Split decomposition graphs for the rat PSG N1 domain exons, human PSG N domain exons, and baboon PSG N domain exons for observed (Hamming) distances. Split decomposition analysis was performed using nucleotide sequences for individual groups of PSG domain exons. (A) rat N1 domain exons; (B) human N domain exons; (C) baboon N domain exons. Scale bars represent 0.01 nucleotide substitutions per site. In (A) the putative N1 domain exon splice variants of PSG40 are identified with the suffix 'v1' for the published variant (NM_021677) and 'v2' for our predicted variant.