Fungal biodiversity in the hypersaline Dead sea: Extinction and evolution

The Dead Sea is an extremely stressful hypersaline environment and a unique model for tracking evolutionary dynamics of biodiversity under increasing salinity. Dead Sea salinity stress eliminates most life forms except one alga, several species of Archaea, Bacteria, and filamentous fungi. Here we demonstrate, based on both seasonal (winter-summer) and inter-annual (2000-2015) evidence, that the turnover of fungal species diversity in the last 15 years decreased from 34 species in winter 2000 to 2 species in summer 2015. Species diversity steadily decreased and highly and significantly correlated with declining water level as well as increasing density and salinity stress, which is currently 348 gL^-1. The two surviving species, Aspergillus amstelodami Thom & Church and Aspergillus ruber Thom & Church, increased in frequency across all sampling sites, down to the Dead Sea bottom (-291 m), due to their evolved adaptations to tolerate hypersalinity. In summer 2015, most previously described fungi were not found except for the two aforementioned halophilic Aspergilli species. However, even the best adapted species to highly increased salinity decreased in frequency in the current extremely climaxing harsh conditions.