Message - 7th IAL Symposium

Lichen: from genome to ecosystem in a changing world
1I-O
(1I-O6) Submission ID: IAL0069-00001
EVOLUTION OF PHOTOBIONT ASSOCIATIONS IN THE FAMILY VERRUCARIACEAE
Gueidan C. 1 , Thues H. 1 , Muggia L. 2 , Perez-Ortega S. 3 , Favero-Longo S. 4 , Joneson S. 5 , O’Brien H. 6 , Nelsen M. 7 ,
Duque-Thues R. 1 , Grube M. 2 , Friedl T. 8 , Brodie J. 1 , Andrew C.J. 7 , Lücking R. 7 , Lutzoni F. 9
1 Botany, Natural History Museum, London, United Kingdom
2 Institute of Plant Sciences, Karl-Franzens-University Graz, Graz, Austria
3 Departamento de Biología Ambiental, Museo Nacional de Ciencias Naturales, Madrid, Spain
4 Dipartimento di Biologia Vegetale, Università degli Studi di Torino, Torino, Italy
5 Department of Biological Sciences, University of Idaho, Moscow, United States
6 Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
7 Botany, The Field Museum, Chicago, United States
8 Abteilung für Experimentelle Phycologie und Sammlung von Algenkulturen, Georg August Universität Göttingen,
Göttingen,Germany
9 Biology, Duke University, Durham, United States
The lichen family Verrucariaceae is well known for its unique diversity in photobionts, including some
algae that are rarely or never associated with other lichens. The identity of these photobionts has been established
in the past based on morphological characters, but studies have highlighted the difficulty of accurate
species and genus identifications for most of these unicellular or short filamentous groups of algae with problematic
taxonomy. Recent studies on Verrucariaceae, mostly focusing on peculiar algal symbionts, have therefore
used molecular data to confirm the identity of these photobionts. Here, molecular data (rbcL and 18S) are used
to confirm the identity of a taxon sampling representative of most lineages within Verrucariaceae, including some
poorly known species from the tropics. Phylogenetic analyses show that a large number of species are associated
with the green algal genus Diplosphaera. Other algal genera consist in Auxenochlorella, Asterochloris,
Dilabifilum, Elliptochloris, Heterococcus, Myrmecia, Prasiola and Trebouxia. The most common lichen photobionts
(Trebouxia, Asterochloris, Trentepohlia and Nostoc) are never or seldom found associated with Verrucariaceae.
Amphibious species of Verrucariaceae show a particularly broad phylogenetic range of algal associates:
they were found with algal species from the Xanthophyceae (Heterococcus), Ulvophyceae (Dilabifilum), and
Trebouxiophyceae (Diplosphaera, Elliptochloris and Prasiola). The endolithic genus Bagliettoa also shows a high
diversity in photobionts (Asterochloris, Diplosphaera and Trebouxia). In contrast, the lichen lineage including
Placidium and Heteroplacidium, although colonizing different habitats (soil, bark, rock) is only associated with
algal species from the genus Myrmecia. When studied with comparative methods, the results suggest that both
habitat requirements and common ancestry were involved in shaping the current patterns of photobiont associations
in Verrucariaceae. Moreover, the presence of a developed upper cortex also plays an important role in the
evolution of photobiont associations in this family.
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