Khomich Maryia, Kauserud Håvard, Logares Ramiro, Rasconi Serena, Andersen Tom
Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway.
Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway.
FEMS Microbiol Ecol. 2017 Apr 1;93(4). doi: 10.1093/femsec/fiw231.
Despite their obvious importance, our knowledge about the eukaryotic microbial diversity of inland waters is still limited and poorly documented. We applied 18S rDNA amplicon sequencing to provide a comprehensive analysis of eukaryotic diversity in 74 low-productivity lakes along a 750 km longitudinal transect (5.40-18.52°E) across southern Scandinavia. We detected a wide diversity of pelagic microbial eukaryotes, classified into 1882 operational taxonomic units (OTUs). The highest OTU richness was found in traditional phytoplankton groups like Dinoflagellata, Chrysophyceae, Chlorophyta and Cryptophyta. A total of 53.6% OTUs were primarily autotrophic, while 19.4% of the heterotrophic OTUs belonged to putative parasitic taxa. Except for a longitudinal trend in the relative influence of mixotrophs, there were no significant associations between major functional groups (autotrophs, heterotrophs and parasites) and spatial and environmental variables. Community dissimilarity increased significantly with increasing geographical distance between lakes. In accordance with earlier, microscopy-based surveys in this region, we demonstrate distinct gradients in protistan diversity and community composition, which are better explained by spatial structure than local environment. The strong association between longitude and protistan diversity is probably better explained by differences in regional species pools due to differences in landscape productivity than by dispersal limitation or climatic constraints.
尽管内陆水域的真核微生物多样性具有明显的重要性，但我们对其了解仍然有限，且相关记录不足。我们应用18S rDNA扩增子测序技术，对横跨斯堪的纳维亚半岛南部750公里纵向断面（东经5.40 - 18.52°）的74个低生产力湖泊中的真核生物多样性进行了全面分析。我们检测到了种类繁多的浮游微生物真核生物，它们被分类为1882个操作分类单元（OTU）。在传统浮游植物类群如甲藻门、金藻纲、绿藻门和隐藻门中发现了最高的OTU丰富度。共有53.6%的OTU主要为自养型，而异养型OTU中有19.4%属于假定的寄生类群。除了混合营养生物的相对影响存在纵向趋势外，主要功能类群（自养生物、异养生物和寄生虫）与空间和环境变量之间没有显著关联。湖泊之间的群落差异随着地理距离的增加而显著增加。与该地区早期基于显微镜的调查结果一致，我们证明了原生生物多样性和群落组成存在明显的梯度变化，空间结构比当地环境更能解释这些变化。经度与原生生物多样性之间的强关联，可能更好地由景观生产力差异导致的区域物种库差异来解释，而非扩散限制或气候约束。
