Abstract Detail

Bryology and Lichenology

Simon, Antoine [1], Goffinet, Bernard [2], Magain, Nicolas [3], Serusiaux, Emmanuel [1].

Macroevolutionary patterns of an unsuspected species-rich lichen radiation: insights from the genus Sticta.

Rapid and potentially adaptive radiations characterize various lineages across the tree of life. Although lichenization may have been a key innovation in the diversification of fungi, rapid radiations and in particular insular radiations remain poorly known at best among lichen-forming fungi. Here we tested whether populations of Sticta in the Mascarenes and Madagascar arose from a unique shared ancestor and if they phylogenetically segregate in distinct insular endemics. We extensively sampled Sticta populations in montane forests on Mauritius, Reunion and Madagascar and produced the fungal ITS barcode sequence for 148 specimens of Sticta. We inferred the relationships among Sticta populations and species from a 4-loci data matrix assembled with 68 exemplars representing the diversity and geographical distribution of ITS haplotypes. Using a phylogenetic framework, bolstered by morphological assessment, we addressed the evolutionary relationships within this group, established species boundaries, and estimated the date of the most recent common ancestor. Our results provide evidence that a major clade of Sticta restricted to the Western Indian Ocean underwent a dramatic diversification following a single colonization event (c. 11 Mya). Phylogenetic inferences resolve indeed a diverse and robust clade comprising 31 endemic species of Sticta, albeit with highly homoplasious features, contrasting the five morphospecies previously recognized in this region. This study represents the first scenario where a local radiation of this magnitude is observed in lichens. The strong incongruence between the diversity of morphotypes and of molecular phylogenetic species, as well as the scattered distribution of specific morphotypes across the phylogeny suggest significant constraints or limits to the exploration of the morphological space to construct a stable lichen symbiosis within Sticta.

1 - University of Liège, Evolution and Conservation Biology, InBIOS research center, University of Liège, Quartier Vallée 1, Chemin de la Vallée 4, Liège, B-4000, Belgium
2 - University of Connecticut, Department Of Ecology & Evolutionary Biology, 75 North Eagleville Road, Storrs, CT, 06269, United States
3 - Duke University, Department of Biology, Box 90338, Durham, NC, 27708, United States

Keywords:
biogeography
Indian Ocean
Lobariaceae
Madagascar
Mascarenes
photomorphs
Radiation.

Presentation Type: Oral Paper
Session: 28, Bryology and Lichenology (ABLS) II
Location: Sundance 1/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 2:30 PM
Number: 28005
Abstract ID:431
Candidate for Awards:A. J. Sharp Award