台灣與鄰近島嶼水芫花族群遺傳 多樣性之研究

水芫花為泛熱帶分布的海灘及岩岸第一線植物，在台灣與鄰近島嶼中見於恆春半島、小琉球、蘭嶼及綠島等地，屬半紅樹類植物。本研究以取自上述地區15個族群150株水芫花個體，應用簡單序列重覆分子指紋技術來分析台灣本島與鄰近島嶼水芫花族群遺傳結構及族群間親緣關係，計使用6個引子，得到95個多型性條帶。POPGENE分析的結果發現Nei’s族群基因歧異度（H）為0.3017，族群間之遺傳分化係數（Gst）為0.2816，基因流（Nm）為0.6378，顯示族群已具高度分化結構。由族群分子變方分析（AMOVA）結果，地區間之變方成分為7.83 %（p＜0.001），地區內族群間之變方成分是13.37 %（p＜0.001），族群內個體間的變方成分是78.79 %（p＜0.001），顯示不同島嶼與族群間已有分化趨勢，但主要遺傳變異係存於族群內個體間。歸群及主座標分析結果可分為三群，其中蘭嶼的族群為一群，恆春半島及綠島之族群組成另一群，小琉球之族群自成一群。水芫花族群間之地理距離與遺傳距離具正相關（r0.56，P0.02*），符合距離隔離模式，推測是自然散布之結果。綜言之，水芫花族群基因流傳並不暢通，不同島嶼間已有分化現象，推測為島嶼間區隔對族群間之遺傳分化產生較顯著影響。就所得族群遺傳訊息，建議宜採就地保育之措施。

Pemphis acidula is a pantropical primary species of beach and rocky shore habitats, distributed in the Hengchun Peninsula, Xiaoliuqiu, Lanyu (Orchid Island), and Ludao (Green Island) of Taiwan and its adjacent islands, and it belongs to semi-mangrove species. In this study, 150 individuals of P. acidula were sampled from 15 populations across the aforementioned regions. Simple Sequence Repeat (SSR) molecular fingerprinting was employed to analyze the genetic structure and inter-population phylogenetic relationships of P. acidula populations in mainland Taiwan and its adjacent islands. A total of 6 primers were used, yielding 95 polymorphic bands. Analysis via POPGENE revealed that Nei’s gene diversity (H) was 0.3017, the genetic differentiation coefficient among populations (Gst) was 0.2816, and the gene flow (Nm) was 0.6378, indicating that the populations have a highly differentiated structure. Results from Analysis of Molecular Variance (AMOVA) showed that 7.83% of the total genetic variation was distributed among regions (p < 0.001), 13.37% among populations within regions (p < 0.001), and 78.79% among individuals within populations (p < 0.001), indicating that differentiation has emerged among different islands and populations, but the majority of genetic variation resides among individuals within populations. Cluster analysis and Principal Coordinates Analysis (PCoA) divided the populations into three groups: Lanyu populations formed one group, Hengchun Peninsula and Ludao populations formed a second group, and Xiaoliuqiu populations constituted a third distinct group. A significant positive correlation was detected between geographic distance and genetic distance among P. acidula populations (r = 0.56, P = 0.02*), which conforms to the isolation-by-distance model, suggesting this pattern results from natural dispersal. In summary, gene flow among P. acidula populations is restricted, and differentiation has occurred among different islands, which is presumed to be caused by the significant impact of island isolation on genetic differentiation between populations. Based on the obtained population genetic information, in situ conservation measures are recommended.