Intra-specific genetic diversity and ecophysiological performance of the aeroterrestrial green alga Klebsormidium (Klebsormidiophyceae, Streptophyta) in biological soil crusts along a gradient of land-use intensity

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Aeroterrestrial filamentous green algae of the widely distributed, cosmopolitan genus Klebsormidium (Klebsormidiophyceae, Streptophyta) are typical components of biological soil crusts. These communities occur in all climatic zones and on all continents on Earth, where soil moisture is limiting. Biological crusts form water-stable aggregates that have important ecological roles in primary production, nitrogen fixation, nutrient cycling, water retention and stabilization of soils. Although available data on Klebsormidium are generally limited, its functional importance in biological soil crusts is regarded as high. Therefore, Klebsormidium will be investigated under different land-use intensities, as provided by the Biodiversity Exploratories, and in a changing world by a comprehensive evaluation of its intra-specific genetic diversity and ecophysiological performance. Such a combined approach has never been applied before to aeroterrestrial green algae, and hence represents one of the key innovations of this proposal. A representative set of soil samples will be collected from the experimental plots of the 3 research site in the Biodiversity Exploratories, from which unialgal Klebsormidium cultures will be established. Molecular-taxonomical characterisation of these strains will be undertaken using 18s rDNA, ITS-2 and rbcL markers. The intra-specific genetic diversity of strains of the same species will be evaluated using microsatellites. Based on the molecular data a range of selected genotypes of the same Klebsormidium species will be ecophysiologically characterised by comparatively measuring growth and photosynthesis as function of light, temperature, water and nutrient gradients to identify the physiological plasticity and ecological limits within the respective population. The data will indicate whether and how changes in land-use intensity will influence population structure and ecological performance of Klebsormidium in soil crusts.