Population structure of Drosophila suzukii and signals of multiple invasions in the continental United States

Drosophila suzukii, or spotted-wing drosophila, is now an established pest
in many parts of the world, causing significant damage to numerous fruit
crop industries. Native to East Asia, D. suzukii infestations started in
the United States a decade ago, occupying a wide range of climates. To
better understand invasion ecology of this pest, knowledge of
past migration events, population structure, and genetic diversity is
needed. In this study, we sequenced whole genomes of 237 individual flies
collected across the continental U.S., as well as several representative
sites in Europe, Brazil, and Asia, to identify hundreds of thousands of
genetic markers for analysis. We analyzed these markers to detect
population structure, to reconstruct migration events, and to estimate
genetic diversity and differentiation within and among the continents. We
observed strong population structure between West and East Coast
populations in the U.S., but no evidence of any population structure North
to South, suggesting there is no broad-scale adaptations occurring in
response to the large differences in regional weather conditions. We also
found evidence that repeated migration events from Asia into North America
have provided increased levels of genetic diversity, which does not appear
to be the case for Brazil or Europe. This large genomic dataset will spur
future research into the genomic adaptations underlying D. suzukii pest
activity and development of novel control methods for this agricultural
pest.

斑翅果蝇（Drosophila suzukii，英文名spotted-wing drosophila）目前已在全球多数区域成为定殖性害虫，对众多果品产业造成严重危害。该虫原产于东亚，十年前首次在美国出现种群为害，现已扩散至多种气候类型区域。为深入解析该害虫的入侵生态学机制，亟需掌握其过往迁徙事件、种群结构及遗传多样性相关信息。本研究对采集自美国本土以及欧洲、巴西、亚洲部分代表性采样点的237头斑翅果蝇个体开展全基因组测序，以此鉴定出数十万余个遗传标记用于后续分析。研究团队对这些遗传标记进行了系统分析，以检测种群结构、重构迁徙事件，并评估各大陆内部及大陆间的遗传多样性与遗传分化水平。结果显示，美国西海岸与东海岸的种群间存在显著的种群结构差异，但未检测到南北方向的种群分化，这表明该虫并未因区域气候条件的巨大差异产生大范围适应性演化。此外，团队还发现东亚种群向北美反复发生的迁徙事件提升了北美的遗传多样性水平，而巴西与欧洲种群并未出现类似现象。本研究构建的大型基因组数据集将为后续探究斑翅果蝇成灾的基因组适应性机制以及开发新型农业害虫防控手段提供重要支撑。