Maximum clade credibility phylogeny and timing for the HA gene. Phylogeny was estimated within an MCMC framework using the GTR + G + Γ4 nucleotide substitution model, the Bayesian skyline coalescent demographic model and the uncorrelated lognormal relaxed molecular clock. H1N2 strains are colored according to the phylogenetic classification of the HA gene. The most interesting internal nodes, which reconstructed common ancestors with 95% credibility intervals, are reported. Numbers 2 and 3 refer to the reassortment events described in Figure 3. For each node posterior probability is reported.