碩士 / 國立臺灣大學 / 森林環境暨資源學研究所 / 102 / To investigate the origin of limestone karst biodiversity, this project takes Begonia sect. Coelocentrum as a model system. We incorporate the studies of population genetics and phylogeography of a widely distributed species Begonia luzhaiensis to test the hypothesis of allopatric speciation via isolation-by-distance triggered by extensive karstification. We sampled 10 populations from limestone karst area of Guangxi, China. Using next-generation sequencing (NGS) technique, 16 polymorphic EST-SSR markers was developed from 5,602 contigs, combine with chloroplast DNA sequence trnC-ycf6 as tool of the population genetics study. Significantly high FST suggests strong population differentiation. Based on Bayesian clustering analyses, all populations were restrictively distributed in isolated area. Mantel Tests indicate a significant positive correlation between genetic differentiation and geographic distances, which is also suggested by nested clade analyses of the haplotype network of trnC-ycf6. Historical demography was described by neutrality test, mismatch distribution analysis and Bayesian skyline plot analysis. In the higher level clades, a pattern of range expansion followed by isolation-by-distance was shown, as predicted based on the early developments of karst area. A recent decline of effective population size might have been caused by increased aridity of East Asia at ca. 50,000 years ago during the Pleistocene glacial period. The microevolution patterns of Begonia luzhaiensis suggest that the similar process might have caused allopatric speciation via isolation-by-distance in a larger time scale, and support strongly the importance of extensive karstification in shaping the species diversity on the Sino-Vietnamese limestone karsts. From a conservation prospective, geographically isolated populations on limestone karsts often harbor unique genetic variation that is threaten by rapid habitat destructions and their uniqueness deserves high conservation priority.
| Identifer | oai:union.ndltd.org:TW/102NTU05359034 |
| Date | January 2014 |
| Creators | Han-Yau Huang, 黃瀚嶢 |
| Contributors | Kuo-Fang Chung, 鍾國芳 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 55 |
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