Thallus Growth Stage and Geographic Origin Shape Microalgal Diversity in <i>Ramalina farinacea</i> Lichen Holobionts

Lichen symbioses are microecosystems hosting many other living organisms besides the two major lichen symbionts (i.e., lichenized fungi [the mycobiont] and green microalgae or cyanobacteria photobiont]). Recent investigations evidenced that fungi, non-photosynthetic bacteria, co-inhabit within thalli, but their diversity roles still underinvestigated. Here we present an ad hoc stratified sampling design in-depth Illumina paired-end metabarcoding approach to explore microalgal in thalli of model species Ramalina farinacea from different ecologies. were surveyed according three sizes, thallus parts considered for molecular, bioinformatics, community analyses. The results revealed strongly depends on growth stage geographic area, habitat type. also show does not vary along branches (lacinias)—that is, it correlate with apical founder effects—and there is no balanced co-presence main photobionts as previously established R. farinacea. performed here minimizes bias assessment photobiont lichens proposed be reliable applicable further study symbioses.