Figure 3

Phylogeny of group I introns. Phylogeny of fungal group I introns implicated in reverse splicing movement. This is a JC-NJ tree that was inferred for 116 fungal introns. The results of a JC-NJ bootstrap analysis are shown above the branches, whereas the results of an unweighted maximum parsimony bootstrap analysis are shown below the branches. The thick branches represent ≥95% Bayesian posterior probability. Branch lengths are proportional to the number of substitutions per site (see legend). The Symbiotaphrina spp. group I introns are marked with the filled triangles and the P. perisidiosa introns are marked with the filled circles. The intron insertion sites in small (S) and large (L) subunit rDNA are shown. The filled squares at the nodes denote the putative cases of intron movement. The colors for the different introns reflect the taxonomic position of the host cell containing the ribozymes (consistent with the scheme shown in Fig 2).