Figure 5.

Distance matrix for the similarity in codon usage between pairs of viruses and pairs of hosts. Color code is based on the ranking of all 900 L₂ values, as calculated from all pairs of 30 viruses and 30 unique hosts. The matrix is organized by groups according to Table I. (A) Symmetric L₂ distance matrix for all 30 viruses (B) Symmetric L₂ distance matrix for all 30 hosts. The analysis is based on the complete proteomes of the mapped viruses. The sub-matrices indicate the partition into groups of mammals (1–11), aves (12), insects (13–16), plants (17–20), and bacteria (21–30). Note the large diversity among viruses infecting mammals, insects, and bacteria (A) and the strong resemblance among the mammalian hosts (B). Source data is available for this figure at www.nature.com/msb.