Future Range Shifts and Diversity Patterns of Antarctic Lecideoid Lichens Under Climate Change Scenarios

Being uniquely adapted to extreme environmental conditions, rock-dwelling lecideoid lichens are a diverse and major component of terrestrial vegetation in Antarctica. Climate change is reshaping Antarctic ecosystems, potentially forcing cold-adapted species to shift their distributions to maintain their climatic niche. Here, we provide a circum-Antarctic assessment of lecideoid lichen diversity and project future distributional changes under contrasting climate change scenarios.

Fungal (mycobiont) and algal (photobiont) symbionts of lecideoid lichen species from a circum-Antarctic sampling were classified using DNA barcoding. The climatic niches of nine common mycobiont species and four photobiont OTUs were predicted, and spatial range shifts were projected across four Antarctic bioregions under three Shared Socioeconomic Pathways: (1) SSP1-2.6: sustainable development, (2) SSP3-7.0: medium–high reference scenario with high methane emissions and (3) SSP5-8.5: continued dependence on fossil fuels.

DNA-barcoding revealed 34 species of lecideoid lichens associated with nine photobiont OTUs for the Antarctic continent, including three previously undescribed species of the genus Lecidella.

Model projections indicate that future warming is likely to promote a range expansion rather than climate-induced habitat loss for both mycobionts and photobionts. Patterns of climate-induced range expansion differ markedly between maritime Antarctica and continental Antarctica. In the maritime Antarctic, Lecidea atrobrunnea and its main photobiont Tr_I01 are predicted to substantially increase their potential distribution, whereas the other species remain restricted to climatically distinct south-eastern regions of maritime Antarctica. In continental Antarctica, species show broadly similar expansion patterns, with the Transantarctic Mountains representing the region with the greatest projected gain in climatically suitable habitat.  Although the greatest range expansion generally occurs under SSP5-8.5, some photobiont OTUs in the Prince Charles Mountains are projected to gain more climatically suitable habitat under the high-methane scenario SSP3-7.0. Notably, areas of high climatic suitability are predicted to shift towards inland regions under future warming scenarios. Consequently, ice-free areas may function as potential refugia for cold-adapted lichen species under ongoing climate warming.

Overall, our results indicate that Antarctic lecideoid lichens are likely to undergo widespread range expansion under future warming, particularly into currently uncolonized ice-free inland areas of continental Antarctica. Projected shifts in climatically suitable areas suggest the emergence of new habitats, with potential consequences for future biodiversity patterns across Antarctica.