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

北美的大部分地区缺乏本土蚯蚓物种，这可能是由于威斯康星冰川期间本土蚯蚓动物群的灭绝所致。自欧洲定居者到来以来，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，但几乎没有人研究欧洲蚯蚓在北美与人类相关的传播、遗传变异和适应的重要性。拟议的项目旨在通过分析大陆尺度的种内遗传变异和当地和区域尺度的种群遗传学来调查欧洲蚯蚓入侵北美生态系统的情况。我们专注于欧洲最常见的两种入侵蚯蚓--陆生蚯蚓和陆生蚯蚓，它们具有不同的生活史、传播能力和取食策略，是研究入侵过程的理想生物。这使得由人为利用、迁移性和对非生物因素的耐受性造成的遗传模式得以区分。该项目旨在回答北美的非本地蚯蚓种群是由于来自多个来源的引入而遗传多样化，还是由于少数遗传谱系的优势而遗传同质性，并打算确定殖民路线。此外，还研究了夏季干旱和冬季寒冷等生态因素作为蚯蚓种群遗传构成的驱动因素的重要性。该项目分为三个主要工作包(WPS)。WP1在大陆尺度上调查了陆生乳杆菌和赤潮乳杆菌的遗传多样性和扩展途径。WP2探讨了最近人类在区域和地方尺度上的传播所起的作用，以及这两个生态上不同的蚯蚓物种在迁徙和基因流动方面的差异。WP3利用田间中隔和分子标记研究了陆生乳杆菌对环境因子的适应性。蚯蚓代表了一种迄今未得到重视的模型，通过结合分子方法和互补的田间实验来回答入侵生物学中的一般问题。

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.