Centre for Biodiversity Genomics, University of Guelph, Guelph, ON, Canada.
Department of Integrative Biology, University of Guelph, Guelph, ON, Canada.
Mol Ecol. 2019 Dec;28(24):5347-5359. doi: 10.1111/mec.15292. Epub 2019 Nov 22.
Mites (Arachnida: Acariformes, Parasitiformes) are the most abundant and species-rich group of arthropods in soil, but are also diverse in freshwater habitats, on plants, and as symbionts of larger animals. However, assessment of their diversity has been impeded by their small size and often cryptic morphology. As a consequence, published estimates of their species richness span more than two orders of magnitude (0.4-114 million). In this study we employ DNA barcoding and the Barcode Index Number (BIN) system to investigate mite diversity at over 1,800 sites across Canada, primarily from soil and litter habitats with smaller contributions from freshwater, plants, and animal hosts. Barcodes from 73,394 specimens revealed 7,077 BINs with representatives from all four orders (Ixodida, Mesostigmata, Sarcoptiformes, Trombidiformes) and 60% (186) of the known families. The BIN total is 2.4 times the number of species previously recorded from Canada (2,999), reflecting the unexpectedly high richness of several families. Richness projections suggest that more than 28,000 BINs occur at the sampled locations, indicating that the Canadian mite fauna almost certainly includes more than 30,000 species-a total similar to that for the most diverse insect order in Canada, Diptera. This unexpected diversity was partitioned into highly dissimilar, spatially-structured assemblages that likely reflect dispersal limitation and environmental heterogeneity. Further sampling of a greater diversity of habitats will refine understanding of mite diversity in Canada, but similar analyses in other geographic regions will be essential to ascertain their diversity at a global scale.
螨类（蛛形纲：蜱螨目，真螨目）是土壤中最丰富和物种最多的节肢动物群，但在淡水生境、植物上以及作为较大动物的共生体中也具有多样性。然而，它们的体型小且形态通常具有隐蔽性，这阻碍了对其多样性的评估。因此，已发表的物种丰富度估计值跨越了两个数量级以上（0.4-11400 万）。在这项研究中，我们采用 DNA 条形码和条形码索引数（BIN）系统，对加拿大 1800 多个地点的螨类多样性进行了调查，主要来自土壤和凋落物栖息地，淡水、植物和动物宿主的贡献较小。来自 73394 个标本的条形码揭示了 7077 个 BIN，代表了所有四个目（硬蜱目、中气门目、真螨目、革螨目），其中 60%（186 种）是已知的科。总 BIN 数是以前从加拿大记录的物种数（2999 种）的 2.4 倍，反映了几个科出人意料的丰富度。丰富度预测表明，在采样地点存在超过 28000 个 BIN，这表明加拿大的螨类动物群几乎肯定包括 30000 多种物种——这一总数与加拿大最多样化的昆虫目（双翅目）相似。这种出乎意料的多样性被划分为高度不同的、空间结构的组合，这可能反映了扩散限制和环境异质性。对更多不同生境的进一步采样将完善对加拿大螨类多样性的理解，但在其他地理区域进行类似的分析对于确定全球范围内的多样性至关重要。
