Fungal communities at the edge: Ecological lessons from high alpine fungi

One of the least studied ecosystems on Earth is the plant-free zone found between the alpine tundra zone and the zone of permanent ice and snow. This unique ecosystem-type occurs in all of the major mountain ranges on Earth and is especially widespread in the Andes and Himalayas. Here we describe recent molecular-phylogenetic studies of the fungi that inhabit these apparently barren soils. Sites that receive significant amounts of snowfall (in the Himalayas, Rocky and Andes ranges) are dominated by unique clades of zoosporic fungi (especially the Spizellomycetales), which likely use the saturated soil conditions during snow melt to complete their life cycles and then remain dormant for most of the year during periods of extreme cold and dryness. In more extreme sites that have very sporadic and shallow snow packs, such as the upper slopes of Llullaillaco Volcano (el. 6 741 m above sea level) on the Chilean-Argentinian border, fungal communities show very little diversity and are dominated by clades of yeasts related to the Antarctic endolithic yeasts in the Filobasidiales group. The other major group found on Llullaillaco form a clade most closely affiliated with the Dothideomycetes. Overall, our phylogenetic approach and spatially explicit sampling scheme allow us to formulate new hypotheses about the ecological functioning of fungi that inhabit critically endangered high elevation ecosystems.