摘要 玉山箭竹(Yushania niitakayamensis (Hay.)Keng f.)主要分布在2500公尺以上山區,為台灣高海拔山區廣泛分布物種,本研究以葉綠體DNA之trnT-trnL、trnT-trnD基因區間片段來檢測台灣及大陸鄰近地區的族群遺傳變異,並探討其親緣地理關係,結果發現由於地理隔離使福建戴雲山與台灣族群的分化指數達0.6944,武夷山與台灣族群亦有0.505,而台灣不同山脈之玉山箭竹並沒有因河流谷地的隔離而產生分化,其中中央山脈與玉山山脈遺傳分化指數為0.00887、玉山山脈與雪山山脈為0.00381、雪山山脈與玉山山脈為0.00703,分化指數均低,但北部的北插天山與南部的塔關山和其他族群之遺傳分化指數則達0.5813、0.4897,最南部的大里力山更呈現出族群內無變異之僵化現象。台灣地區各族群基因流傳順暢,Nm平均值達7。親緣關係的分析探討了台灣地區可能之族群擴張路徑,發現台灣地區族群親緣樹有地理結構存在,此外亦發現冰期對玉山箭竹造成嚴重瓶頸效應(bottlenect effect),冰期結束後族群快速擴張,形成星狀親緣樹之結構,同時亦發現玉山箭竹有二次入侵的可能性。 本研究在核DNA的ITS片段探討遺傳變異的過程中,首次發現玉山箭竹葉子有內生真菌存在。
Abstract Yushania niitakayamensis (Hay).Keng f is growing in 2000-3500m elevation mountain areas in Taiwan. To investigate the population genetic diversity and phylogeography of Y. niitakayamensis in Taiwan and Fujian , the intergenic spacers of chloroplast DNA ( trnD~trnT、trnT~trnL) were sequenced. In this study , cpDNA sequences were applied to detect the genetic variation of 16 populations (13 in Taiwan, 2 in Wuyishan, 1 in Daiyunshan). The results shown that, the genetic differentiation (FST=0.6944) was high among the populations of Daiyunshan and Taiwan, and 0.505 among Wuyishan and Taiwan. The genetic differentiation was low between the mountain ranges in Taiwan (FST=0.00887,0.00381,0.00703). Only the one northern and two sourthern populations in Taiwan had high genetic differentiation (FST=0.5831,0.4897,one is fixed). The average genetic flow was high in the populations in Taiwan (Nm=7). The phylogeographic pattern shown in the median-joining network that reconstructed the possible colonized routes of Y. niitakayamensis. Several evidences suggested that glaciation caused strictly bottlenect effect to Y. niitakayamensis. There was also evidence that maybe least twice invasion of Y. niitakayamensis in Taiwan. Using the internal transcribed spacer (ITS) DNA to investigate the population genetic diversity , we found fungal endophytes of Y. niitakayamensis.