Distribution of stop codons in the pseudogenes according to the amino acid position in the sequences. The positions of the stop codons are not distributed evenly across the various diploid species. The A genome sequences have a high percentage of stop codons at positions 24, 42, 145, 199 and these four stop codons may occur jointly in one pseudogene sequence. The B genome sequences also contain a high percentage of the jointly occurring stop codons at position 24, 145 and 199 but do not contain the stop codon at position 42. The jointly occurring stop codons 24, 145 and 199 are present in a few pseudogenes originating from the D genome. Pseudogenes from the A genome may contain another pair of jointly occurring stop codons at position 113 and 184 whereas the pair at positions 64 and 121 occurs in B genome pseudogenes, and pairs of stop codons at positions 65 and 83 and at the positions 99 and 252 occur in D genome pseudogenes.