Fu and Li's test
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Test for gene selection or demographic changes in population. Tajima's test is based on the fact that under the neutral model estimates of the number of segregating/polymorphic sites and of the average number of nucleotide differences are correlated. If the value of D is too large or too small, the neutral 'null' hypothesis is rejected. DnaSP calculates the D and its confidence limits (two-tailed test). Tajima did not base this test on coalescent but Fu and Li's tests (Fu & Li, 1993) are directly based on coalescent. The tests statistics D and F require data from intraspecific polymorphism and from an outgroup (a sequence from a related species), and D* and F* only require intraspecific data. DnaSP uses the critical values obtained by Fu & Li, 1993, to determine the statistical significance of D, F, D* and F* test statistics. The results of this group of tests (Tajima's D and Fu & Li's tests) based on allelic variation and/or level of variability may not clearly distinguish between selection and demographic alternatives (bottleneck, population subdivision) but this problem only applies to the analysis of a single locus (demographic changes affect all loci whereas selection is expected to be locus-specific which are distinguishable if multiple loci are analyzed). (http://dorakmt.tripod.com/evolution/popgen.html)
