A maximum-likelihood tree of 41 sequenced Legionella species was reconstructed based on concatenated amino-acid alignment of 78 orthologous ORFs. For each species the following are also illustrated: genome sizes (blue), number of ORFs (purple), number of effectors (red), and number of unique effectors (orange). The evolutionary dynamics in general, and specifically of effectors, differ between the two major clades (marked in dark red and dark green), and between these and the deep-branching clade (marked in brown). Bootstrap values are presented as part of Supplementary Figure 4.