Figure 1.

Phylogenetic tree based on the aligned H8, H9, H12, and H19 HA gene nucleotide sequences. Avian H9 subtype viruses are coded with green, bat H9 with red, and H19 with blue. Outgroup is black. A time-measured phylogeny using the BEAST v. 2.7.5 package based on the tip dates of each strain. The substitution model GTR with estimated base frequencies, four gamma categories, and invariant sites (GTR + F + I + G4) was applied. A fast relaxed clock with lognormal distribution was chosen, and the tree prior was set to Coalescent Skyline. The scale bar indicates the years before the most recent sampling time (2021).