Fig. 6

Maximum likelihood phylogeny of the BioDA protein in the Ascomycota: Emergence of the [D2,3] stwintron. Taphrinomycotina proteins constitute the outgroup. Branch statistics are given as Approximate Likelihood Ratio Test values (0–1) at each node. The branches are color coded to distinguish classes of Pezizomycotina, as described in the legend to Fig. 3. Some fungal taxa are collapsed, to the level of whole classes for most of the Pezizomycotina. Taxa in which the stwintron occurs—Sordariomycetes and Botryosphaeriales—are underlined. The two groups of Sordariomycetes that stand out for the absence of intronic sequences at the bioDA stwintron position—members of two families of Diaporthales and five species of the order of the Ophiostomatales, respectively—are cartooned (blue) rather than collapsed. The branch where the stwintron has emerged at the position of an ancient intron is indicated by the upper yellow arrow. The latter “host” intron occurs in many species of non-Dikarya (see “Results” section): To indicate its kingdom-wide existence, the lower yellow arrow points at the origin of the tree. Note that a Maximum Likelihood phylogeny based on an alignment calculated using more stringent parameters (similarity matrix BLOSUM62) suggested that the Botryosphaeriales clade is paraphyletic to the (main) Sordariomycetes clade