Macroecological diversification and convergence in a clade of keystone symbionts

ABSTRACT Lichens are classic models of symbiosis, and one the most frequent nutritional modes among fungi. The ecologically geographically widespread lichen-forming algal (LFA) genus Trebouxia is best-studied groups LFA associates with over 7000 fungal species. Despite its importance, little known about diversification. We synthesized twenty years publicly available data by characterizing ecological preferences this group testing for time-variant shifts in climatic regimes a distribution trees. found evidence limited regimes, but that disparate lineages convergently evolved similar tolerances. Early were largely forest specialists or habitat generalists occupied regime whose extant members occur moderate climates. then diversified non-forested habitats expanded into modern representatives occupy wet-warm cool-dry rejected which diversification slowed through time, suggesting inconsistent expected under an adaptive radiation. In addition, we vegetative broadly coincided evolution biomes associated taxa. Together, our work illustrates how keystone symbiont from iconic symbiosis to diverse across globe.