Fig. 7

Possible gain–loss-scenarios for plant mitochondrial group II introns. A Cladograms for alternative phylogenies “NLE/HT” (Non-Liverwort Embryophyte and Hornwort-Tracheophyte clades, left) and alternative “BRY/SET” (monophyletic Bryophyte and Setaphyte clades, right). Further labels indicate Streptophytes (STR), Embryophytes (EMB), Liverworts (LIV), Mosses (MOS), Hornworts (HOR), Lycophytes (LYC), Tracheophytes (TRA), Euphyllophytes (EUP), Ferns (FER), Gymnosperms (GYM), Angiosperms (ANG), Spermatophytes (SPE), and Streptophyte algae (ALG). Bars indicate plant mitochondrial group II intron gains (blue) and losses (red) after search for maximum parsimony evolution for the distribution of 101 embryophyte mitochondrial group II introns assuming weights of 4 to 1 for gains over losses. Underlining of rrnLi833g2 and cox2i104g2 highlights likely independent gain events as discussed in the text. Numbers before and after the pipes indicate intron gain and loss events. Hatched blue areas indicate introns grouped into families and the origin of the respective families are indicated on the respective branches. B Detailed listing for gains and losses of the embryophyte group II introns with those common to both evolutionary scenarios on top and those that need to be specifically assumed for the NLE/HT scenario (asterisks, total 102 gain and 190 loss events) shown below to the left and those for the BRY/SET scenario (double asterisks, total 103 gain and 199 loss events) shown below to the right