EAPSI: Evolution and Biogeography of an East Asian-North American Distribution in Sedges, a Hyper-Diverse Group of Flowering Plants

莎草属（苔草属）是五大显花植物属之一，也是温带最具多样性的植物属。莎草，估计有2100个物种，是一个理想的群体，用于研究生物多样性和进化的更广泛的模式，由于1）属中的高物种多样性，2）由微生境专业化驱动的物种形成，和3）物理扩散的能力有限。在该属中，有一个约60个物种的分支，分布在北美和欧亚大陆，在美国东部和日本有两个生物多样性中心。该项目将利用分子系统学和地理学方法相结合，重建这些莎草的进化关系，并模拟其地理范围随时间的变化。该奖项将允许研究人员前往日本对东亚莎草进行采样，包括分布范围很窄的日本特有种。实验室工作将产生DNA序列，与之前由北美莎草主要研究者产生的数据相结合。这是与冈山理科大学的植物系统学家和莎草专家星野拓二博士合作的研究项目。在日本的研究期间，将从收集的二氧化硅干燥的叶片样本中提取DNA。将通过PCR靶向并扩增6个DNA序列区域。将使用Sequencher编辑生成的DNA序列，然后使用程序MUSCLE手动比对。BEAST是一个用于系统发育分析的贝叶斯程序，将被用来重建一个组合的特征系统发育，并通过用化石数据校准节点年龄来进行分歧定年。这项研究将检验这一假设，即该分支曾经广泛分布在北方半球的一片连续森林中，而现在的多样性模式是由于北美东部和日本最近的物种辐射。这项工作将调查的作用，Beringia发挥在塑造当今植物群的多样性模式，并检查长期的范围转移扩散有限的植物群由于气候和环境的变化。东亚和太平洋夏季研究所计划下的这个奖项支持美国研究生的夏季研究，由NSF和日本科学促进会共同资助。

Sedges (genus: Carex) are one of the five largest genera of flowering plants, and the most diverse plant genus in the temperate zone. Sedges, with an estimated 2100 species, are an ideal group for examining questions about broader patterns of biodiversity and evolution due to 1) high species diversity in the genus, 2) speciation driven by microhabitat specialization, and 3) restricted ability for physical dispersal. Within this genus, a clade of about 60 species in sections Laxiflorae, Paniceae, Limosae, and Bicolores are distributed widely across North America and Eurasia, with two centers of biodiversity in the eastern United States and Japan. The project will utilize a combination of molecular systematics and biogeographic methods to reconstruct the evolutionary relationships of these sedges and model their geographic range shifts through time. The award will allow the researcher to travel to Japan to sample East Asian sedges, including narrowly distributed Japanese endemics. Laboratory work will produce DNA sequences that integrate with data previously generated by the principal investigator for North American sedges. This is a collaborative research project with Dr. Takuji Hoshino, a plant systematist and sedge expert at the Okayama University of Science. During the research in Japan, DNA will be extracted from the collected silica-dried leaf samples. Six DNA sequence regions will be targeted and amplified by PCR. The generated DNA sequences will be edited with Sequencher, then aligned manually and with the program MUSCLE. BEAST, a Bayesian program for phylogenetic analyses, will be used to reconstruct a combined character phylogeny and perform divergence dating by calibrating node ages with fossil data. The research will test the hypothesis that the clade was once widespread throughout a continuous forest in the Northern Hemisphere, and that the present-day patterns of diversity are due to recent species radiations in both eastern North America and Japan. This work will investigate role that Beringia played in shaping patterns of diversity in the present-day flora, and examine long-term range shifts in dispersal-limited flora due to changes in climate and environment. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science.