玉山杜鵑複合群物種於更新世冰期過後之族群退縮與物種分歧

Postglacial population bottleneck and species divergence in Rhododendron pseudochrysanthum species complex

梁博凱

指導教授 ： 黃士穎

國立臺灣師範大學/理學院/生命科學研究所/碩士(2011年)

摘要

玉山杜鵑複合群的成員包括紅星、南湖、玉山、森氏杜鵑，均為台灣特有種，形態相似並且分佈的海拔也相當接近。過去的研究發現玉山杜鵑複合群為單一起源，也發現族群過去有擴張的歷史。本研究目的是以遺傳學的方法研究玉山杜鵑複合群在氣候變遷之後族群破碎化的情形下受到族群縮小的影響。本研究使用微衛星DNA片段做多型性的分子標記，收集族群中的遺傳變異。藉由這些遺傳多型性的資料估計各種族群遺傳參數與檢測族群結構。本研究發現紅星杜鵑相對於玉山杜鵑複合群其他物種，其遺傳歧異度明顯低於台灣杜鵑。另外，依據長期基因交流量與MSVAR的檢測發現玉山杜鵑複合群早期的有效族群數量大，M-ratio分析檢測到玉山杜鵑複合群經歷族群縮小的歷史，以上證據顯示玉山杜鵑複合群經歷族群縮小，由以紅星杜鵑比其他物種更嚴重。玉山杜鵑複合群族群隨距離而升高分化的程度，顯示族群因為縮小事件而降低基因交流的量導致分化，遺傳結構的分析顯示距離相近的族群其遺傳結構相似，以上兩點顯示玉山杜鵑複合群盤據於各山上的族群正在分歧。不同方法檢測到玉山杜鵑複合群天偏離中性演化的基因座，顯示玉山杜鵑複合群族群破碎化之後進行在地適應演化。

關鍵字

杜鵑

並列摘要

Rhododendron pseudochrysanthum species complex constitutes of R. pseudochrysanthum, R. morii, R. rubropunctatum and R. hyperythrum. Species in the R. pseudochrysanthum complex are all endemics to Taiwan and they are morphologically similar. Previous studies revealed that R. rubropunctatum was the origin of this species complex in which Pleistocene range expansion was found and population fragmentation occurred since the last glacial maximum. Aims of this study were to gather information to trace the effect of bottleneck that resulted in reduction of effective population size and genetic structure.
Based on expressed sequenced tag (EST)-derived simple sequence repeats (SSRs) marker system, genotyping data of 27 EST-SSRs were analyzed and population genetic parameters were estimated. Severe bottleneck was found in the R. rubropunctatum populations and high level of genetic divergence in comparison with populations of other species in the R. pseudochrysanthum complex. In addition, high level of genetic divergence is associated with local climatic factors and resulted in local adaptation.

參考文獻

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