百合科油點草屬之分子系統學研究：親緣關係、生物地理與臺灣產物種之分類修訂

Abstract

百合科油點草屬是一個侷限分布於東亞的屬，包含約20 種生育地以溫帶為主、少數為亞熱帶的植物。目前油點草屬的研究僅侷限於使用外觀形態及生態觀察、以及支持度不高的分子親緣關係研究，其生物地理起源仍有待進一步研究。臺灣產的油點草屬植物外觀形態自成一格，加上適應於亞熱帶環境的生態習性，特異於本屬分布於臺灣以外的物種。但是從過去多次的學名變動，可看出有部分臺灣產的油點草屬植物似乎不容易從外觀形態確實區別分類群。本文使用5段葉綠體DNA片段 (rps16 intron, trnL-trnF, atpF-atpH, psbM-ycf6, rpl32-trnL spacer) 及細胞核DNA片段ITS，重建油點草屬親緣關係樹，藉此檢測本屬植物的生物地理假說。此外使用2段葉綠體DNA片段 (rps16 intron, trnL-trnF) 及細胞核DNA 的 ITS 序列片段，重建臺灣產油點草屬物種間的基因單型網狀親緣關係圖，藉此檢驗目前的分類假說。根據分子親緣關係進行之生物地理起源分析結果顯示現生油點草屬起源於日本，再擴散至日本以外的區域。臺灣產的物種為單起源，共同祖先可能是來自中國或日本。而臺灣產物種的網狀親緣關係圖結果，並不支持目前臺灣油點草 (T. formosana)、高山油點草 (T. ravenii) 和毛果油點草 (T. lasiocarpa) 分成 3 個種的分類處理，建議應予合併成 1 個種。

The liliaceous Tricyrtis Wall. is an East Asian endemic genus of ca. 20 mainly perennial herbaceous species inhabiting humid temperate environments. Previous biogeographic hypotheses were proposed based on inferences of morphology, ecology, and inadequately executed molecular phylogenetic studies with poor supports. Morphologically, the Taiwanese Tricyrtis are distinct and ecologically exceptional in their mainly subtropical distribution. However, the unsettled taxonomy of Taiwanese Tricyrtis as manifested by a long list of nomenclatural also suggests that further study is needed. This study aims to test the biogeographic hypothesis of the genus and improve the taxonomic treatment of Taiwanese taxa by reconstructing phylogenetic relationship based on DNA sequence data. This study reconstructs phylogenetic relationships of Tricyrtis based on DNA sequences of 5 chloroplast regions (rps16 intron, trnL-trnF, atpF-atpH, psbM-ycf6, rpl32-trnL spacer) and nuclear ribosomal intergenic transcribed spacer (ITS). To test species hypothesis of Taiwanese Tricyrtis, haplotype networks were reconstructed using rps 16 intron and ITS. Biogeographic analyses based on molecular phylogenetic relationships show that current species of Tricyrtis is most likely originated in Japan and subsequently dispersed to Korea, China and other regions. Haplotype networks of both chloroplast and ITS sequences of Taiwanese species reveal non-monophyly of T. formosana, T. lasiocarpa, and T. ravenii, suggesting incomplete speciation of the three taxa. The taxonomic treatment of treating them as three varieties under T. formosana is proposed.