我們利用台灣特有種短腹幽蟌（Euphaea formosa），以分子標記粒線體細胞色素氧化?第二段（COII）及核醣體基因間未編碼的區間（ITS），來探討其現今的族群遺傳結構，與歷史上發生的地理事件和其生物特性之間的關係。結果顯示族群間有很大的遺傳交流，並且在COII的親緣分析中發現兩個不同的系群。COII西部系群的遺傳結構很顯著地受地理距離所隔離，且它們進入台灣的原因可能與最近一次冰河事件有很大的關係。利用COII以貝氏天際線點圖（BSP）及不符合分佈（mismatch distribution）分析過去的族群量變化指出，最近族群量擴張的現象。此外，COII廣佈系群及ITS所有個體的Tajima’s D與Fu’s FS都為顯著的負值，這一結果與星型的網路分析兩者都代表著族群經歷過擴張事件。而這一次的擴張事件與更新世晚期有時間上的相關。推論族群擴張現象可能與當時陸地面積增加所導致棲息地增加有關。 We used an endemic Formosan damselfly, Euphaea formosa (Insecta: Odonata: Euphaeidae) in Taiwan to investigate the pattern of contemporary population genetic structure using both mitochondrial cytochrome oxidase II (COII) and nuclear internal transcribed spacer (ITS) genes, and to discuss geohistorical events and life history characteristics that may have contributed to the observed patterns. Our results suggested that there was substantial gene flow among populations. Two distinct haplotype clades, one western restricted and one widespread clade, were identified based on COII phylogeny. The COII western clade, which showed a significant isolation by distance pattern, may colonize Taiwan due greatly to recent glacial events. Historical demography estimated using Bayesian skyline plot (BSP) and mismatch distribution showed a pattern of recent population expansion. Significant negative Tajima’s D and Fu’s FS values coupled with star-like networks of COII widespread clade and ITS also indicate population expansion. We conclude that the colonization and demographic expansion of damselfly populations were likely the result of increased available habitats during late Pleistocene.
