title: Integrating coalescent and phylogenetic approaches to delimit species in the lichen photobiont Trebouxia.
abstract: The accurate assessment of species boundaries in symbiotic systems is a prerequisite for the study of speciation, co-evolution and selectivity. Many studies have shown the high genetic diversity of green algae from the genus Trebouxia, the most common photobiont of lichen-forming fungi. However, the phylogenetic relationships, and the amount of cryptic diversity of these algae are still poorly understood, and an adequate species concept for trebouxiophycean algae is still missing. In this study we used a multifaceted approach based on coalescence (GMYC, STEM) and phylogenetic relationships to assess species boundaries in the trebouxioid photobionts of the lichen-forming fungus Lasallia pustulata. We further investigated whether putative species of Trebouxia found in L. pustulata are shared with other lichen-forming fungi. We found that L. pustulata is associated with at least five species of Trebouxia and most of them are shared with other lichen-forming fungi, showing different patterns of species-to-species and species-to-community interactions. We also show that one of the putative Trebouxia species is found exclusively in association with L. pustulata and is restricted to thalli from localities with Mediterranean microclimate. We suggest that the species delimitation method presented in this study is a promising tool to address species boundaries within the heterogeneous genus Trebouxia.
authors.affiliation: Department of Biological Sciences, Institute of Ecology, Evolution and Diversity, Goethe Universität, Max-von-Laue-Str. 13, D-60438 Frankfurt, Germany; Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, D-60325 Frankfurt, Germany. Electronic address: Anna.Sadowska-Des@senckenberg.de.
authors.forename: Anna D
authors.initials: AD
authors.lastname: Sadowska-Deś
authors.affiliation: Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, D-60325 Frankfurt, Germany.
authors.forename: Francesco
authors.initials: F
authors.lastname: Dal Grande
authors.affiliation: Science & Education, The Field Museum, 1400 S. Lake Shore Drive, Chicago, IL 60605, USA.
authors.forename: H Thorsten
authors.initials: HT
authors.lastname: Lumbsch
authors.affiliation: Department of Lichenology and Bryology, Botanische Staatssammlung München, Menzinger Straße 67, D-80638 München, Germany; GeoBio-Center, Ludwig-Maximilians Universität München, Richard-Wagner-Str. 10, D-80333 München, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Beck
authors.affiliation: Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, D-60325 Frankfurt, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Otte
authors.affiliation: Korean Lichen Research Institute, Sunchon National University, Suncheon 540-742, South Korea.
authors.forename: Jae-Seoun
authors.initials: JS
authors.lastname: Hur
authors.affiliation: Korean Lichen Research Institute, Sunchon National University, Suncheon 540-742, South Korea.
authors.forename: Jung A
authors.initials: JA
authors.lastname: Kim
authors.affiliation: Department of Biological Sciences, Institute of Ecology, Evolution and Diversity, Goethe Universität, Max-von-Laue-Str. 13, D-60438 Frankfurt, Germany; Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, D-60325 Frankfurt, Germany. Electronic address: Imke.Schmitt@senckenberg.de.
authors.forename: Imke
authors.initials: I
authors.lastname: Schmitt
mesh_terms: D000460:Chlorophyta / Q000145:classification* / Q000502:physiology*; D014644:Genetic Variation; D008011:Lichens / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D010802:Phylogeny; D012100:Reproduction, Asexual; D017422:Sequence Analysis, DNA
keywords: Cryptic species; Environmental specialization; Lasallia pustulata; Photobiont sharing; Terrestrial green algae