地理隔離在過去一直被認為是推動種化的主要力量。異域種化模式強調地理屏障和阻斷基因交流對於族群分化的重要性。在異域種化的模式下，基因交流被認為是種化的阻礙。對於過去有多少基因交流發生在分化中的野生族群或物種目前仍然不明。本研究我們利用兩個粒線體和十個核基因來估算兩對姊妹種幽蟌屬豆娘—E. formosa + E. yayeyamana以及E. decorata + E. ornata—在過去種化進行時的基因交流程度。根據cox2和arr基因所重建的親緣關係顯示E. formosa + E. yayeyamana以及E. decorata + E. ornata為支持度高的姐妹種。在E. formosa + E. yayeyamana和E. decorata + E. ornata這兩對的多基因座分析結果皆棄卻狹義的地理隔離模式。在E. formosa和E. yayeyamana之間，我們發現中等至大量的雙向基因交流，但在E. decorata和E. ornata之間沒有太多的基因交流證據。E. decorata和E. ornata的分化時間估計約為 0.511個百萬年前，這個時間晚於E. formosa和E. yayeyamana的分化時間 (1.145個百萬年前)。分析結果指出有基因交流的種化模式，最能解釋在E. formosa和E. yayeyamana族群內所觀察到的DNA序列變異，而沒有基因交流的異域種化模式則較適合描述E. decorata和E. ornata的分化。 Geographic isolation has been proposed as a major force in speciation. Allopatric mode of speciation emphasizes the prominent role of physical barriers and restriction of gene flow on population divergence. Under allopatric model, gene flow is considered as an impediment for speciation. The question of how much historical gene flow has occurred in diverged natural populations and species is largely unknown. In this study, we investigated the level of historical gene flow during the speciating process of two sibling species pairs of Euphaea damselflies, E. formosa + E. yayeyamana and E. decorata + E. ornata, using two mitochondrial and ten unclear loci. The reconstructed species phylogeny based on cox2 and arr genes indicated that E. formosa + E. yayeyamana, and E. decorata + E. ornata, are both valid sister species pairs. The results of multilocus analyses rejected the strict isolation model in E. formosa and E. yayeyamana, and E. decorata and E. ornata. Moderate to large two directional gene flows were detected between E. formosa and E. yayeyamana, but there is little evidence of gene flow between E. decorata and E. ornata. The divergence time of E. decorata and E. ornata was estimated at approximately 0.511 Mya, which was more recent than the split of E. formosa and E. yayeyamana (1.145 Mya). We concluded that the model of speciation with gene flow best describe the observed sequence variation in E. formosa and E. yayeyamana, whereas the model of allopatric speciation without gene flow is more appropriate for E. decorata and E. ornata.
