Genetic variation of Archangiopteris somai based on ISSR

摘要 台灣原始觀音座蓮為本島特有及稀有蕨類植物，目前只在烏來和蓮華池兩地有發現紀錄，呈現不連續的分布狀態。本研究的目的即探討被分隔的這些族群之遺傳變異。樣本分別採自烏來地區(海拔400 m)，蓮華池3號集水區(海拔650 m)及5號集水區(海拔750 m)，共採集78個樣本，以ISSR進行分子指紋分析，研究其遺傳變異。篩選125個ISSR引子，以其中的20個進行實驗，得到160條可判讀的條帶，多型性條帶有16條，佔10%，其中AM4-650 bp條帶只出現在烏來樣區之一部分個體。Nei''s種內的總歧異度指數為0.262。Shannon’s之種內的總歧異度指數為0.409，平均群內歧異度指數為0.375，佔種內的總歧異度的91.69%，而群間歧異度佔種內的總歧異度的8.31%，顯示群間歧異度比例低。族群分化係數(Gst)為0.062，基因流傳值 (Nm)為7.548。如果將蓮華池的樣區合併成同一族群時，烏來與蓮華池的Nei''s種內歧異度指數為0.262。Shannon’s平均群內歧異度指數為0.390，佔全體遺傳歧異度的95.35 %，而群間歧異度佔全體遺傳歧異度的4.65%，顯示台灣原始觀音座蓮在南北兩地的歧異度比例低。Gst為0.052，Nm為9.171。以AMOVA程式分析變方成分及顯著性檢定，樣本以二地區三樣區估算時，變方成分在地區間佔12.4%，有顯著差異(p <0.001)，在地區內樣區間佔1.6%，沒有顯著差異(p = 0.168)，在樣區內個體間佔86%，有顯著差異(p <0.001)。當樣本只分烏來和蓮華池二地區估算時，變方成分在在地區間佔13.47%，有顯著差異(p <0.001)，地區內個體間佔86.53%，有顯著差異(p <0.001)，顯示台灣原始觀音座蓮在烏來和蓮華池兩地區以ISSR分析的結果在遺傳上有顯著差異。應用DICE公式估算兩兩個體間的相似度，進行歸群分析，結果沒有因地理的距離而歸成兩群，唯此歸群之協表相關係數只有0.743，顯示此歸群分析有相當程度之扭曲。Abstract Archangiopteris somai Hayata (Marattiaceae) is a endemic rare fern of Taiwan. It is distributed discontinuously in Wulai and Lienhuachu. The purpose of this study is to study the genetic variation of these isolated populations. Seventy-eight individual samples from Wulai (400 m asl) and the No.3 (650 m asl) and No.5 (750 m asl) drainage areas at Lienhuachu were studied using ISSR markers. One-hundred and twenty-five ISSR primers were screened and among them 20 primers that produced reproducible polymorphic bands were used. Among 160 bands produced, 16 (10%) were polyporphic. Band AM4-650 was only observed in some samples of Wulai population. Nei's gene diversity index for the species was 0.262. Shannons's diversity index for the species was 0.409. Average diversity within populations was 0.375. The diversity among and within populations were 8.31% and 91.69% of the species diversity, respectively. Coefficient of gene differentiation (Gst) was 0.062 while the value of gene flow (Nm) was 7.548. These results indicated low population differentiation in this species. When two sampling sites at Lienhuachu were combined as a population, Shannon's average diversity whithin populations was 0.390. The diversity among and within populations were 4.65% and 95.35% of the species diversity, respectively. Gst was 0.052 while the value of gene flow was 9.171. These results indicated low differentiation between Wulai and Lienhuachu populations. The analysis of molecular variance (AMOVA) revealed that, when samples were divided into two regions and three populations, the variance components among regions, among populations within regions, and among individuals within populations were 12.4% (p<0.001), 1.60% (p=0.168) and 86.00% (p<0.001) of the total variance, respectively. When samples were divided into Wulai and Lienhuachu populations only, the variance components among populations and among individuals within populations were 13.47% (p<0.001) and 86.53% (p