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.

共享相同栖息地的种群间的分化，可由繁殖时间的差异启动，进而引发异时分化（allochronic differentiation）。近期在葡萄牙发现的、空间分布局限的松异舟蛾（Thaumetopoea pityocampa）异时性夏季种群（SP），与当地的冬季种群（WP）呈同域分布（sympatry）状态。本研究检测了这两个种群间的遗传分化水平，并基于二者同域共存的空间背景，估算了当前的基因流（gene flow）水平。线粒体数据（mitochondrial data）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）结果表明，这两个同域种群间的分化程度高于异域种群（allopatric population）间的分化程度。尽管雄虫诱捕（male trapping）实验证实了SP与WP的繁殖时间存在显著差异，但聚类分析方法（clustering approaches）揭示，存在少量晚发SP个体（LateSP）会在WP的成虫发生期内羽化，尽管其遗传背景被鉴定为SP。本研究同时发现了少量近期发生的杂交事件，这类事件主要集中在当前SP种群分布范围的边缘区域。在祖先种群与新兴异时种群间检测到的持续基因流，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，必须纳入该因素，以实现对当前物种形成（speciation）过程的全面解析。