並列タイトル等Whole-genome sequence analysis of the evolutionary history of the reef-building coral genus Acropora (Scleractinia, Cnidaria)
授与機関名Okinawa Institute of Science and Technology Graduate University
一般注記A major goal of evolutionary biology is to understand the roles of evolutionary and ecological factors in rapid speciation and diversification. Introgression and ancient large-scale/whole genome duplication (paleopolyploidy) have been hypothesized to promote on rapid speciation leading to diversification. In addition, diversification can be promoted by ‘ecological opportunity’ created by extinction of competitors or the colonization of a new area. Reef-building corals are the foundation of diverse tropical ecosystems, but are currently under threat due to the sensitivity of corals to climate change and anthropogenic factors. Acropora (Anthozoa: Acroporidae) is one of the most diverse genera of reef-building corals, including more than 150 species, and based on the fossil record has dominated IndoPacific reefs in past 3 Million Years, yet the evolutionary and ecological factors associated with its diversification and the rise to dominance are unclear. Understanding the evolutionary history of this group during its rise to dominance may help understanding their current and future responses to global change. In this dissertation, I used genomic data of Acropora generated by Dr. Chuya Shinzato to investigate its evolutionary history and illuminate the roles of introgression, largescale genome duplication, and ecological opportunity in its diversification and the rise to dominance. In the first chapter, I reviewed recent studies of Acropora. In the second chapter, I examined the roles of introgression in Acropora. I found that a major introgression event and widespread gene flow occurred in five Acropora species, and that introgression genes evolved faster than others. In the third chapter, I examined the roles of climate change in the rise to dominance of Acropora. I found that Acropora lineages had an experience of population expansion after a climatedriven mass extinction event in the Plio-Pleistocene, suggesting ecological opportunity facilitated the rise to dominance of Acropora. In the fourth chapter, I examined evidence for large-scale genome duplication and its consequences in Acropora. I found a large-scale genome duplication event likely occurred in Acropora and duplicated genes play important roles in the diversification of Acropora. Finally, in the fifth chapter, I discussed limitations and future directions arising from this dissertation. Collectively, this dissertation suggests that introgression, climate change, and large-scale genome duplication play important roles in the evolutionary history of Acropora.
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受理日（W3CDTF）2019-06-03T12:31:31+09:00
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