The predatory cladoceran Bythotrephes is one of North America’s most successful and impactive invasive species in freshwater plankton communities. The taxonomic status of the genus Bythotrephes Leydig, 1860 (Crustacea: Cladocera: Cercopagididae) has remained unclear and a subject of intensive debate for over 150 years. We applied an integrative taxonomy approach with multi-gene analysis (mitochondrial COI and 12S genes, and nuclear 18S and 28S genes) on 80 individuals (representing at least four morphospecies) from various regions spanning the genus distribution (North America, Europe, and Asia) to resolve the taxonomic status of species within Bythotrephes. The results of our study strongly support the hypothesis of a single species—Bythotrephes longimanus Leydig, 1860, and ecological morphs should be accepted as junior synonyms. Our work also elucidates the very recent radiation of Bythotrephes, which may have begun rapidly and parallel during the Late Pleistocene, or even after the last glaciation. Finally, we provide a comprehensive biogeographic reconstruction of Bythotrephes dispersal within the Holarctic realm. Europe likely served as a dispersal centre for Bythotrephes from where they spread relatively recently (possibly, less than 10 kyr) and we distinguish five possible dispersal events in its evolutionary history.

中文翻译：

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捕食性浮游水蚤中快速平行的晚更新世/全新世形态辐射：Bythotrephes （Cladocera： Cercopagididae） 的案例


掠食性枝角动物 Bythotrephes 是北美淡水浮游生物群落中最成功和最具影响力的入侵物种之一。Bythotrephes Leydig， 1860 属（甲壳纲：Cladocera：Cercopagididae）的分类地位一直不清楚，并且是一个 150 多年来激烈争论的主题。我们对来自属分布不同地区（北美、欧洲和亚洲）的 80 个个体（代表至少四种形态物种）应用了多基因分析（线粒体 COI 和 12S 基因，以及核 18S 和 28S 基因）的综合分类方法，以解决 Bythotrephes 中物种的分类地位。我们的研究结果有力地支持了一个物种的假设——Bythotrephes longimanus Leydig， 1860，生态形态应该被接受为初级同义词。我们的工作还阐明了 Bythotrephes 最近的辐射，它可能在晚更新世甚至在最后一次冰期之后迅速而平行地开始。最后，我们提供了 Bythotrephes 在 Holarctic 领域内扩散的全面生物地理重建。欧洲可能是 Bythotrephes 的扩散中心，它们最近才从那里传播（可能不到 10 kyr），我们在其进化史中区分了五种可能的扩散事件。