| Summary: | 碩士 === 國立臺灣大學 === 森林環境暨資源學研究所 === 106 === Paper mulberry (Broussonetia papyrifera (L.) L’Hér. ex Vent.), a wind-pollinated dioecious tree native to East Asia, is the cultural necessities of Austronesian-speaking peoples (Austronesians) for making bark cloth (tapa). By studying the geographical relationship among the populations of paper mulberry, the migration path of the Austronesians can be deduced. To increase phylogenetic resolution of previous studies limited by insufficient molecular resolution, we applied restriction-site associated DNA sequencing (RADSeq) collected using next-generation sequencing technology, obtaining 6,322 SNPs from 137 individuals for phylogenetic analysis by Stacks. The outcome reaffirmed that the Pacific paper mulberries were all derived from southeastern Taiwan, and the genetic differences among the Pacific paper mulberry were rare, conforming asexual propagation of the Pacific paper mulberry for tapa making and reaffirming the “out of Taiwan” hypothesis of Austronesian expansion and migration. Tough the genetic differences were rare, we still succeeded in finding the propagation path of paper mulberry in remote Oceania. The previous study, which using the chloroplast marker, showed the strong phylogeographic structure in Taiwan. On the contrary, the lack of phylogeographic structure in Taiwan revealed by RADSeq, which represents the biparental-inherited nuclear genome, suggests high gene flow mediate by efficient pollen dispersal. Nevertheless, Taiwan Strait remains an effective dispersal barrier for pollen dispersal between mainland China and Taiwan. Our RADSeq data also confirm the tight relationship between populations of Ryukyu Islands and eastern Taiwan. However, substantial genetic differentiation is present between the two populations, suggesting a long-term isolation and that the Ryukyus populations were likely established via land bridge during the twice ice age.
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