FIG 6.

Evolutionary history of 21 nodD nucleotide sequences inferred by using the maximum likelihood method and Tamura-Nei model (76). For strains with one copy, nodD1 is black; for strains with both, nodD1 and nodD2 are blue and green, respectively. The phenological and geographical distributions of the strains are indicated according to the key, based on information in Table 1. The tree with the highest log likelihood (−6,198.64) is shown. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1,000 replicates) is shown next to the branches (77). Initial tree(s) for the heuristic search were obtained automatically by applying neighbor joining and BioNJ algorithms to a matrix of pairwise distances estimated using the maximum composite likelihood (MCL) approach, and then selecting the topology with superior log likelihood value. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. This analysis involved 21 nucleotide sequences. There were a total of 986 positions in the final data set. Evolutionary analyses were conducted in MEGA X (78).