Evolution of cyanobacterial symbioses in Ascomycota.
Two fifths of the species in Ascomycota are lichen-forming, of which 10% and 3-4% have cyanobacteria as the primary and secondary photobionts respectively. To study the evolution of cyanobacterial symbioses, the phylogenetic relationships within the Ascomycota have been reconstructed. Phylogenetic analyses were made using direct optimization of nuclear SSU and LSU rDNA sequences under the parsimon