Data from: Pathways of cryptic invasion in a fish parasite traced using coalescent analysis and epidemiological survey

Introduced species have the potential to outperform natives via the introduction of new parasites to which the native ecosystem is vulnerable. Cryptic diversity within an invasive species can obscure invasion patterns and confound proper management measures. The aim of this study is to use coalescent theory based methodology to trace recent routes of invasion in populations of Ligula intestinalis, a globally distributed fish parasite possessing both native and recently introduced populations in North Africa. Molecular analyses of mitochondrial DNA discerned a pronounced genetic divergence between introduced and native populations. Distribution of mitochondrial haplotypes demonstrated common origin of European populations with North African parasites sampled from introduced fish species in Tunisia. To test the suggested pathway of introduction, microsatellite data were examined in a model-based coalescent analysis using the software MIGRATE, where Europe to Tunisia direction of migration was favoured over alternative hypotheses of gene flow. Specificity of Tunisian populations to different host species was assessed in an epidemiologic survey confirming prevailing host-based division between introduced and native parasites in North Africa. This approach combining advanced analysis of molecular markers with host-specificity data allows revealing the evolution of host-parasite interactions following biological invasion and provides basis for devising future management measurements.

外来物种可通过引入本地生态系统所易感的新型寄生虫，获得相较于本地物种的竞争优势。入侵物种内部的隐蔽多样性（cryptic diversity）会掩盖入侵模式，干扰合理的管理措施制定。本研究旨在采用基于溯祖理论（coalescent theory）的分析方法，追踪舌状绦虫（Ligula intestinalis）种群的近期入侵路径——该物种是全球分布的鱼类寄生虫，在北非地区同时存在本地种群与新近入侵的种群。对线粒体DNA（mitochondrial DNA）的分子分析显示，入侵种群与本地种群之间存在显著的遗传分化。线粒体单倍型（haplotype）的分布特征表明，欧洲种群与从突尼斯境内入侵鱼类体内分离的北非寄生虫具有共同起源。为验证所提出的入侵路径，研究团队借助MIGRATE软件开展基于模型的溯祖分析，对微卫星（microsatellite）数据进行检验，结果支持欧洲向突尼斯的迁移路径，而非其他基因流相关假说。通过流行病学调查评估了突尼斯种群对不同宿主物种的宿主特异性，结果证实北非地区的入侵寄生虫与本地寄生虫之间存在基于宿主类群的显著分化。本研究将分子标记的高级分析方法与宿主特异性数据相结合，揭示了生物入侵后宿主-寄生虫相互作用的演化历程，为制定未来的寄生虫管理策略提供了科学依据。