FIG. 1.

Phylogenetic tree of representative mcrA sequences and standards used for real-time quantitative PCR. Boxes denote sequences targeted by the respective TaqMan probe listed in Table 1. The tree was constructed as a maximum parsimony tree using close-neighbor interchange level 1 and bootstrapped with 1,000 trials. All positions containing gaps and missing data were eliminated from the data set. The scale bar represents the number of changes over the whole sequence. Classification of clusters is based on that reported by Castro et al. (8) for MCR-2, MCR-5, and MCR-7 and that of Juottonen et al. (24) for the Fen cluster.