Fig. 6.

Spatial locations of amino acid substitutions in oyster bindin repeats threaded onto the F-lectin crystal structure. Numbers refer to the amino acid position within the repeat. Eight of the nine positively selected sites (estimated dN/dS >1; gray spacefill) are clustered on the sugar binding face of the lectin and surround the 1H and 2R residues of the fucose-recognition motif (black spacefill; Fig. 2). The average distance between these eight positively selected sites is less than that expected by chance (n = 8, P < 0.009, 10⁶ replicates). Polymorphic sites (white spacefill) have amino acid substitutions observed in two or more cDNA sequences. Singleton sites (not depicted) are substitutions observed in only one cDNA sequence. Polymorphic (n = 21, P < 0.783, 10⁶ replicates) and singleton sites (n = 24, P < 0.082, 10⁶ replicates) are not spatially clustered.