2011-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/702625摘要：台灣紅豆杉(Taxus sumatrana)是瀕臨絕種的裸子植物，棲地流失和人類濫採嚴重的影響到其生存。殘存的族群零星分佈於海拔1500到2800公尺的山區鬱閉森林內。雖然初步的分子族群遺傳資料顯示其與菲律賓產南洋紅豆杉親緣最相近，但形態上台灣紅豆杉與東亞其他紅豆杉難以區隔，所以其分類地位及與亞洲產的紅豆杉之間的親緣演化關係尚待釐清，而這也困擾著保育政策的執行。為了釐清台灣紅豆杉和鄰近地區種群(華東和菲律賓)之間的親緣關係，我們計畫以葉部形態分析比較這些種群的差異，並且比對核醣體ITS 及葉綠體的trnL-F區域序列，來推測這些種群之間的親緣譜系及分類界定。由於種的界線不明，所以實驗設計上採樣的單位為族群，透過採集這些地區的族群，進行分子及形態分析以界定這些紅豆杉的分佈範圍。由於台灣紅豆杉族群個體數量稀少，加上孑遺族群的分布零星不連續，族群間遺傳分化程度和整體的遺傳多樣性必須深入瞭解，故我們同時採用微衛星體標記來分析族群的遺傳結構和台灣各族群間基因流動的程度。經由調查族群間遺傳多樣性的程度和分佈，我們方得以了解族群破碎化對這些尚存族群可能造成的影響以及衝擊的程度。尤其紅豆杉是雌雄異株，基因交流受限對其族群存活相當不樂觀，甚至導致近親交配併發嚴重的近交衰敗。我們的研究結果將提供台灣紅豆杉和華東及菲律賓種群間更清楚的親緣關係，並確立其分類地位，並提供台灣紅豆杉的保育建議。<br> Abstract: The Taiwanese Yew (Taxus sumatrana) is an endangered gymnosperm species in Taiwan, greatly suffering from habit loss and overexploitation. The extant extremely small populations are scattered in forests in shady mountain valleys at altitudes between 1500 and 2800m. The taxonomic status of T. sumatrana and its evolutionary relationships with other East Asian Taxus species remain unresolved, though they appear to constitute a genetic lineage together with populations from the Philippines. Morphologically, though they are difficult to define and distinguish from other Asian Taxus taxa based on current knowledge. This complicates conservation efforts. To clarify relationship of Taiwanese Yew from other Taxus species in adjacent regions including E China and the Philippines, we plan to compare leaf characters and sequence nuclear ribosomal DNA ITS and chloroplast trnL-F regions to infer their possible phylogeographic relationship and species delimitation. Our morphological and molecular analyses will be conducted with samples at the population level among these geographic regions to delineate distribution boundaries. Due to the small number of plants in Taiwan it is paramount to determine the levels of genetic diversity and connectivity left in across the scattered populations, for which we will employ microsatellite markers to analyze the genetic population structure and estimate the levels of gene flow between populations. Knowledge of the level and distribution of genetic diversity in these extant populations will allow us to explore whether population fragmentation has greatly affected the plants. Reduced gene flow and increased consanguineus (between closely related individuals of this dioecious plant) mating, can lead to deleterious inbreeding effects. Our study shall provide a taxonomic concept, and provide baseline data for the establishment of an effective conservation program for the Taiwanese Yew.冰河避難所種子傳播遺傳分化分子時鐘refugiaseed dispersalgenetic differentiationmolecular clock