Figure 4

The maximum-likelihood phylogenetic tree of LpxM and LpxL proteins. Circles at internal nodes indicate bootstrap-supporting values as follows: black circles ≥ 95%, gray circles ≥ 85%, and white circles ≥ 70%. Proteobacteria are shown with green letters and lines. Group-II Gammaproteobacteria are indicated by *. See Figure 2 legend for abbreviations used for bacterial classification. Red arrowheads indicate where the duplication events happened. Light-red arrowheads are where the species-specific duplications are found.