Data from: Integrating quantitative morphological and qualitative molecular methods to analyze soil nematode community responses to plant range expansion

1. Belowground nematodes are important for soil functioning, as they are ubiquitous and operate at various trophic levels in the soil food web. However, morphological nematode community analysis is time consuming and requires ample training. qPCR-based nematode identification techniques are well available, but high throughput sequencing (HTS) might be more suitable for non-targeted nematode community analysis. 2. We compared effectiveness of qPCR and HTS-based approaches with morphological nematode identification while examining how climate warming-induced plant range expansion may influence belowground nematode assemblages. We extracted nematodes from soil of Centaurea stoebe and C. jacea populations in Slovenia, where both plant species are native, and Germany, where C. stoebe is range expander and C. jacea is native. Half of each nematode sample was identified morphologically and the other half was analysed using targeted qPCR and a novel HTS approach. 3. HTS produced the highest taxonomic resolution of the nematode community. Nematode taxa abundances correlated between the methods. Therefore, especially relative HTS and relative morphological data revealed nearly identical ecological patterns. All methods showed lower numbers of plant feeding nematodes in rhizosphere soils of C. stoebe compared to C. jacea. However, a profound difference was observed between absolute and relative abundance data; both sampling origin and plant species affected relative abundances of bacterivorous nematodes, whereas there was no effect on absolute abundances. 4. Taken together, as HTS correlates with relative analyses of soil nematode communities, while providing highest taxonomic resolution and sample throughput, we propose a combination of HTS with microscopic counting to supplement important quantitative data on soil nematode communities. This provides the most cost-effective, in-depths methodology to study soil nematode community responses to changes in the environment. This methodology will also be applicable to nematode analyses in aquatic systems.

1. 地下线虫广泛分布于土壤食物网的各个营养级，对土壤生态系统功能至关重要。然而，线虫群落的形态学鉴定分析不仅耗时耗力，还需要充足的专业培训。基于实时定量聚合酶链式反应（quantitative PCR, qPCR）的线虫鉴定技术已较为成熟，但高通量测序（High Throughput Sequencing, HTS）或许更适用于非靶向性线虫群落分析。2. 本研究对比了qPCR、HTS与形态学鉴定三种线虫分析方法的有效性，同时探究了气候变暖驱动的植物分布范围扩张如何影响地下线虫群落组成。研究分别从斯洛文尼亚（两种植物均为本土物种）与德国（Centaurea stoebe为分布扩张物种，C. jacea为本土物种）的Centaurea stoebe和C. jacea种群土壤中提取线虫；每份线虫样本均分为两部分，一半进行形态学鉴定，另一半分别采用靶向qPCR与新型HTS方法开展分析。3. HTS在线虫群落的分类学分辨率上表现最优，三种方法得到的线虫类群丰度均具有相关性；其中，HTS相对丰度数据与形态学相对丰度数据所揭示的生态模式几乎完全一致。所有方法均显示，C. stoebe根际土壤中的植食性线虫数量显著低于C. jacea根际土壤。但绝对丰度与相对丰度数据间存在显著差异：采样来源与植物物种均会影响食细菌线虫的相对丰度，却不会对其绝对丰度产生作用。4. 综上，HTS不仅可与土壤线虫群落的相对丰度分析结果高度相关，还能提供最优的分类学分辨率与样本通量；因此本研究提出将HTS与显微计数法相结合，以补充土壤线虫群落的关键定量数据。该方案兼具高性价比与深入解析能力，是探究土壤线虫群落对环境变化响应的最优方法，同时也可应用于水生系统的线虫分析研究。