Data from: Low genetic diversity but strong population structure reflects multiple introductions of western flower thrips (Thysanoptera: Thripidae) into China followed by human-mediated spread

Historical invasion scenarios based on observational records are usually incomplete and biased, but these can be supplemented by population genetic data. The western flower thrips (WFT), Frankliniella occidentalis, invaded China in the last 13 years and has rapidly become one of the most serious pests in the country. To assess whether this invasion involved a single event or multiple events, we examined patterns of genetic diversity and population structure of WFT across 12 Chinese populations and a native US population based on mitochondrial DNA and/or 18 microsatellite loci. The average allelic richness and haplotype diversity in Chinese populations were significantly lower than in a population from its native range. The distribution of mitochondrial haplotypes suggested multiple independent invasions of WFT into China, including two invasions into the Beijing region. Based on microsatellite data, two distinct clusters were identified, with both of them splitting further into two clusters; in the Beijing region, the microsatellite data also provided evidence for two introductions. Both the absence of isolation by distance and the fact that distant populations were similar genetically suggest patterns of WFT movement linked to human activities. Our study therefore suggests multiple introductions of WFT into China and human-assisted spread.

基于观测记录构建的历史入侵场景通常存在不完备性与偏倚性，但可通过种群遗传学数据进行补充完善。西花蓟马（western flower thrips, WFT，*Frankliniella occidentalis*）于近13年间入侵我国，并迅速成为国内危害最严重的害虫之一。为评估该入侵过程系单次事件还是多次独立事件，我们基于线粒体DNA及/或18个微卫星位点，对我国12个西花蓟马种群及美国本土1个种群的遗传多样性模式与种群结构开展了分析。我国种群的平均等位基因丰富度与单倍型多样性均显著低于其本土分布区种群。线粒体单倍型的分布格局表明，西花蓟马曾多次独立入侵我国，其中北京地区存在两次入侵事件。基于微卫星数据分析，我们鉴定出两个显著分化的聚类群，且两个聚类群均可进一步划分为两个亚聚类群；在北京地区，微卫星数据同样佐证了两次引种事件。既未检测到距离隔离效应，且地理远隔种群的遗传相似性较高，这表明西花蓟马的扩散模式与人类活动密切相关。综上，本研究表明西花蓟马多次入侵我国，并通过人类活动实现辅助扩散。