Molecular approach for assessing responses of microbial-feeding nematodes to burning and chronic nitrogen enrichment in a native grassland
Molecular approach for assessing responses of microbial-feeding nematodes to burning and chronic nitrogen enrichment in a native grassland
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DOI：
10.1111/j.1365-294x.2006.02971.x
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发表时间：
2006-08-01
影响因子：
4.9
通讯作者：
Herman, Michael A.
中科院分区：
文献类型：
--
作者：
Jones, Kenneth L.;Todd, Timothy C.;Herman, Michael A.
草原生态系统的初级生产力的很大一部分分配在地下，维持着丰富多样的微生物和土壤无脊椎动物群落。这些地下群落驱动着许多重要的生态系统功能，并对各种环境变化做出反应。线虫是草原土壤群落中丰富多样的组成部分，对改变的环境条件特别敏感，例如与火灾频率减少和氮富集相关的环境条件，其中以微生物为食的线虫表现出最一致的反应。然而，许多现有的表征线虫对环境变化反应的研究都是在科的分类水平上或按广泛的营养类别（例如食真菌动物、食细菌动物）进行的。属水平或以下水平对环境变化的差异反应发生的程度尚不清楚。因此，本研究的目的是利用分子方法在最低的分类分辨率水平上量化以微生物为食的线虫对氮富集和火灾频率变化的反应。使用 18S 核糖体 RNA 基因和 ITS1 区域的测序和定量聚合酶链反应 (PCR) 探针，我们鉴定了 4 个科的 19 种以微生物为食的线虫类群。当对不同处理的线虫进行取样时，我们发现一个科内的一些线虫类群对氮和燃烧处理的反应相似，而同一科内的其他类群的反应则截然不同。此外，尽管不同科的线虫对氮富集和燃烧的平均反应不同，但在跨越三个分类科的线虫类群中观察到类似的反应。因此，如果将线虫用作环境变化的指标，则应注意在尽可能低的分类水平上评估响应。
A substantial proportion of the primary productivity in grassland ecosystems is allocated belowground, sustaining an abundant and diverse community of microbes and soil invertebrates. These belowground communities drive many important ecosystem functions and are responsive to a variety of environmental changes. Nematodes, an abundant and diverse component of grassland soil communities, are particularly responsive to altered environmental conditions, such as those associated with reduced fire frequency and nitrogen enrichment, with the most consistent responses displayed by microbial-feeding nematodes. However, much of the available research characterizing nematode responses to environmental change has been carried out at the taxonomic level of family or by broad trophic categories (e.g. fungivores, bacterivores). The extent to which differential responses to environmental change occurs at the genus level or below is unclear. Therefore, the objective of this study was to use molecular methods to quantify the response of microbial-feeding nematodes, at the lowest levels of taxonomic resolution, to nitrogen enrichment and changes in fire frequency. Using sequencing and quantitative polymerase chain reaction (PCR) probes for the 18S ribosomal RNA gene and the ITS1 region, we identified 19 microbial-feeding nematode taxa across four families. When nematodes were sampled across treatments, we found that some nematode taxa within a family responded similarly to nitrogen and burning treatments, while other taxa within the same family respond quite differently. Additionally, although nematodes from different families on average responded differently to nitrogen enrichment and burning, similar responses were seen in nematode taxa that span three taxonomic families. Thus, if nematodes are to be used as indicators of environmental change, care should be taken to assess the response at the lowest taxonomic level possible.