喜岩菫菜複合群之親緣關係與分類研究

Abstract

喜岩菫菜複合群 (Viola adenothrix complex) 包含兩個在形態上非常相似的類型，即喜岩堇菜 (Viola adenothrix var. adenothrix) 與雪山菫菜 (V. adenothrix var. tsugitakaensis )，兩者皆為台灣特有類群，前者主要分布於中海拔 (1000~2500 m)，而後者主要分布於高海拔(2500~3900 m)。本研究利用形質分析與分子標記探討此複合群的親緣關係與分類問題。 利用87個樣本進行形質分析，共測量19個形態特徵。根據變異數分析(ANOVA)結果顯示在兩類群間有6個特徵 (基瓣寬、萼片寬、花軸長、側瓣鬚毛數、葉厚、葉長/葉寬) 具顯著差異；綜合區別分析(discriminate analysis) 與歸群分析 (cluster analysis) 的結果顯示兩類群在形態上已有區分為二的趨勢，但仍存有不少中間型個體。 分子分析共使用226個樣本，合併葉綠體trnV-trnM與trnG-trnS兩片段進行分析，共獲得21個變異位點，可組成21個單套型。根據AMOVA的結果顯示在喜岩菫菜與雪山菫菜間僅有2.58%的變異(P=0.17)，且兩類群共有單套型佔全部樣本比例達73.45%，顯示兩者分化程度低。推測造成形態與分子資料呈現如此趨勢，可能是此二者為近代分化，現仍處於譜系分化不完全(incomplete lineage sorting)的階段。 Tajima’s D test與mismatch distribution的結果及基因樹呈現星狀結構，推測喜岩菫菜複合群近期經歷了族群擴張。 綜合形質與分子資料分析的結果，本研究支持台灣植物誌第二版（Wang and Huang, 1993）將雪山菫菜視為喜岩菫菜的一個變種之分類處理。Viola adenothrix complex contains two morphologically similar forms which were usually treated as two varieties, namely V. adenothrix var. adenothrix and V. adenothrix var. tsugitakaensis. Both of them are endemic in Taiwan and are distributed in medium (1000~2500m, V. adenothrix var. adenothrix ) and high elevation (2500-3900 m, V. adenothrix var. tsugitakaensis. ) respectively. The present study investigates the phylogenetic and taxonomic relationship of them by using morphological and molecular data. In morphometric analysis, a total of 87 samples and 19 characters were measured. The results of ANOVA show that six (width of basal petal, width of sepal, length of floral axis, number of beard in the lateral sepal, thickness of leaves, and ratio of length to width of the leaves) out of 19 measured characters are significantly different between the two taxa. Discriminate analysis and cluster analysis also show that they trend to separate into two groups in spite of some morphologically intermediate individuals. Two chloroplast DNA regions (trnV-trnM and trnG-trnS) were used in molecular analysis. 21 variable sites and 21 haplotypes were obtained from a total of 226 samples. Based on the AMOVA result, only 2.58% variation (P=0.17) between V. adenothrix var. adenothrix and V. adenothrix var. tsugitakaensis. Based on minimum spaning network, the samples shared the haplotypes of two taxa are up to 73.45% of all. Both the patterns from morphological and molecular data suggest that the two taxa might differentiated recently and are in the stage of incomplete lineage sorting. Beside, the result of minimum spanning network show that the haplotype of V. adenothrix var. tsugitakaensis was derivated from V. adenothrix. Based on Tajima’s D test, dismatch distribution and the star-like phylogeny result, the species complex might undergo population expansion recently. In conclusion, the present study support to Wang’s treatment (1988) in which V. adenothrix var. tsugitakaensis was treated as a variety of V. adenothrix.