Abstract of paper 2:

Werth, S., F. Gugerli, R. Holderegger, H. H. Wagner, and C. Scheidegger. In prep. Landscape genetics of the lichen epiphyte Lobaria pulmonaria.

Epiphytes are strongly affected by the population dynamics of their carrier trees, and thus, substantial dispersal rates and corresponding high levels of gene flow are needed for populations to persist in a landscape. On the other hand, several epiphytic lichens have been suggested to be dispersal limited, implying that populations of lichens may be isolated and gene flow low. Here, we analyze landscape-level population genetic data from a potentially dispersal-limited epiphytic lichen. High amounts of historical gene flow were detected at the landscape level in 895 thalli of Lobaria pulmonaria genotyped at six fungal microsatellites. Bayesian analysis revealed spatially intermingled gene pools in the studied landscape. We also assessed effectiveness of landscape structures as potential barriers to gene flow and show that a large almost unforested area did not restrict historical gene flow. Our result of substantial gene flow at the landscape level emphasizes that (1) populations of epiphytic lichens may occupy large areas and that (2) dispersal limitation in epiphytic lichens may not be as relevant as previously assumed. Such large continuous populations are structured, at the most, by weak internal isolation by distance.