MIADLIKOWSKA, JOLANTA* AND FRANÇOIS LUTZONI. Department of Botany, The Field Museum, Chicago, IL 60605. - Coevolution of symbiotic associations within peltigerous lichens (Peltigerineae, Ascomycota).
The common occurrence of tri-membered symbiotic associations in the
Peltigerinae offers a unique opportunity for studying coevolutionary
trends among all symbionts involved in lichen symbioses. Based on a
phylogenetic study of SSU and LSU nrDNA from the mycobiont and the
cyanobiont found in a broad selection of species belonging to the
Peltigerineae, a monophyletic circumscription of the suborder is
proposed here. Ancestral symbiotic states (bi- versus tri-membered
symbioses) for peltigerous lichens were reconstructed using maximum
likelihood as the optimization criterion. In addition, the pattern of
transmission (horizontal versus vertical) of cyanobacterial lineages
during the evolutionary history of the Peltigerineae was
investigated.
Key words: coevolution, cyanobacteria., lichen symbiosis, molecular phylogenetics, SSU &LSU nrDNA, symbiotic ancestral character states