Fig. 1
From: The impact of migratory flyways on the spread of avian influenza virus in North America
Viral migration and migratory flyways in North America. Viral migration rates were inferred from the PB2 gene segment (an exemplar of the AIV data set as a whole). US states and Canadian provinces (locations) are color-coded according to their flyway assignment. No viruses were analyed from locations that have a light color. The color of each line connecting two locations corresponds to the inferred rate. The absence of a line connecting two locations suggests that the migration rate was 0