The origin and evolution of alpine hexaploid Silene in Taiwan

• Main Authors: Fu-Lung Shih, 施福隆
• Other Authors: Jenn-Che Wang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/04043867028603668337

碩士 === 國立臺灣師範大學 === 生命科學研究所 === 100 === Three endemic Silene species distributed on high-altitude mountains in Taiwan re-spectively are S. morrisonmontana var. morrisonmontana, S. morrisonmontana var. glabella and S. formosamotana. Together they were called S. morrisonmontana complex for having similar morphological traits and same haplotypes of some gene regions, and are all hexaploids. According to geographical distribution and morphological characters, their origin species possibly are: (1). The phylogenic-closed tetraploids S. aprica and S. firma which also distributed in Taiwan, (2). The companion species S. hupehensis, S. salicifolia and S. tubiformis of sect. morrisonmontanae. But if S. morrisonmontana complex were formed out of Taiwan or through allopolyploidy, then their source would rather be the other species. In this study, we use three chloroplast (matK, rps16 and psbE to petL intron) and two nuclear (RPD2a and RPD2b ) gene regions as molecular markers. The sequence data were obtained both from materials collected in Taiwan and GenBank. We wished to clarify the origin of S. morrisonmontana complex and estimate the possible temporal and special background of it by the construction of phylogeny tree and phylogeographic analysis. The results showed three species of S. morrisonmontana complex shared same hap-lotypes in all five gene regions, and those were all respectively grouped in high-ly-supported clade. Base on it, S. morrisonmontana complex are estimated to have a single origin, and differentiated into three species recently. Also, the haplotypes of two nuclear gene regions were grouped into two different clades respectively sugessested S. morrisonmontana complex are allopolyploids. Neither S. aprica, S. firma nor S. hupe-hensis, S. salicifolia are the origin species, because their haplotypes of five gene regions were all in the different highly-supported clades with S. morrisonmontana complex. There was no species with lower ploid-level completely fit in the same clade with S. morrisonmontana complex, suggesting that the origin species may be extinct or not in-cluded in this study. Thought S. nangqenensis could possibly be the maternal origin base on the result of rps16 and psbE/petL intron combined sequence, but still unsolved for the lack of nuclear genes and ploidy information. Whether chloroplast or nuclear markers showed that the most closed species of maternal origin were distributeted in the Qinghai-Tibet Plateau, and of paternal origin were in Northeast Asia based on the result of RPD2a region. Infer from this, S. morrisonmontana complex might derive from the hybridization between two geographic-distinct species when they encounter each other. Moreover, S. himalayensis shared with S. morrisonmontana complex the same maternal origin which also could be the paternal origin of S. gonosperma.