Fig. 6

Phylogenetic tree of a transporter gene family (a) Simplified phylogenetic tree of the five lineages of B. graminis used in this study (modified form Menardo et al. [22]). The median estimation for the divergence time is reported at each bifurcation of the tree. b) Maximum likelihood tree of a major facilitator family (transmembrane transporters). This was randomly picked among non-effector genes families to show an example of the different patterns in the evolution of CEG families compared to non-CEG families. Branches are colored according to the lineage of B. graminis to which the respective effector gene belongs. The species tree with the color code is represented in panel a. Branch labels report the bootstrap support for the clade inferred with 1000 replications. The scale is in expected amino-acid substitutions per site. In this family, the average number of substitutions after divergence of the different lineages is much lower than in CEG families; this is represented by the short terminal branch lengths and could be explained by positive selection that fixes non-synonymous substitutions. Moreover, nine different genes are clearly recognizable. For five of them there is one copy for each lineage and for two of them the gene tree concords with the species tree. This is in contrast with effector gene families where it is often impossible to identify orthologous genes in the different lineages