大眼華鳊親緣地理與族群遺傳結構之研究

Abstract

本研究利用粒線體DNA研究大眼華鯿之親緣地理與族群遺傳結構，Tajima’s D統計上呈現顯著負值，高的平均單型多樣性(h=0.999)與低核苷酸歧異值(π=0.009)顯示大部分的族群歷經族群擴張。族群間分化指數平均為0.583，顯示族群間具較低的基因交流而呈現高度分化。以聚類分析(neighbor-joining)法重建親緣關係圖，但並無法明顯再依地理區或河系分群，顯示大眼華鯿群正處於譜系排序(lineage sorting)的狀態。根據NCA法分析，顯示大眼華鯿族群曾經歷過去破碎化事件與長距離拓殖等歷史事件，在網狀親緣關係(network)的分析中發現淡水河與閩江的關係最為密切，顯示淡水河的大眼華鯿應由閩江擴散而來。

The phylogeograhical and population genetic structures of Sinibrama macrops were investigated based on genetic eiversity of mtDNA. Significantly negative Tajima’s D statistics based on mtDNA suggest that mos populations originated form a small number of founders followed by demographic expansion. High haplotype diversity (h=0.999) and low nucleotide diversity (π=0.009) may be attributed to expansion after a period of lwo effective population size. MtDNA analyses revealing evident geographical structuring suggest limited gene flow between populations (FST=0.583). Neighbor-joining tree of mtDNA identified one lineage suggest all population revealing lineage sorting. Nested clade analyses revealing revealing significant associations between genetic structure and geographical division identify past fragmentation and/or Long-distance colonization as major phylogeographical events that shaped that geographical distribution of this species. According the nested clade analyses, the populations of the DanShui River and the Min River had the closed relationship. This result suggested the populations of the DanShui River would be originated form the Min River.