Table 1.

Likelihood ratio tests of seven different site models performed on 296 amino acids (888 bp) of the HSP 40 kDa, including 29 of the 32 unique alleles (A11, A12 and A18 were excluded from the analysis, as they only occurred in specimens affected by hybridization/introgression).

Site model	LRT	2∆l	df	p-value	l	ω	BEBs
M0 (one-ratio)	M0 vs. M3	262.398852	4	<< 0.001	− 3598.034542	0.0718	–
M3 (discrete)					− 3466.835116	0.1439
M1a (nearly Neutral)	M1a vs. M2a	11.558380	2	0.003	− 3480.993265	0.1328	–
M2a (positive selection)					− 3475.214075	0.1815
M7 (β)	M7 vs. M8	21.480488	2	<< 0.001	− 3477.904393	0.1108	–
M8 (β & ω)					− 3467.164149	0.1450
M8a (β & ω = 1)	M8a vs. M8	31.89007	1	<< 0.001	− 3483.109184	0.0769	10*; 38*; 249**; 256*; 286*; 292**

Underlying phylogeny is based on the ITS1 (532 bp) of B. calyciflorus s.s., B. fernandoi, B. angularis, B. diversicornis and B. rubens. For each likelihood ratio test (LRT), we provide log likelihood (l) values of the compared tests (2∆l), degrees of freedom (df), p-values, estimated average ratio of non-synonymous vs. synonymous substitutions (ω), and the sites inferred to be under positive selection by Bayes Empirical Bayes (BEB) analysis, labeled with an * for a posterior probability of > 95% and ** for > 99%.