DGGs under positive selection.

a, Numbers of sequences in the listed DGGs.b, Numbers of sequences analyzed in pairwise comparisons. Partial sequences were excluded.c, Highest dN/dS ratio among all pairwise comparisons within one PGG. ∞ refers to pairwise comparisons in which dN>0 and dS = 0. NA means two sequences are the same in one pair.d, Yes indicates sufficient evidence for positive selection if the two likelihood tests (M2a vs. M1a, M8 vs M7) performed show statistical significance.e, Number of PSS identified with posterior probability P>95%.