以形態及分子證據探討玉山蠅子草種複合群的分類問題

Abstract

玉山蠅子草種複合群 (Silene morrisonmontana species complex) 包含玉山蠅子草 (Silene morrisonmontana)、禿玉山蠅子草 (S. morrisonmontana var. glabella) 及蓬萊蠅子草 (S. nubigena) 等三個類群，皆為臺灣特有，分布於三千公尺左右的高山地區。本研究以形質分析及分子標記對此一種複合群進行深入研究，形質分析採用12個形態特徵及2個形態比例，對123標本進行形態量化，藉由多變量分析結果推論雪山圈谷之疑問種應歸入蓬萊蠅子草。此種複合群內以植株的被毛程度、萼筒長及雌雄蕊柄長為主要的區分特徵。而分子資料則顯示此種複合群其nrDNA的ITS序列完全一致，兩葉綠體基因片段 (psbA-trnH、rps16) 累積的變異僅10個位點，各類群間基因分化的程度遠少於形態資料所預期，此種複合群應屬形態變異較為快速的物種。因在不同的類群間發現相同的基因型，推論此種複合群應為近年才開始產生基因型分化的物種。Silene morrisonmontana species complex consists of three taxa, namely S. morrisonmontana, S. morrisonmontana var. glabella, and S. nubigena. All of them are endemic in alpine regions above 3000 m in elevation of Taiwan. There were controversies over the taxonomic status of members within this species complex. This study aims to investigate the taxonomy of this species complex using morphometric and molecular informations. Twelve morphological characters and two ratio values were quantified for 123 specimens. By applying multivariate analyses, we found that the questionable form in the Hsuehshan cirque should belong to S. nubigena. The main diagnostic characters for this complex include the degree of hair coverage, length of calyx, and length of androgynophore. Molecular data shows that their ITS (nrDNA) sequences are identical from one another, and only 10 variable sites found in selected chloroplast DNA region (psbA-trnH, rps16). Differentiations among haplotypes are low, and incongruent with their diverse morphology. As similar haplotypes were found in different taxa, we infer that this complex must be still in the process of incomplete lineage sorting, and at initial stage in their differentiation after speciation.