台灣、西表島與香港銀葉樹族群遺傳多樣性之研究

Population Genetic Variation of Heritiera Littoralis among Taiwan, Iriomote-Island and Hong Kong

鄧書麟(Shu-Lin Deng) ； 呂福原(Fu-Yuan Lu) ； 許原瑞(Yen-Ray Hsui) ； 林喻東(Yui-Dung Lin) ； 吳欣瑾(Hsin-Chin Wu)

《中華林學季刊》 42卷4期 (2009/12) Pp. 503-518

https://doi.org/10.30064/QJCF.200912.0003

摘要

Heritiera littoralis is an exclusive mangrove species, which can grow in both intertidal wetland and inland. Althouth their distribution ranges widely from Africa, Asia to Australia; population size of H. littoralis decreased markedly due to overexploitation for wood and habitat destruction and face a serious threat. In this study, the genetic variation and population structure of 60 individuals sampled from 6 populations of H. littoralis in main island of Taiwan and its nearby islands were studied using ISSR markers. POPGENE analysis revealed that total gene diversity (H) was 0.2888 and genetic differentiation index (Gst) was 0.2742, while gene flow index (Nm) was 0.6618, which indicated that the genetic differentiation was high among populations. In conclusion, the gene flow among populations was relatively restricted. Geographic segmentation and ocean current’s flow direction may be influential factors to the genetic differentiation among these populations. UPGMA cluster analysis showed that they could be divided into three groups: Taiwan group, Hong Kong group, and the group of Iriomote-island. Taiwan populations had a closer genetic distance to Hong Kong population. Analysis of molecular variance (AMOVA) revealed that the variance component among populations was 38.17% (p＜0.001), and among individuals within population was 61.87% (p＜0.001). The result indicated significant genetic differentiation among regions and among population within regions; however, most variation existed among individuals within populations. In addition, there was positive but not significant relation between genetic distance and geographic distance (r=0.47, p=0.13), pointing to a random distribution among populations. Based on the above results, both In-Situ and Ex-Situ conservation are necessary in preserving this species.

關鍵字

銀葉樹 ； 基因流 ； 遺傳變異 ； 遺傳距離

並列摘要

Heritiera littoralis is an exclusive mangrove species, which can grow in both intertidal wetland and inland. Althouth their distribution ranges widely from Africa, Asia to Australia; population size of H. littoralis decreased markedly due to overexploitation for wood and habitat destruction and face a serious threat. In this study, the genetic variation and population structure of 60 individuals sampled from 6 populations of H. littoralis in main island of Taiwan and its nearby islands were studied using ISSR markers. POPGENE analysis revealed that total gene diversity (H) was 0.2888 and genetic differentiation index (Gst) was 0.2742, while gene flow index (Nm) was 0.6618, which indicated that the genetic differentiation was high among populations. In conclusion, the gene flow among populations was relatively restricted. Geographic segmentation and ocean current’s flow direction may be influential factors to the genetic differentiation among these populations. UPGMA cluster analysis showed that they could be divided into three groups: Taiwan group, Hong Kong group, and the group of Iriomote-island. Taiwan populations had a closer genetic distance to Hong Kong population. Analysis of molecular variance (AMOVA) revealed that the variance component among populations was 38.17% (p＜0.001), and among individuals within population was 61.87% (p＜0.001). The result indicated significant genetic differentiation among regions and among population within regions; however, most variation existed among individuals within populations. In addition, there was positive but not significant relation between genetic distance and geographic distance (r=0.47, p=0.13), pointing to a random distribution among populations. Based on the above results, both In-Situ and Ex-Situ conservation are necessary in preserving this species.

並列關鍵字

Heritiera littoralis ； Gene flow ； Genetic variation ； Genetic distance