Fig. 2.

Evolution of “cheating” explains patchiness of siderophore production trait in the V. splendidus-like group. (A) Phylogenetic relationship, siderophore production, and siderophore synthesis and transport genes for sequenced strains in the V. splendidus-like group. The tree is based on 66 single-copy genes present in all of the sequenced isolates. The “sid-prod” column refers to the outcome of the phenotypic screen; “aer-syn” stands for aerobactin biosynthesis genes, “aer-txpt” for aerobactin-specific transport genes, “vf-syn” for vibrioferrin biosynthesis genes, and “vf-txpt” for vibrioferrin-specific transport genes. (B and C) Examples of configurations of siderophore synthesis and transporter gene clusters in producer and nonproducer strains. The figures show that nonproducer phenotype evolved from excision of the biosynthesis genes from the complete synthesis-transport cluster. Black and red stars in A indicate the presence of similar “cheater” gene cluster configurations as those shown in B and C (Figs. S1 and S2).