Table 1.

Divergence in exons and introns of rodent and primate OPRM1 genes*

	CDSs/UTRs		Upstream intron		Downstream intron
	Ka	Ks or Ku	3′_50	Central	5′_50	Central
Mouse–rat
Exon 11	—	0.116	—	—	0.131	0.199
Exon 1	0.031	0.118	0.110	0.173	0.114	0.136
Exon 13	—	0.146	0.109	0.177	0.063	0.171
Exon 2	0.004	0.317	0.134	0.171	0.041	0.129
Exon 3	0.005	0.316	0.131	0.129	0.185	0.173
Exon 18	0.079a	0.176/0.113a	0.161	0.187	0.087	0.165
Human–Macaca
Exon 11	—	0.040	—	—	—	0.068
Exon 1	0.014	0.014	0.020	0.068	0.064	0.062
Exon 13	—	0.071	0.109	0.064	0.064	0.074
Exon 2	0.004	0.051	0.085	0.074	0.041	0.057
Exon 3	0.005	0.069	0.042	0.057		0.054
Exon 18	—	0.063	0.041	0.069	0.020	0.065
Mouse–human
Exon 11	—	0.378	—	—	0.458	0.632
Exon 1	0.100	0.465	0.218	0.632	0.579	0.773
Exon 13	—	0.433	0.352	0.502	0.667	0.608
Exon 2	0.007	0.563	0.517	0.608	0.420	0.481
Exon 3	0.011	0.903	0.240	0.481	0.574	0.530
Exon 18	—	0.847	0.134	0.535	0.383	0.579

Evolutionary rates at non-synonymous (K_a) and synonymous (K_s) sites were calculated for coding exons by PAML (69). Evolutionary rates at non-coding exons (K_u) and for intronic sequences (K_i) were calculated using Kimura’s two-parameter model (70). The K_i values for central parts and for the end 50 nucleotide regions (3′_50 and 5′_50) of introns were calculated separately, because ∼50 nucleotide sequences at each end of an intron are thought to be subject to weak purifying selection that stems from the involvement of these sequences in splicing (39,78).

^aFor partially coding exons, K_a and K_s were calculated for cording parts and K_u was calculated for non-coding sequences.