Phylogeny and species delimitation in Roccellaceae and Physciaceae (Euascomycetes)

Sammanfattning: DNA sequence data (the ITS region and Group I Introns) from the nuclear ribosomal repeat (rDNA), partial ?-tubulin gene sequences, RAPD markers, and some morphological characters were analysed phylogenetically in order to examine relationships in lichenized Euascomycetes, from the species level to higher taxonomic levels. The species level studies comprise some so-called species pairs in two families, Roccellaceae (Arthoniales) and Physciaceae (Lecanorales). In order to determine whether the asexual specimens studied represent clonal species that have arisen from their fertile counterparts in a single event, or alternatively have multiple origins and are therefore conspecific, the ITS region, and in some cases the ?-tubulin gene sequences and RAPD markers were obtained for several fertile and sterile specimens of various species pairs. A novel phylogenetic analysis of the species pair Phaeophyscia ciliata/P. orbicularis was introduced in this thesis. Molecular methods were also used to resolve the phylogeny of the family Physciaceae and the genus Physcia within it. The utility of indels (gaps) and different gap-coding in molecular data was also discussed.The DNA sequence data appeared to be informative. The ITS sequences provided abundant phylogenetic information at the family level, as well as at the genus and, in some cases, species levels. The intron positions varied between different genera and insertions were found to provide phylogenetic information mostly within and between species. The b-tubulin gene appeared to be an especially informative genetic marker at the species level.The results from the species pair studies indicated that the sexual and asexual specimens might be conspecific in many cases, since sexual and asexual counterparts were intermixed in the phylogenetic trees.