2010). Because of their slow growth, lichens cannot compete effectively against vascular plants but, in areas with extreme abiotic conditions such as long periods of drought or cold, higher plants are excluded and lichens fill this important niche (Lalley et al. 2006). The symbiotic life form of lichens is composed of a fungal (mycobiont) and an photosynthetic partner (photobionts), and the latter can be an eukaryotic green alga (chlorobiont) and/or a cyanobacterium (cyanobiont). The ability of mycobionts to switch photobionts (Nelsen and Gargas

2009; Otalora et al. 2010; Henskens et al. 2012) and associate with more than one photobiont species or genotype along a climatic gradient appears to be a mechanism used by lichens to adapt to particular habitats. This has been reported for crustose lichens (Blaha et selleck al. 2006; Muggia et al. 2008; Ruprecht et al. 2012) and for fruticose lichens (Kroken and Taylor 2000). The influence of photobiont selection on the ecological amplitude of lichens is still largely underexplored Panobinostat mouse (Peksa and Skaloud 2011) and shedding more light on this phenomenon would help towards understanding structure,

composition and development of BCSs (Bowker 2007; Lazaro et al. 2008). The research reported here is part of the international and interdisciplinary SCIN-Project (Soil Crust InterNational; please see Büdel et al. 2014) which focuses on the biodiversity, the ecological roles and BCKDHA functions of BSCs in four different sites which differ substantially from each other in terms of soil composition, sea-level, seasonal temperatures and precipitation. An important first step is to identify the photobionts that occur in any particular lichen species. The major goal, therefore, of the present study was determining the biodiversity of green algal photobionts (chlorobionts) of the soil crust lichen Psora decipiens by molecular methods. The crustose green-algal lichen P. decipiens (Hedw.) Hoffm. [Lecidea d. (Hedw.) Ach.], to date described

as being only associated with Asterochloris sp. (Schaper and Ott 2003), is an important component of BSC at all four SCIN locations and provides an opportunity to investigate photobiont heterogeneity within a widespread lichen species. Molecular analysis of the soil crust lichens’ fungal partner is part of another study within the SCIN project. Additionally, we aimed to refine molecular methods to better handle the difficulties that arise in the molecular analysis of soil crust samples because of the presence of multiple organisms. Materials and methods Investigation sites and material Sixty-four samples of the key lichen on soil crusts, P. decipiens together with other species (see Online Resource 1) were collected at the four investigation sites of the SCIN-Project which cover both latitudinal and altitudinal gradients. For more detailed site descriptions and maps please see Büdel et al. (2014). 1. Tabernas field site, SE Spain (37.0127222°, −002.4356389°).