臺灣與鄰近島嶼蓮葉桐族群遺傳結構之研究

Population Genetic Variation of Hernandia nymphiifolia Among Taiwan and Nearby Islands

鄧書麟(Shu-Lin Deng) ； 傅昭憲(Chao-Hsien Fuh) ； 張坤城(Kun-Cheng Chang) ； 郭育妏(Yu-Wen Kuo) ； 黃瓊逸(Chiung-Yi Huang)

《台灣農學會報》 18卷1期 (2017/03) Pp. 43-60

https://doi.org/10.6730/JAAT.201703_18(1).0004

摘要

蓮葉桐 (Hernandia nymphiifolia (Presl) Kubitzki) 為蓮葉桐科 (Hernandiaceae) 蓮葉桐屬植物，分佈於舊熱帶地區。在臺灣與鄰近島嶼中見於恆春半島、蘭嶼、綠島及日本西表島等地，屬半紅樹類 (non-exclusive mangrove) 植物，數量稀少。本種為優良防風樹種，加上樹姿優美故為庭園觀賞植物。種子富含油質可提煉為肥皂及橡膠代用品原料，樹枝的化學成分具很強的抗腫瘤活性，故兼具經濟及國土保安價值。本研究以取自臺灣、蘭嶼、綠島與日本西表島等共4 個地區，8 個族群，計76 個蓮葉桐樣株，應用簡單序列重覆分子指紋技術(Inter-simple sequence repeat, ISSR)，來探討臺灣與鄰近島嶼蓮葉桐族群之遺傳結構及族群間親緣關係，共使用7 個引子，獲得119 個條帶，其中多型性條帶有74 個 (62.18%)，單型性條帶有45 個 (38.82%)。POPGENE 分析結果總基因歧異度 (H) 為0.1790，族群間之遺傳分化係數 (Gst) 為0.6838，基因流 (Nm) 為0.1156。經族群分子變方分析 (Analysis of Molecular Variance, AMOVA) 結果，島嶼間之變方成分為70.78% (p ＜ 0.001)，島嶼內族群間之變方成分為5.80% (p ＜ 0.001)，族群內個體間之變方成分為23.41% (p ＜ 0.001)，顯示在不同島嶼與族群間已有分化趨勢。依歸群及主座標分析結果可區分為3 大群，其中臺灣族群為一群、蘭嶼與綠島的族群為另一群、日本西表島的族群自成一群。依Mantel test 結果顯示，族群間地理距離與遺傳距離並不顯著 (r ＝ 0.83，p ＝ 0.99)，推測應受島嶼區隔與人為破壞之影響，導致基因流受阻所致。由於蓮葉桐族群總體的基因歧異度相較於其他濱海植物相對較低，建議除應採取就地保育之措施來保護蓮葉桐所有族群外，另需透過遷地保育措施來保存。

關鍵字

蓮葉桐 ； 族群遺傳變異 ； 基因歧異度 ； 基因流 ； 遺傳距離

並列摘要

Hernandia nymphiifolia (Presl) Kubitzki belongs to the genus Hernandia (Hernandiaceae). It is widely distributed in the old tropical region and can be seen in Taiwan and its nearby islands, such as Hengchun Peninsula, Lanyu, Green Island and Iriomote Island. The amount of this species of non-exclusive mangrove is rather limited now. This species, as an excellent coastal windbreak tree, plus its good shape makes it suitable as an ornamental plant. Besides, its seed, which is rich in oil, can be extracted as a substitute material for soap and rubber. Moreover, chemical constituents found in its branch show strong antineoplasic activity. Generally, this species possesses high landcare and economic values. In this study, ISSR markers were used for studying the genetic variation and population genetic structure of 76 individuals sampled from eight populations in Taiwan, Lanyu, Green-Island and Iriomote-Island (Japan). A total of seven primers were used and 119 polymorphic sites were detected. Among them, 74 bands were polymorphic (62.18%), while 45 band were monomorphic (38.82%). POPGENE analysis revealed total gene diversity (H) was 0.1790 and genetic differentiation index (Gst) was 0.6838, while gene flow index (Nm) was 0.1156. Analysis of molecular variance (AMOVA) revealed the variance component between population regions was 70.78% (p ＜ 0.001), and populations within regions were 5.80% (p ＜ 0.001), and among individuals within the population was 23.41 (p ＜ 0.001). The result indicated significant genetic differentiation among islands and among populations within islands. UPGMA cluster analysis and principal coordinates analysis (PCoA) showed they were divided into three groups, which were the Hengchun Peninsula group, the Lanyu and Green Island group, and the Iriomote Island group. The Mantel test showed no significant relation between genetic and geographic distance (r ＝ 0.83, p ＝ 0.99). The result may have been caused by geographic segmentation and man-made damage, so the gene flow among populations was relatively restricted, and populations on different islands also showed significant genetic differentiation. To sum up, the genetic diversity of H. nymphiifolia is relatively low when compared to other coastal plants. Based on the above findings, it is suggested not only in-situ but also ex-situ conservation approaches are necessary for this species.

並列關鍵字

Hernandia nymphiifolia (Presl) Kubitzki ； Population genetic variation ； Genetic diversity ； Gene flow ； Genetic distance

參考文獻

鄧書麟、呂福原、沈勇強、鄭正義、張坤成。2008b。臺灣與鄰近島嶼水芫花族群遺傳多樣性研究。中華林學季刊 41 (2):149-164。

林佳芸、曾彥學、曾喜育、王偉、呂金誠。2016。金門浦邊地區海茄苳族群結構之研究。中華林學季刊 49 (3):211-228。

Angdlique, Q. and M. Debusschea. 2000. Seed dispersal and germination patterns in a rare Mediterranean island endemic (Anchusa crispa Viv. Boraginaceae) Acta Oecol. 21(6):303-313.

Carlos, J., B. C. Emerson, and P. Oromi. 2000. Colonization and diversification: Towards a phylogeographics synthesis for the Canary Islands. Tree 15(3):104-109.

Clarke, P. J. 1995. The population dynamics of the mangrove Avicennia marina , demographic synthesis and predictive modeling. Hydrobiologia 295:83-88.