IRTA-Institute for Food and Agricultural Research and Technology, Marine and Continental Waters Programme, Ctra de Poble Nou Km 5.5, E43540 Sant Carles de la Ràpita, Tarragona, Spain; Center for Climate Change (C3), Departament de Geografia, Universitat Rovira i Virgili, C/Joanot Martorell 15, E43500 Vila-seca, Tarragona, Spain.
IRTA-Institute for Food and Agricultural Research and Technology, Marine and Continental Waters Programme, Ctra de Poble Nou Km 5.5, E43540 Sant Carles de la Ràpita, Tarragona, Spain.
Sci Total Environ. 2021 Dec 1;798:149029. doi: 10.1016/j.scitotenv.2021.149029. Epub 2021 Jul 20.
Our study evaluates differences in the distribution and ecology of genetic variants within several ecologically important diatom species that are also key for Water Framework Directive monitoring of European rivers: Fistulifera saprophila (FSAP), Achnanthidium minutissimum (ADMI), Nitzschia inconspicua (NINC) and Nitzschia soratensis (NSTS). We used DADA2 to infer amplicon sequence variants (ASVs) of a short rbcL barcode in 531 environmental samples from biomonitoring campaigns in Catalonia and France. ASVs within each species showed different distribution patterns. Threshold Indicator Taxa ANalysis revealed three ecological groupings of ASVs in both ADMI and FSAP. Two of these in each species were separated by opposite responses to calcium and conductivity. Boosted regression trees additionally showed that both variables greatly influenced the occurrence of these groupings. A third grouping in FSAP was characterized by a negative response to total organic carbon and hence was better represented in waters with higher ecological status than the other FSAP ASVs, contrasting with what is generally assumed for the species. In the two Nitzschia species, our analyses confirmed earlier studies: NINC preferred higher levels of calcium and conductivity. Our findings suggest that the broad ecological tolerance of some diatom species results from overlapping preferences among genetic variants, which individually show much more restricted preferences and distributions. This work shows the importance of studying the ecological preferences of genetic variants within species complexes, now possible with DNA metabarcoding. The results will help reveal and understand biogeographical distributions and facilitate the development of more accurate biological indexes for biomonitoring programmes.
我们的研究评估了在几个具有重要生态学意义的硅藻物种中的遗传变异的分布和生态学差异，这些物种也是欧洲河流水框架指令监测的关键：Fistulifera saprophila (FSAP)、Achnanthidium minutissimum (ADMI)、Nitzschia inconspicua (NINC) 和 Nitzschia soratensis (NSTS)。我们使用 DADA2 推断了来自加泰罗尼亚和法国生物监测活动的 531 个环境样本中短 rbcL 条码的扩增子序列变异 (ASV)。每个物种内的 ASV 显示出不同的分布模式。指示性分类单元分析 (TIA) 揭示了 ADMI 和 FSAP 中 ASV 的三个生态分组。在每个物种中，有两个分组是通过对钙和电导率的相反反应来分离的。提升回归树还表明，这两个变量极大地影响了这些分组的出现。FSAP 的第三个分组的特征是对总有机碳的负响应，因此在生态状况较高的水域中比其他 FSAP ASV 更具代表性，这与人们通常对该物种的假设相反。在两个 Nitzschia 物种中，我们的分析证实了早期的研究：NINC 更喜欢更高水平的钙和电导率。我们的研究结果表明，一些硅藻物种的广泛生态耐受性是由于遗传变异之间重叠的偏好造成的，而这些遗传变异个体表现出更为有限的偏好和分布。这项工作表明，研究物种复合体中遗传变异的生态偏好具有重要意义，现在可以通过 DNA 宏条形码技术来实现。研究结果将有助于揭示和理解生物地理学分布，并为生物监测计划开发更准确的生物指标提供便利。
