FIG. 2.

Phylogenetic tree of AiV strains identified in water samples from the Tamagawa River. The tree was constructed on the basis of sequences of a 224-nucleotide stretch within the 3CD junction region. The numbers on each branch indicate bootstrap values for the genotype, and bootstrap values of 950 or greater were considered statistically significant for grouping. The scale represents nucleotide substitutions per site. Circled numbers indicate AiV strains detected at each sampling site. The year and month are shown in bold italics beside the symbols.