Data from: Regional divergence and mosaic spatial distribution of two closely related damselfly species (Enallagma hageni and Enallagma ebrium)

North American Enallagma damselflies radiated during the Pleistocene, and species differ mainly by reproductive structures. Although morphologically very different, Enallagma hageni and Enallagma ebrium are genetically very similar. Partitioning of genetic variation (AFLP), isolation by distance and clustering analyses indicate that these morphospecies are locally differentiated genetically. Spatial analyses show that they are rarely sympatric at local sites, and their distributions form a mosaic of patches where one is clearly dominant over hundreds of square kilometers. However, these morphospecies are also not genetically more similar when they are sympatric, indicating that hybridization is probably not occurring. Given that these morphospecies are ecologically equivalent, strong assortative mating, reproductive interference and fast post-glacial recolonization may explain the origin and maintenance of these distributional patches across eastern North America. By limiting opportunities for gene flow, reproductive interference may play an unsuspected role in accelerating genetic differentiation in the early phases of nonecological speciation.

北美原蟌属（Enallagma）蜻蛉在更新世时期发生辐射演化，其物种间的差异主要体现在生殖结构上。尽管哈氏原蟌（Enallagma hageni）与埃布瑞原蟌（Enallagma ebrium）的形态差异显著，但二者的遗传相似度极高。基于扩增片段长度多态性（AFLP）的遗传变异分区分析、距离隔离分析以及聚类分析结果表明，这两个形态种在局域尺度上存在遗传分化。空间分析显示，二者极少在局域位点实现同域分布，其分布呈现斑块镶嵌格局——在数百平方公里的范围内，其中一个物种会占据绝对优势。然而，即便二者处于同域分布状态，其遗传相似度也并未显著提升，这表明杂交事件大概率并未发生。鉴于这两个形态种在生态位上完全等价，强烈的选型交配、生殖干扰以及快速的冰后再定植过程，或可解释北美东部地区这类分布斑块的起源与维持机制。生殖干扰通过限制基因交流的机会，可能在非生态物种形成的早期阶段加速遗传分化的过程中，发挥了此前未被重视的作用。