Green algae in soil: assessing their biodiversity and biogeography with molecular-phylogenetic methods based on cultures

• Main Author: Hodac, Ladislav
• Other Authors: Friedl, Thomas Prof. Dr., Daniel, Rolf Prof. Dr.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2016
• Subjects: 570; Green algae; soil; biodiversity; biogeography; 18S rDNA; ITS2 rDNA; monoclonal cultures; Biologie (PPN619462639); Antarctic; Arctic; Antarc*
• Online Access: http://hdl.handle.net/11858/00-1735-0000-0028-86B5-4; https://doi.org/10.53846/goediss-5497; https://nbn-resolving.org/urn:nbn:de:gbv:7-11858/00-1735-0000-0028-86B5-4-6

Green microalgae (Chlorophyta) dominate soils in the northern temperate climate zone, however, their biodiversity is still poorly understood. Available diversity inventories rely on light microscopy and morphospecies, which are hardly distinguishable without molecular markers. Whereas particular attention was paid to molecular diversity of terrestrial microalgae in extreme regions, temperate climate zones remain almost unexplored. We aim to uncover the phylogenetic diversity of green microlagae isolated from Central European soils and from periodically desiccating freshwater creek biofilms. Such terrestrial and semi-aquatic habitats are inhabited by green microalgae, which are presumably able of long-distance dispersal. Their cosmopolitan distribution is presumed, however, supporting molecular evidence is almost missing. By assembling newly obtained green algal sequences together with accessions from remote geographic regions, we further aim to address a question of biogeography of terrestrial microalgae. Soil samples were taken from grassland and forest plots within the German Biodiversity Exploratories. Freshwater biofilms dominated by green microalgae were sampled in two karstwater creeks in Germany. In total, 280 new monoclonal cultures of green microalgae were examined by molecular phylogenetic methods and by light microscopy. By using ribosomal 18S and ITS2 sequences, we recognized about 100 monophyletic species of green microalgae. The newly obtained sequences were blasted against public databases in order to infer taxonomy, distribution and ecology of the detected species. Further monoclonal cultures and environmental clones originated from additional samplings in Germany, Ecuador, the Arctic and Antarctic. Most Chlorophyta isolated from German soils were highly similar (≥ 99.5% threshold) to cultured relatives already known from Europe, predominantly from soils and further terrestrial substrates such as tree barks and rocks. Considering a lower similarity threshold (≥ 99%), about 90% of our cultures ...