Tracing the spread of European earthworms into North America using molecular markers and field experiments

北美大部分地区没有本地蚯蚓物种，大概是由于威斯康星冰期期间本地蚯蚓动物群的灭绝。自欧洲殖民者到来以来，欧洲蚯蚓一直在入侵北美生态系统，它们的存在通过改变土壤结构、养分循环、植物生长以及土壤微生物和动物的组成和功能，对当地动植物产生了深远的影响。尽管欧洲蚯蚓具有生态相关性和生态系统工程师的功能，但它们在北美与人类有关的扩散、遗传变异和适应的重要性几乎没有得到调查。该项目旨在通过分析欧洲蚯蚓在大陆尺度上的种内遗传变异和在地方和区域尺度上的种群遗传，来调查欧洲蚯蚓对北美生态系统的入侵。本文以两种最常见的欧洲入侵蚯蚓——陆生蚓（Lumbricus terrestris）和风疹蚓（Lumbricus rubellus）为研究对象，它们具有不同的生活史、传播能力和摄食策略，是研究入侵过程的理想生物。这允许区分由人为使用、移动性和对非生物因素的耐受性引起的遗传模式。该项目旨在回答北美的非本地蚯蚓种群是否由于从许多来源引进而具有遗传多样性，还是由于少数遗传谱系的优势而具有遗传同质性，并打算确定殖民路线。此外，还研究了夏季干旱和冬季严寒等生态因子对蚯蚓种群遗传构成的影响。该项目被分成三个主要工作包（wp）。WP1研究陆地乳杆菌和风疹乳杆菌在大陆尺度上的遗传多样性和扩展途径。WP2探讨了最近人类在区域和局部尺度上介导的扩散作用，以及这两种生态不同的蚯蚓物种之间迁移和基因流动的差异。WP3利用田间微生态系统和分子标记研究陆地草对环境因子的适应性。蚯蚓代表了一个迄今为止未被重视的模型，通过结合分子方法和互补的实地实验来回答入侵生物学的一般问题。

Large parts of North America are devoid of native earthworm species, presumably due to extirpation of the indigenous earthworm fauna during the Wisconsinan Glaciation. European earthworms have been invading North American ecosystems since the arrival of European settlers, and their presence has profound effects on the native flora and fauna by altering soil structure, nutrient cycling, plant growth, and the composition and functions of soil microorganisms and animals. Despite their ecological relevance and their functioning as ecosystem engineers, the importance of human-related dispersal, genetic variability and adaptation of European earthworms in North America is hardly investigated.The proposed project intends to investigate the invasion of European earthworms into North American ecosystems by analyzing intraspecific genetic variability at the continental scale and population genetics at local and regional scales. We focus on two of the most common invasive European earthworm species, Lumbricus terrestris and Lumbricus rubellus, representing ideal organisms to investigate invasion processes as they possess different life-histories, dispersal abilities and feeding strategies. This allows differentiation between genetic patterns caused by anthropogenic use, mobility and tolerance to abiotic factors.The project aims at answering if non-native earthworm populations in North America are genetically diverse due to introduction from many sources or genetically homogenous due to the dominance of few genetic lineages, and intends to identify colonization routes. Further, the importance of ecological factors, such as drought in summer and freezing in winter, as drivers of the genetic constitution of earthworm populations is investigated. The project is separated into three main work packages (WPs). WP1 investigates the genetic diversity and expansion routes of L. terrestris and L. rubellus at the continental scale. WP2 explores the role of recent human mediated dispersal at regional and local scales as well as differences in migration and gene flow between these two ecologically different earthworm species. WP3 investigates the adaptability of L. terrestris to environmental factors using field mesocosms and molecular markers. Earthworms represent a heretofore underappreciated model for answering general questions in invasion biology by combining molecular methods and complementary field experiments.