| Summary: | 博士 === 國立臺灣師範大學 === 生命科學研究所 === 98 === In this dissertation, I focused on the systematics, phylogeny and the process of species differentiation of Asarum section Heterotropa in Taiwan.
In the systematic study, I performed morphometric analyses to resolve the taxonomic problems in the A. macranthum complex. The results support that the complex should be treated as three taxa, A. macranthum, A. macranthum var. ampulliflorum and A. taitonense. The stigma and style morphologies, the patterns on the inner wall of perianth,
and the shape of the perianth-tube are the most important characters to identify the Taiwanese Heterotropa. Based on these characters, we divided all Taiwanese Heterotropa into three groups. However, this grouping is inconsistent with the grouping of the nrDNA ITS phylogenetic analysis. In addition, according to ITS phylogenetic tree, the closest relations of the Heterotropa species in Taiwan are with Ryukyu Islands and south Kyusyu.
Phylogeographical study on the Taiwan clade showed high
differentiation in the genetic structure among the populations in the Taiwan clade. The result may be due to the specific growth patterns, pollination mechanism and seed dispersal systems of this group. According to the results of nested clade phylogenetic analysis, time of the
most ancestor estimation and Bayesian skyline plot, I inferred the demographical history of the Taiwan clade should be resulted from populations invading a new environment and the influence of extremely VI dry and cold climate in Last Glacial Maximum.
In conclusion, I confirmed that there are twelve Heterotropa taxa in Taiwan, including 11 species and one variety, and ten of twelve are endemic. The ancestor of Heterotropa species in Taiwan originated from the area between Southeast China and Japan based on the phylogenetic
inference. In addition to the influence of Pleistocene climatic fluctuations, the main factors that affected the species differentiation of Taiwanese Heterotropa may be correlated with its biological characteristics, such as
the growth patterns, pollination mechanism and seed dispersal systems in this group.
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