Format: ORAL

Robert Hadfield1,2, Teagan Mulford1,2, Nopparat Anantaprayoon3, Makani Fisher4, Steven D. Leavitt1,2,*

1 Department of Biology, Brigham Young University, Provo, UT 84602, USA 2 Monte L. Bean Museum, Brigham Young University, Provo, UT 84602, USA 3 Department of Botany, Kasetsart University, Bangkok, Thailand 4 Department of Entomology, Purdue University, West Lafayette, IN, 47907, USA

The northern North American Cordillera is a globally significant center of endemism. In western North America, imperiled arid steppe habitats support a number of unique species, including several endemic and threatened lichens. However, processes driving diversification and endemism in this region remains unclear, and genomic data can play critical roles in informing conservation decisions. Here, we investigate diversity and phylogeography of the threatened wanderlust lichens (mycobiont=Rhizoplaca species) which occur free on calcareous soils in steppe habitats in western North America. Wanderlust lichens comprise three species of lichen-forming fungi (LFF) Rhizoplaca arbuscula, R. haydenii, and R. idahoensis (endangered, IUCN Red List) which occur in fragmented populations in Idaho and Wyoming, with limited populations in southeastern Montana and northern Utah. Using a genome-skimming approach, we generated a 19.1Mb alignment, spanning ca. half of the complete LFF genome, from specimens collected throughout the entire range of wanderlust lichens. Phylogeographic analyses suggest that both dispersal and vicariance played a significant role throughout the evolutionary history of the vagrant Rhizoplaca clade, with most of the dispersal events originating from the Salmon Basin in eastern Idaho the center of diversity for this group. This has resulted in an unexpected number of morphologically distinct, and geographically restricted lineages. Furthermore, niche modelling suggests that vagabond lichens dont fully occupy the areas of highest distribution probability. In fact, documented records often occur in areas predicted to be only marginally suitable. These data suggest a potential mismatch between contemporary habitats outside of the center of diversity in eastern Idaho with the most suitable habitat, adding to the vulnerability of this imperiled complex of endemic lichens. We discuss how the implications of these findings can help guide conservation strategies for imperiled regional endemic lichens.