Biodiversity Patterns and Ecological Preferences of the Photobionts Associated With the Lichen-Forming Genus .

The worldwide, ecologically relevant lichen-forming genus currently includes 41 accepted species, of which the group (PSULgp) and the group (PSAXgp) have received considerable attention over recent decades; however, phycobiont diversity is poorly known in s. lat. Here, we studied the diversity of microalgae associated with 159 thalli collected from 30 locations, including nine spp.: , and . The mycobionts were studied by carrying out phylogenetic analyses of the nrITS. Microalgae genetic diversity was examined by using both nrITS and LSU rDNA markers. To evaluate putative species boundaries, three DNA species delimitation analyses were performed on and . All analyses clustered the mycobionts into two main groups: PSULgp and PSAXgp. Species delimitation identified 13 fungal and 15 algal species-level lineages. To identify patterns in specificity and selectivity, the diversity and abundance of the phycobionts were identified for each species. High specificity of each group for a given clade was observed; PSULgp associated only with clade I and PSAXgp with clade S. However, the degree of specificity is different within each group, since the PSAXgp mycobionts were less specific and associated with 12 spp., meanwhile those of PSULgp interacted only with three spp. Variation-partitioning analyses were conducted to detect the relative contributions of climate, geography, and symbiotic partner to phycobiont and mycobiont distribution patterns. Both analyses explained unexpectedly high portions of variability (99 and 98%) and revealed strong correlations between the fungal and algal diversity. Network analysis discriminated seven ecological clusters. Even though climatic conditions explained the largest proportion of the variation among these clusters, they seemed to show indifference relative to climatic parameters. However, the cluster formed by A/ B/ sp. 2/ sp. S02/ sp. 3A was identified to prefer cold-temperate as well as humid summer environments.