Data from: Population genetic structure of the western cherry fruit fly Rhagoletis indifferens (Diptera: Tephritidae) in British Columbia, Canada

1. Population connectivity and movement are key ecological parameters influencing the impact of pests, and are important considerations in control strategies. For many insects, these parameters are difficult to assess directly, although they may be assessed indirectly using population genetic data. 2. We used microsatellite markers to examine population genetic structure of the western cherry fruit fly, the main pest of cherry crops in western North America, in British Columbia, Canada, and make inferences about connectivity and potential for movement among populations. 3. Comparing populations from four geographical regions (separated by up to approximately 400 km), we found significant genetic differentiation both among and within regions. Using populations as the units of analysis, we observed significant isolation by distance (IBD) at larger spatial scales but not below approximately 20 km. By contrast, using individual flies as the units of analysis, we found significant IBD at scales as small as < 100 m. We saw no evidence of genetic differentiation among populations sampled from different species/varieties of plants. 4. Our results suggest that the movement of individual flies is limited, although high levels of gene flow are maintained at scales of up to 20 km, possibly through combined effects of stepping-stone gene flow and large population sizes.

1. 种群连通性与扩散是影响害虫危害程度的核心生态学参数，也是害虫防控策略制定时需重点考量的关键因素。对于多数昆虫而言，这类参数难以直接测定，但可借助种群遗传数据进行间接推断。
2. 本研究以北美西部樱桃作物的主要害虫——西部樱桃实蝇为研究对象，利用微卫星标记（microsatellite markers）对加拿大不列颠哥伦比亚省的该虫种群遗传结构进行解析，并据此推断种群间的连通性与扩散潜力。
3. 通过对比4个地理区间（最大间距约400公里）的种群，我们发现区域间及区域内均存在显著的遗传分化。以种群为分析单元时，仅在较大空间尺度上观测到显著的距离隔离（isolation by distance，IBD）效应，而在约20公里以下的尺度中未发现该现象；与之相反，以单个实蝇为分析单元时，在低至小于100米的尺度上均能检测到显著的距离隔离效应。此外，未发现取自不同植物物种或品种的种群间存在遗传分化。
4. 本研究结果表明，单个实蝇的扩散能力有限，但在最大20公里的尺度内仍可维持较高水平的基因流，这一现象可能是踏脚石基因流与种群规模庞大共同作用的结果。