Data from: Evidence for low-level hybridization between two allochronic populations of the pine processionary moth, Thaumetopoea pityocampa (Lepidoptera: Notodontidae)

Divergence between populations sharing the same habitat can be initiated by different reproductive times, leading to allochronic differentiation. A spatially localized allochronic summer population (SP) of the pine processionary moth Thaumetopoea pityocampa, recently discovered in Portugal, occurs in sympatry with the local winter population (WP). We examined the level of genetic differentiation between the two populations and estimated the current gene flow within the spatial framework of their co-occurrence. Mitochondrial data indicated that the two sympatric populations were genetically closer than other WP populations. Conversely, microsatellite genotyping uncovered greater differentiation between the two sympatric populations than between allopatric ones. While male trapping confirmed that reproduction of SP and WP occurred at distinct times, clustering approaches demonstrated the presence of a few LateSP individuals emerging within the WP flight period, although genetically identified as SP. We also identified rare recent hybridization events apparently occurring mainly in the margins of the current SP range. The ongoing gene flow detected between the ancestral and the emerging allochronic populations revealed an incomplete reproductive isolation, which must therefore be taken into account and integrated with studies focussed on ecological drivers, so that a complete understanding of the ongoing speciation process might be achieved.

栖息环境相同的种群间的分化，可由繁殖时间的差异触发，进而导致异时分化（allochronic differentiation）。近期在葡萄牙发现的定域分布的松异舟蛾（Thaumetopoea pityocampa）异时性夏季种群（SP），与当地的冬季种群（WP）呈同域共存状态。本研究检测了这两个种群间的遗传分化水平，并在二者共同分布的空间框架内评估了当前的基因流（gene flow）。线粒体数据显示，这两个同域种群的遗传亲缘关系较其他冬季种群更为紧密。与之相反，微卫星基因分型（microsatellite genotyping）结果却表明，该同域种群间的分化程度高于异域种群间的分化水平。雄虫诱捕实验证实，夏季种群与冬季种群的繁殖时间存在显著差异；聚类分析方法（clustering approaches）的结果则显示，存在少量晚夏季种群（LateSP）个体在冬季种群的成虫飞行期内羽化，但经遗传鉴定其归属为夏季种群。本研究还发现了罕见的近期杂交事件，这类事件主要发生在当前夏季种群分布范围的边缘区域。本研究在祖先种群与新兴异时种群之间检测到持续存在的基因流，表明二者的生殖隔离（reproductive isolation）尚未完全形成。因此，在聚焦生态驱动因子的相关研究中，必须将该现象纳入考量并予以整合，从而实现对当前正在进行的物种形成（speciation）过程的完整认知。