Data from: Rapid movement and instability of an invasive hybrid swarm

Unstable hybrid swarms that arise following the introduction of non-native species can overwhelm native congeners, yet the stability of invasive hybrid swarms has not been well documented over time. Here we examine genetic variation and clinal stability across a recently formed hybrid swarm involving native blacktail shiner (Cyprinella venusta) and non-native red shiner (C. lutrensis) in the Upper Coosa River basin, which is widely considered to be a global hotspot of aquatic biodiversity. Examination of phenotypic, multilocus genotypic, and mitochondrial haplotype variability between 2005 and 2011 revealed that the proportion of hybrids has increased over time, with more than a third of all sampled individuals exhibiting admixture in the final year of sampling. Comparisons of clines over time indicated that the hybrid swarm has been rapidly progressing upstream, but at a declining and slower pace than rates estimated from historical collection records. Clinal comparisons also showed that the hybrid swarm has been expanding and contracting over time. Additionally, we documented the presence of red shiner and hybrids farther downstream than prior studies have detected, which suggests that congeners in the Coosa River basin, including all remaining populations of the threatened blue shiner (Cyprinella caerulea), are at greater risk than previously thought.

外来物种引入后形成的不稳定杂交种群集群（hybrid swarm）可对本土同属物种构成生存竞争压制，但目前学界尚未对入侵性杂交种群集群的长期稳定性开展充分的长期追踪与记录工作。本研究针对被广泛视为全球水生生物多样性热点区域的库萨河上游流域，对其中新近形成的、涉及本土黑尾闪鲦（blacktail shiner, Cyprinella venusta）与外来红闪鲦（red shiner, C. lutrensis）的杂交种群集群，开展遗传变异与渐变群（cline）稳定性分析。通过对2005年至2011年采集样本的表型、多位点基因型（multilocus genotypic）及线粒体单倍型（mitochondrial haplotype）变异进行分析，结果显示杂交个体占比随时间持续上升，在采样末期的全部采集个体中，超过三分之一均表现出遗传混合特征。不同时期的渐变群对比结果表明，该杂交种群集群正快速向河流上游扩散，但其扩散速率不仅低于历史采集记录的估算值，且呈逐渐放缓的趋势。渐变群对比同时显示，该杂交种群集群的分布范围随时间呈现出扩张与收缩交替的动态变化。此外，本研究在较以往研究更靠下游的区域发现了红闪鲦与杂交个体的分布，这意味着库萨河流域内的同属物种——包括所有现存的受威胁蓝闪鲦（blue shiner, Cyprinella caerulea）种群——所面临的生存风险远高于此前预估。