Pair-wise gene possession comparisons among all 136 possible Staphylococcus aureus strains pairs. The comparison of two strains is summarized in the (4-level) box at the intersection of the row and column corresponding to the respective strains. Pair-wise relationships are summarized based on the number of genes with orthologs in each of the two strains (S = similarity score, level 1 of each box); the number of genes with an ortholog in one strain but not the other (D = difference score, level 2 of each box); a composite comparison score (C = S - D, level 3 of each box); and the number of genes with orthologs found only in both strains (P = pair unique score, level 4 of each box).
Boissy et al. BMC Genomics 2011 12:187 doi:10.1186/1471-2164-12-187