Continent-wide analysis of moss diversity in Antarctica

Mosses play a key role in Antarctic ecosystems. Understanding of moss diversity and its likely drivers across Antarctica is, however, limited, as is the extent to which Antarctic Specially Protected Areas (ASPAs) represent this diversity. Both are important given changing climates and direct human impacts in the region. Here we investigate variation in moss diversity, the frequency distribution of their range sizes, and their continent-wide conservation. Richness is positively related to temperature, but negatively related to latitude, distance from bird colonies and geothermal sites; terrain roughness showed weak, yet positive, effects. Beta-diversity is similar to that found for assemblages separated by long distances, dominated by species turnover. Multi-site turnover (zeta diversity) suggests that niche-related mechanisms are likely more responsible for diversity patterns than neutral mechanisms, despite the significant role wind-driven dispersal is thought to play in structuring Antarctic biodiversity patterns. The frequency distribution of range sizes of mosses was right skewed, indicating that several moss species have very small range sizes, while a few species have larger ranges. Where ASPAs include mosses, richness varies between 1 and 41 species, with 65.1% (71 species) of the 109 species known from the continent included in the ASPA network. Twenty-four species lie within 25 km² radius of an ASPA, and 14 species beyond this distance could be considered relatively more difficult to protect. These findings lend support to the proposal that changing temperatures and expanding ice-free areas will substantially increase Antarctica's diversity. Nonetheless, the mosses are reasonably well represented by the ASPA network, contrasting with other Antarctic taxa.