Fig. 2

Pairwise single-nucleotide differences between isolates. SNP distances between every pair of isolates in the data set were calculated. Pairwise comparisons of isolates classified as different RFLP types have a peak at 148 differences. In comparisons among isolates with the same RFLP type, we observe a bimodal distribution of pairwise differences. This bimodal distribution reflects the structure within RFLP 0.0728, which is more genetically diverse than RFLP 0.0142. RFLP restriction fragment-length polymorphism, SNP single-nucleotide polymorphism