Fu and Li’'s test 


Fu and Li’'s test search for term

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)