FIG. 4.

Phylogenetic trees illustrating altered distribution of taxa when codons determining clade-specific differences are swapped between clades. Twenty sequences were selected at random from the clades indicated within dashed boxes. ML trees were constructed from nucleotides (midpoint rooted, bootstrap values based on 100 replicates). (A) Codons defining amino acids characteristic of clade A1 (selected from the clade A1 consensus) were superimposed on 20 sequences from clade B. The clade B sequences are shown twice, once without alteration (marked B) and once with A1-clade amino acids superimposed (marked B+A1). (B) Codons defining amino acids characteristic of clade C (selected from the clade C consensus) were superimposed on the same 20 sequences from clade B. As before, the clade B sequences are shown twice, unchanged (marked B) and bearing the characteristic C-clade codons (marked B+C).