Phylogenetic relationships of the VXRs. The unrooted dendrogram was compiled following extraction of the repeat sequences from the SIs ofV. cholerae (VCRs in black ), V. metschnikovii (VMeRs in blue), and V. fischeri (VFRs in red) using the XXR program. The VXRs of the other species are omitted for clarity. The significance of the red- and green-framed VXRs are discussed in the text. Filled boxes denote VXRs that are descended from a common ancestor.