Korean Entomological Institute, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea.
Molecular Ecology and Evolution Laboratory, Department of Biological Science, Sangji University, Wonju, Korea.
PLoS One. 2019 Jul 23;14(7):e0219958. doi: 10.1371/journal.pone.0219958. eCollection 2019.
Species diversity in the genus Ulva remains understudied worldwide. Using molecular analyses we investigated the species composition, diversity, distribution, and relative frequencies of the genus Ulva along the entire coast of Jeju Island, off the southern tip of Korea. Species identification was performed for 215 samples collected from 23 sites, based on comprehensive phylogenetic and model-based species delimitation analyses using the sequences of two molecular markers, chloroplast elongation factor Tu (tufA) and nuclear rDNA internal transcribed spacer (ITS). We identified 193 specimens as nine Ulva species, 14 specimens as Blidingia spp., and eight samples undetermined, based on the combined analysis of tufA and ITS phylogenies. Two model-based approaches generally supported nine groups of Ulva species. Previously documented species complex, such as U. ohnoi-U. spinulosa and U. procera-U. linza showed discordant relationships between the two phylogenies. The occurrence of U. torta on Jeju Island was first observed, despite its existence on the mainland previously reported. Ulva australis [16 of 23 sites; 34.4% (relative frequency)], U. ohnoi (16; 21.9%), and U. procera (11; 14%) were found to be the predominant species. Our study highlights that molecular analysis is critical for species delimitation in the genus Ulva and provides fundamental information for an understanding of green-tide assemblages on the "biological hotspot" coastal ecosystem, Jeju Island in Korea. This study will also help to monitor and manage local green tides at the areas that are currently encountering rapid climate changes.
全世界对石莼属的物种多样性研究仍然不足。本研究采用分子分析方法，调查了韩国南端济州岛沿海地区石莼属的物种组成、多样性、分布及相对频率。基于两个分子标记（叶绿体延伸因子 Tu（tufA）和核 rDNA 内转录间隔区（ITS））的综合系统发育和基于模型的物种界定分析，对 23 个采样点采集的 215 个样本进行了物种鉴定。根据 tufA 和 ITS 系统发育的联合分析，鉴定出 193 个标本为 9 种石莼属，14 个标本为 Blidingia spp.，8 个样本未确定。两种基于模型的方法通常支持 9 组石莼属。先前记录的物种复合体，如 U. ohnoi-U. spinulosa 和 U. procera-U. linza，在两个系统发育树之间表现出不一致的关系。石莼属 U. torta 在济州岛的出现是首次观察到的，尽管此前在大陆地区已有报道。在韩国济州岛发现了 U. australis（23 个采样点中的 16 个；相对频率 34.4%）、U. ohnoi（16 个；21.9%）和 U. procera（11 个；14%）等优势种。本研究表明，分子分析对于石莼属的物种界定至关重要，并为理解韩国济州岛这一“生物热点”沿海生态系统中的绿潮组合提供了基础信息。本研究还将有助于在目前正在经历快速气候变化的地区监测和管理当地的绿潮。
