小檗科小檗屬之分子親緣關係與歷史生物地理學

Abstract

小檗科亞中的屬 (Berberis L.)，目前界定約有 ，目前界定約有 500多種，是真 雙子葉植物基群中少見的高度多樣化木本類之一。儘管屬在園藝與藥用上有重要的經濟價值，但傳統物種鑑定一直十分困難本論文首次以多變數分析方法以及 General Lineage Concept (GLC) 理論來界 定小檗的物種理論來界 定小檗的物種線，以臺灣產的瓦氏組小檗之訂正做為案例獲得了實際成效。兩百年來儘管小檗屬展現了高物種多樣性以及有趣的地理分布形式，但因為與近緣間、屬內的親緣關 係未被解析，使得分類工作迭有爭議嚴重阻礙了對本屬演 化和生物地理學研究的進展。本論文嘗試以核醣體內轉錄區間序列 (nrITS) 結 合八個葉綠體 DNA 片段 (accD、ndhF、 rbcL、psbA-trnH、rpl32-trnL、rpoB-trnC、trnS-trnG 和 ycf6-psbM)，合併分析小檗屬與十大功勞的子親緣關 ，合併分析小檗屬與十大功勞的子親緣關 係。結果顯示小檗 屬是一個高度支持的單系群，但十大功勞卻由克萊爾(B. claireae Moran)、典型十大功勞 和沙漠、典型十大功勞 和沙漠(M. sect. Horridae C.K.Schneid.) 等三個在形態、生與地理分布均獨特的支序組成，小檗屬呈 現駢系關係。在進一步考量此四個分類群之起源年代與小檗科內其他成員相近或更古老，本論文進一步提出將克萊爾小檗、沙漠十大功勞另立為兩個新屬分別為摩倫木屬(Moranothamnus C.C.Yu & K.F.Chung) 和異小檗屬 (Alloberberis C.C.Yu & K.F.Chung)。這樣的分類處理，不僅合反映了小檗亞科 內木本譜系的演化關係，也維持了過往相領域中對小檗屬認知然而新親緣關係卻也同時挑 戰了過往小檗屬內的分類架構，許多重要組 (section) 和亞組 (subsection) 被發現多為系群。但相對地，新的親緣關係亦 揭露了未知的地理類群，可做為屬內分架構新依據。進一步解這些屬內重要演化譜系的起源和 生物地理學，本論文結合了分子定年、石資訊LAGRANGE 軟體重建了小檗屬內主要支序的可能祖先分布地變遷過程。其 軟體重建了小檗屬內主要支序的可能祖先分布地變遷過程。其 中，小檗屬的熱帶兩側間斷分布可能起源於次獨立、來自北美洲傳播事件，屬內主要支序的起源與演化可能全球新近紀造山運動有關。其中落葉譜系可分為北溫帶與高山 兩大支，各自起源於華中一帶的暖溫山區與喜瑪 拉雅 -橫斷山脈的 高海拔區，而東亞常綠譜系則被推測起源於較乾旱西喜馬拉雅山區。

The shrubby genus Berberis L. harbors more than 450 taxa, representing the most diversified lineage of Berberidaceae, and is widely used in both horticultural and pharmaceutical fields. Despite evolutionary and economic importance, taxonomic standing of Berberis as distinct genus has been the subject of much debate among botanists. This thesis, thus, aims to re-examine the phylogenetic relationships of Berberis using the internal transcribed spacer of nrDNA (nrITS), and three coding regions (accD, ndhF, rbcL) and five non-coding regions (psbA-trnH, rpl32-trnL, rpoB-trnC, trnS-trnG, ycf6-psbM) of the chloroplast genome. The analyses revealed four clades within Berberis s.l., corresponding to Berberis s.str., B. claireae Moran, core Mahonia and M. sect. Horridae, with the latter three forming a paraphyletic grade sister to the simple-leaved Berberis. Because of the morphological and ecological distinctness of these four clades and their deep stem divergences equivalent to other genera of Berberidaceae, a new classification of Berberis s.l. was proposed by applying a strict definition of Berberis (Berberis s.str.), reinstating Mahonia, and proposing the two new genera Alloberberis C.C.Yu &K.F.Chung and Moranothamnus C.C.Yu & K.F.Chung. This revised classification is consistent with the traditional perception of Berberis, maintaining the stable usage of these two household names in both academic and nonacademic communities. Moreover, withing Berberis s.str. the updated phylogeny was basically congruent with the previous classification schemes at higher taxonomic levels. At lower levels, however, most of previous sections and subsections were not validated, showing their potential artificial nature in classification. While the traditional classification was highly challenged here, several geographically highly-structured clades were revealed in both Groups for the first time. A clear phylogenetic split between evergreen and deciduous lineages in Group Septentrionales was also identified. Furthermore, to unravel the complex shared biogeographic history among these lineages, the molecular dating and DEC model based LAGRANGE program was performed across different phylogenetic scale. According to the outcome, the well-known anti-tropical disjunction of Berberisi was explained by at least two independent dispersal events from North America occurring in the Paleogene. For the northern temperate deciduous lineages, most of them were inferred to be originated from East China while the Asian subalpine evergreen lineages arise from the western Himalayas. The active uplift phase of the Himalayas and Chinese Hengduan Mts. during Miocene may give rise to the diversification as well as the strong provisionalism of the Asian alpine deciduous lineages. At last, because of its sheer size, much basic taxonomy is required in Berberis. This thesis hence provided the first example study to delimit the species boundary of Berberis by applying multivariate analysis and General Lineage Concept (GLC), as the case of Taiwanese B. sect. Wallichianae.