Predicting Climatic Niche Shifts and Future Range Dynamics of Antarctic Rock-Dwelling Lichens Under Climate Change Scenarios

Saxicolous lecideoid lichens form a major part of the existing terrestrial vegetation in Antarctica. Lichens are formed by an association between a fungal (mycobiont) and a photosynthesizing (photobiont) symbiont. Adapted to extreme habitats, their distribution is primarily determined by macroclimatic conditions, with climate change presenting a significant challenge to these specialized organisms. In our study we assessed the current climatic niches of 9 circumantarctic mycobiont species and their associated photobiont OTUs and predicted the niche shifts of this species under two contrasting climate forcing scenarios (RCP2.6 and RCP8.5).

Our findings do not indicate a distinct climatic differentiation between the current niches of the symbiont pairs. However, the changes in potential niche areas suggest a general trend of niche expansion for all species under both climate scenarios (RCP2.6 andRCP8.5). For each species, the projected area gain is predicted to exceed the corresponding area losses due to climate warming. The niche expansion is primarily driven by the shift of niches inland, as new areas become suitable. While newly exposed rock surface due to snowmelt may contribute to the niche expansion for specific species on the Antarctic Peninsula, the overall impact on the continental Antarctic is insignificant. Our analysis indicates a general increase of niche overlap between species across all regions, except in the maritime Antarctic, where the complete loss of species niches was predicted. A broader pattern emerges in which regions with higher probable species richness are expected to shift inland, while coastal areas are likely to experience a decline in species numbers.