Background
Lichens are micro-ecosystems relying on diverse microorganisms for nutrient cycling, environmental adaptation, and structural support. We investigated the spatial-scale dependency of factors shaping the ecological processes that govern lichen-associated bacteria. We hypothesize that lichens function as island-like habitats hosting divergent microbiomes and promoting landscape gamma-diversity. Three microenvironments —thalli, substrates, and neighboring soils— were sampled from four geographically overlapping species of
Peltigera
cyanolichens, spanning three bioclimatic zones in the Chilean Patagonia, to determine how bacterial diversity, assembly processes, ecological drivers, interaction patterns, and niche breadth vary among
Peltigera
microenvironments on a broad geographical scale.
Results
The hosts’ phylogeny, especially that of the cyanobiont, alongside climate as a secondary factor, impose a strong ecological filtering of bacterial communities within
Peltigera
thalli. This results in deterministically assembled, low diverse, and phylogenetically convergent yet structurally divergent bacterial communities. Host evolutionary and geographic distances accentuate the divergence in bacterial community composition of
Peltigera
thalli. Compared to soil and substrate,
Peltigera
thalli harbor specialized and locally adapted bacterial taxa, conforming sparse and weak ecological networks.
Conclusions
The findings suggest that
Petigera
thalli create fragmented habitats that foster landscape bacterial gamma-diversity. This underscores the importance of preserving lichens for maintaining a potential reservoir of specialized bacteria.
Supplementary Information
The online version contains supplementary material available at 10.1186/s40793-024-00598-x.