Mountain ecosystems facing global warming: study of impact of snow cover parameters on microbial communities of nivicolous myxomycetes

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In Europe, vanishing glaciers – especially in the Alps – became a symbol for a period of rapid warming, also causing upward shifts of vegetation belts. Consequences are well studied for larger animals and vascular plants, but how will microbial communities adapt? We want to study potential responses in a group of protists, which are flagship species of undersnow microbial communities of the uppermost soil layer: the nivicolous myxomycetes. These predators of bacteria need a contiguous snow cover of several months to form macroscopic fructifications, which release airborne spores for long-distance dispersal. Through surveys of fruit bodies (via morphological assessment and genetic barcoding) and amoebal populations (via metabarcoding, both based on ribosomal DNA), we will assess genetic diversity, dispersal potential and resilience of nivicolous myxomycetes in relation to changes in snow cover. We will establish two transects spanning lowland regions (northern Germany / northern Poland, 0-300 m); low mountains (Harz / Sudetes, 600-1600 m); and high mountains (German Alps / Tatra Mts., 1000-2900 m). For each region we will establish 1-4 sites at different elevations to monitor fructifications and amoebal populations over three years. Both data sets will be used to estimate genetic diversity and dispersal abilities, explore the limits of population persistence under unstable climatic conditions, and model suitable belts for persistence of both amoebal and fruiting populations under climate-change scenarios.In contrast to studies of dispersal-limited alpine organisms, like vascular plants, this project will target a microbial group capable of long-distance dispersal. We hypothesize that (1) fructification propensity decreases with decreasing duration of snow cover and increasing risk of soil frost; (2) suitable belts for fruiting, i.e. actively dispersing, species move upwards with climate change but may face the limits of soil formation in high altitudes; (3) taller and larger mountain massifs are more diverse (at both the species and ribotype level) than smaller and lower ones, but many species may be able to endure as non-fruiting “sink” populations of amoebae at lower elevations. We will combine the taxonomic expertise of the Polish partner with barcoding and metabarcoding tools developed by the German partner to define the ecological requirements for this group of organisms more sharply and model possible reactions of myxomycete populations to unstable and/or disappearing snow cover.