Leeches play important roles in food webs due to their abundance, diversity and feeding habits. Studies using invertebrate-derived DNA (iDNA) extracted from leech gut contents to target vertebrate DNA have focused on the Indo-Pacific region and mainly leveraged the leech family Haemadipsidae, composed of bloodfeeding terrestrial leeches, while predatory, fluid/tissue-feeding and aquatic bloodfeeding species have been largely disregarded. While there is some general knowledge regarding the taxonomic groups that leeches prefer to feed on, detailed taxonomic resolution is missing and, therefore, their potential use for monitoring animals is unknown. In this study, 116 leeches from 12 species (six families) and spanning the three feeding habits were collected in Mexico and Canada. We used DNA metabarcoding to investigate their diet and assess their potential use for biodiversity monitoring. We detected vertebrates from five orders including fish, turtles and birds in the diet of aquatic bloodfeeding leeches; eight invertebrate orders of annelids, arthropods and molluscs in leeches that feed on body fluids and tissues; and 10 orders of invertebrates belonging to Arthropoda and Annelida, as well as one vertebrate and one parasitic nematode, in predatory leeches. These results show the potential use of iDNA from aquatic bloodfeeding leeches for retrieving vertebrate taxa, and from predatory and fluid-feeding leeches for invertebrates. Our study provides information about the dietary range of freshwater leeches and one terrestrial leech and contributes proof-of-concept for the use of these leeches for animal monitoring, expanding our knowledge of the use of iDNA from leech gut contents to North America.

中文翻译：

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水生吸血和非吸血水蛭作为 iDNA 表征工具的潜力


由于其丰富性、多样性和食性，水蛭在食物网中发挥着重要作用。使用从水蛭肠道内容物中提取的无脊椎动物来源 DNA (iDNA) 来定位脊椎动物 DNA 的研究主要集中在印度-太平洋地区，主要利用水蛭科 Haemadipsidae，该家族由吸血的陆生水蛭组成，同时由捕食性、液体/组织喂养和水生水蛭组成。吸血物种在很大程度上被忽视了。虽然对水蛭喜欢吃的分类群有一些常识，但缺乏详细的分类解析，因此，它们在监测动物方面的潜在用途尚不清楚。在这项研究中，在墨西哥和加拿大收集了来自 12 个物种（6 个科）、跨越三种食性的 116 只水蛭。我们使用 DNA 元条形码来研究它们的饮食并评估它们在生物多样性监测中的潜在用途。我们在水生吸血水蛭的食物中检测到了鱼类、龟类和鸟类等 5 个目的脊椎动物；水蛭中以体液和组织为食的环节动物、节肢动物和软体动物的八个无脊椎动物目；捕食性水蛭中属于节肢动物门和环节动物门的 10 种无脊椎动物，以及一种脊椎动物和一种寄生线虫。这些结果表明，来自水生吸血水蛭的 iDNA 可用于检索脊椎动物类群，以及来自捕食性和食液水蛭的 iDNA 用于检索无脊椎动物。我们的研究提供了有关淡水水蛭和一种陆生水蛭的饮食范围的信息，并为使用这些水蛭进行动物监测提供了概念验证，从而将我们对水蛭肠道内容物 iDNA 使用的知识扩展到北美。