TABLE 2.

Log likelihood values and estimated parameters under models in PAML^a

Model	lnL	2ΔlnL	P value	Estimated parameter(s)	Positive selection sites
M0	−5,972.703			ω = 0.344
M1a	−5,868.144			p0 = 0.667, p1 = 0.333 ω0 = 0.085, ω1 = 1
M2a	−5,863.300	9.687	<0.01	p0 = 0.662, p1 = 0.331, p2 = 0.007 ω0 = 0.086, ω1 = 1, ω2 = 4.526	K157, A351
M7	−5,868.087			p = 0.237, q = 0.430
M8	−5,862.086	12.002	<0.005	p0 = 0.991, p = 0.252, q = 0.469 p1 = 0.009, ω = 3.784	K157, A351

^aTwo pairs of site models with CODEML implemented in the PAML v 4.8 were performed. The first pair involves M1a (neutral, 2 site classes, ω > 1 not allowed) versus M2a (selection, 3 site classes, ω > 1 allowed), and the second pair consists of M7 (neutral, 10 site classes, ω > 1 not allowed) versus M8 (selection, 11 site classes, ω > 1 allowed). lnL, log likelihood.