetic hitchhiking are very s imilar and that one of the newly developed tests, F-S, is considerably more powerful than existing tests for rejecting the hypothesis of neu trality of mutations. Background selection gives rise to quite differe nt polymorphic patterns than does logistic population growth or geneti c hitchhiking, although all of them show excesses of rare alleles or y oung mutations. We show that Fu and Li's tests are among the most powe rful tests against background selection. Implications of these results are discussed.