TABLE 2.

Analysis of positive selection in vacA using the McDonald-Kreitman testa

• a The neutrality index (NI) was calculated from the ratio of the number of polymorphisms to the number of substitutions as follows: NI = (Pn/Ps)/(Dn/Ds), where P is polymorphic within the population, D is divergence or fixed difference between populations, n is nonsynonymous, and s is synonymous. Shaded lines indicate statistically significant results that are indicative of positive selection. NA, not applicable.

• b Group 1, m1 non-Asian; group 2, ml Asian; group 3, m2.

• c The proportion of adaptive substitutions that ranges from −∞ to 1 and is estimated as 1 − NI.