Table 3. Comparisons of non-synonymous (d_N) and synonymous (d_S) substitutions per site of the MHC class I domains from six frog species.

Species	dN−dS
	α1+α2 PBR	α1+α2 non-PBR	α3
A. callidryas	0.476±0.126a	−0.069±0.018	−0.037±0.027
E. prosoblepon	0.498±0.113a	−0.043±0.019	−0.038±0.020
L. catesbeianus	0.343±0.133	−0.035±0.021	−0.039±0.020
L. clamitans	0.399±0.123a	−0.046±0.024	−0.021±0.014
L. yavapaiensis	0.375±0.096a	0.014±0.016	−0.006±0.014
S. phaeota	0.295±0.089a	−0.011±0.018	−0.004±0.020

^aMean d_N is significantly higher than mean d_S (P<0.05).