Table 2.

Genes in the interval of elevated divergence between the Bristol and Hawaii haplotypes exhibit signatures of purifying selection. dN, nonsynonymous substitutions per nonsynonymous site. dS, synonymous substitutions per synonymous site. ω, the dN/dS ratio. These quantities were estimated by maximum likelihood with the PAML program (35).

GeneNo. of sites d N d S ω
To the left of the divergent interval
Y39G10AR.7 1422 0.001 0.000 -
mcm-4 2469 0.000 0.004 -
Y39G10AR.15 2112 0.001 0.000 -
Inside the divergent interval
srbc-64 870 0.018 0.147 0.124
Y39G10AR.16 * 681 0.019 0.106 0.181
ugt-31 1563 0.022 0.158 0.140
On the right boundary of the divergent interval
nekl-1 2949 0.001 0.019 0.050
  • * The Hawaii and Bristol sequences have different predicted splice sites on both sides of intron 3, resulting in several predicted amino acid residues that are not shared between the two alleles. We considered only the shared exonic sequences.

  • nekl-1 cDNAs from Bristol and Hawaii differ slightly from the predicted exon structure. We used the exon structure from our cDNA clones (8).