Fig. 1.

The abridged majority-rule consensus tree summarizing the results from the MrBayes analysis of complete env genes. The branch lengths represent the mean value observed for that branch among the postburnin sampled trees. Posterior probabilities are indicated for each node. As expected under a “Haiti-first” model, the non-Haitian subtype B strains are phylogenetically nested within an older and more diverse range of Haitian viral variants. The 11 sequences of the Trinidad and Tobago clade and the 96 sequences of the pandemic clade are schematically represented by the blue and yellow triangles, respectively. Haitian or Haitian-linked sequences are shown in green, with the archival sequences labeled in larger bold text. The unabridged tree is available as SI Fig. 4.