Polar Terrestrial Environmental Systems, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany.
Department of Geography and Biology, North-Eastern Federal University of Yakutsk, Yakutsk, Russia.
PLoS One. 2020 Apr 15;15(4):e0230284. doi: 10.1371/journal.pone.0230284. eCollection 2020.
Large, old and heterogenous lake systems are valuable sources of biodiversity. The analysis of current spatial variability within such lakes increases our understanding of the origin and establishment of biodiversity. The environmental sensitivity and the high taxonomic richness of diatoms make them ideal organisms to investigate intra-lake variability. We investigated modern intra-lake diatom diversity in the large and old sub-arctic Lake Bolshoe Toko in Siberia. Our study uses diatom-specific metabarcoding, applying a short rbcL marker combined with next-generation sequencing and morphological identification to analyse the diatom diversity in modern sediment samples of 17 intra-lake sites. We analysed abundance-based compositional taxonomic diversity and generic phylogenetic diversity to investigate the relationship of diatom diversity changes with water depth. The two approaches show differences in taxonomic identification and alpha diversity, revealing a generally higher diversity with the genetic approach. With respect to beta diversity and ordination analyses, both approaches result in similar patterns. Water depth or related lake environmental conditions are significant factors influencing intra-lake diatom patterns, showing many significant negative correlations between alpha and beta diversity and water depth. Further, one near-shore and two lagoon lake sites characterized by low (0-10m) and medium (10-30m) water depth are unusual with unique taxonomic compositions. At deeper (>30m) water sites we identified strongest phylogenetic clustering in Aulacoseira, but generally much less in Staurosira, which supports that water depth is a strong environmental filter on the Aulacoseira communities. Our study demonstrates the utility of combining analyses of genetic and morphological as well as phylogenetic diversity to decipher compositional and generic phylogenetic patterns, which are relevant in understanding intra-lake heterogeneity as a source of biodiversity in the sub-arctic glacial Lake Bolshoe Toko.
大型、古老且异质的湖泊系统是生物多样性的宝贵资源。分析这些湖泊当前的空间变异性可以增进我们对生物多样性起源和建立的理解。硅藻对环境敏感且分类丰富，是研究湖泊内变异性的理想生物。我们调查了西伯利亚大型古老亚北极湖博尔绍托科的现代湖泊内硅藻多样性。本研究使用了硅藻特异性代谢组学，应用短 rbcL 标记结合下一代测序和形态鉴定，分析了 17 个湖泊内地点的现代沉积物样本中的硅藻多样性。我们分析了基于丰度的分类分类多样性和属系统发育多样性，以调查硅藻多样性变化与水深的关系。这两种方法在分类鉴定和 alpha 多样性方面存在差异，表明遗传方法通常具有更高的多样性。就 beta 多样性和排序分析而言，这两种方法产生的结果相似。水深或相关湖泊环境条件是影响湖泊内硅藻模式的重要因素，alpha 和 beta 多样性与水深之间存在许多显著的负相关关系。此外，一个近岸和两个泻湖湖点水深较低（0-10m）和中等（10-30m），具有独特的分类组成，这很不寻常。在水深较大（>30m）的地点，我们发现 Aulacoseira 的系统发育聚类最强，但 Staurosira 的聚类通常较弱，这支持水深是 Aulacoseira 群落的一个强有力的环境筛选因素。我们的研究表明，结合遗传和形态以及系统发育多样性的分析来破译组成和属系统发育模式是有用的，这对于理解亚北极冰川湖博尔绍托科的湖泊内异质性作为生物多样性的来源具有重要意义。
