Figure 6.

Phylogenic relationship of sequences from the PA segment of avian influenza viruses isolated from northern pintails in Alaska (AK; Koehler et al. 2008) and California (CA; this study) in comparison to 36 reference samples from Asia (shaded ovals) and five from North America (NA). Circled numbers indicate the frequency of outsider events in each clade, including the five reassortment events identified by Koehler et al. (2008) for this RNA segment. The tree is rooted using two equine influenza isolates from North America. Bayesian posterior probabilities and levels of neighbor-joining bootstrap support >70% between major clades are shown on branches.