Table 2.

Nonsynonymous (dN) and synonymous (dS) substitutions (± SE from 5000 bootstraps) as well as their ratio in ABS and non-ABS based on sites defined by Brown et al. (1993)

Site	DN	dS	dN/dS	P w ≠ 1	P w < 1
ABS N = 15	0.311 ± 0.118	0.407 ± 0.167	0.765	0.585	0.291
Non-ABS N = 42	0.084 ± 0.020	0.237 ± 0.064	0.353	0.065	0.030
All sites N = 57	0.131 ± 0.026	0.276 ± 0.060	0.474	0.039	0.020

ABS, antigen-binding sites; N, number of codons in each category; P, probability (α < 0.05) that dN and dS are different (w ≠ 1) and that dN<dS (w < 1) using a Z-test. Significant P-values are in bold.