台灣產毛茛科鐵線蓮屬(Clematis L.)植物分子親緣關係之探討

Abstract

The genus Clematis L. (Ranunculaceae) is widely distributed all over the world with about 300 species. They were divided into seven subgenera mainly according to morphologies as well as anatomical and palynological evidence. There are 21 taxa of Clematis recognized in Taiwan, which belong to four subgenera, i.e. Campanella, Clematis, Flammula and Tubulosa. In this thesis I used the sequences of nuclear ribosomal ITS (nrITS) region and chloroplast trnK/matK to infer the phylogenetic relationships among Taiwanese Clematis. The sequences were analyzed separately and in combination, and compared with the phylogeny based on morphological characters. All of the 20 taxa of Clematis in Taiwan were obtained and the sequences were determined successfully, excluding the uncertain species C. uncinata var. okinawensis. The final data set also includes 32 taxa of Clematis in Japan (sequences from GneBank, with three taxa also found in Taiwan). Using Anemone flaccida as outgroup, three separate analysis were employed: maximum parsimony, neighbor joining and Bayesian inference. Partition homogeneity test for trnK/matK and nrITS indicated that these two data sets contain significantly different signals. Nonetheless, since the major grouping between these two data sets are similar, we performed a combined data analysis for inferring phylogeny to access total evidence in that manner. Based on the phylogeny, subgenus Flammula is the basal clade, while the relationships of all the other subgenera are unresolved. Subgenus Campenalla and Clematis are shown to be paraphyletic groups. The phylogenies based on DNA sequences and morphology show certain level of incongruence, suggesting a re-examination at intra-genic level for the genus Clematis. C. grata, the most divergent taxa in terms of its morphology, showed certain degree of populational differentiation based on trnK/matK and nrITS sequence analysis. The populations close to ocean show several nucleotide differences from the inland populations, however a thorough survey is needed to draw unambiguous conclusion.