Phylogenetic tree of the 230 identified roo and rooA elements. The tree is based on the protein coding sequence of roo and rooA. It was constructed using PhyML with an approximate likelihood ratio test to estimate the statistical support of the tree topology , as shown by the numbers at the branches. All branches have a very high support. There is a clear division between roo (red background) and rooA (blue background) elements on the tree. Specifically, all roo elements from one species form a clade and the same holds for rooA. The black triangles at some leaves indicate the divergence of the elements associated with this leaf, with long triangles indicating great divergence. The number in brackets behind each species name indicates how many elements are present in the respective species.