我国重要经济红藻紫菜物种系统分类学研究

Porphyra sensu lato (Bangiales, Rhodophyta) is one of the most important marine biological resources in China with critical economic, ecological and cultural value. The species of Porphyra in China are diverse and traditional taxonomy based on morphology has contributed considerably to the species identification. However, when the global taxonomy of Porphyra was subject to a major revision based on molecular analyses, the taxonomy of this group lagged behind in China. Taxonomic changes have been made based on molecular data without the participation of Chinese phycologists or analysis of Chinese Porphyra samples. Given the diversity of Porphyra species in China coupled with the biogeographically strategic importance of the Chinese coast in the North Pacific, the lack of a molecular taxonomy of Porphyra in China therefore represents a major knowledge gap in the global understanding of this group of organisms. Based on our previous work, we have found considerable cryptic diversity in Chinese Porphyra, evidence of undescribed genera in the revised taxonomic system and the difficulty of identifying unknown taxa because of the lack of DNA barcodes from holotype materials. Furthermore, the considerable genetic diversity within Porphyra sensu lato is not reflected in the morphology. The aim of this project is to determine the biodiversity and generic relationship of Porphyra in China based on molecular taxonomy, to establish a reference collection or holotype for Chinese existing or new species, to review the morphological characters in the light of molecular result in order to assist with identification in the lag and field. To achieve these aims need an extensive collection. We already have a large herbaria collection (680 specimens) and in addition we will continue to collect from unsampled regions. This will not only fill a knowledge gap, but also provide valuable information to taxonomy, ecology, resource conservation and aquaculture studies.

紫菜是我国重要的海洋生物资源之一，具有重要的经济、生态和文化价值。我国紫菜物种丰富，传统分类为紫菜物种鉴定做出了不可磨灭的贡献。目前基于DNA条形码，紫菜分类体系正不断修订，然而这些修订既没有我国藻类学者参与，也没有分析我国紫菜样品。我国紫菜分类研究成为世界紫菜分类研究“拼图”中缺失的一块。在对我国紫菜分类研究中，我们发现我国紫菜有隐含的多样性，许多物种在新分类体系中归属不明，大部分特有物种没有模式标本的DNA条形码因此难以对新发现的未知分类单元进行鉴定，以及传统分类与分子分类冲突等问题。针对这些问题，本项目以已有的680余株紫菜标本为基础，对未采集样品区采样、制作标本，以大标本量为基础，用DNA条形码分析我国紫菜物种多样性和在新分类体系中的归属，结合形态确定未知物种身份，设立我国紫菜已知物种的新标本和新物种的模式标本，以DNA条形码与形态一一对应为基础，探索传统与分子分类的契合点。

紫菜因其形态简单、多变，单单依靠形态学对其物种系统分类是众所周知的难题。随着分子生物学手段的介入，紫菜分类体系发生了重大修订，然而我国利用分子生物学手段在紫菜物种系统分类学方面的研究尚属空白。我国究竟有多少紫菜物种？这些紫菜物种在新的分类体系中处于什么样的位置？我国的紫菜系统分类研究会对该领域研究带来什么样的启发？为解决这些问题，在本国家自然科学基金青年基金的资助下，课题组赴我国沿海北起辽宁、南至海南120余处地点进行采样，采集、制作紫菜标本超过600株，对不同物种进行形态观察，同时获得与标本、形态一一对应的DNA条形码，包括rbcL、18S和COI-5P基因序列，超过1000条，已发表并提交至NCBI获得序列号的DNA条形码563条。研究发现我国沿海约有紫菜物种15个，这与此前经典分类报道的约20余种不同。除已报道的6个物种外，还在我国发现了4个新纪录种，鉴定描述紫菜新种1个。基本确定了所研究的每种紫菜在我国沿海的分布范围，确定了我国紫菜所有物种在新分类体系中的归属，提出了“西北太平洋(包括我国沿海)是紫菜现代分布的起源中心”这一假说，提高了我国藻类分类学的地位和重要性。根据现有数据，对现行紫菜分类体系进行了修订，提出4个新属，使我国紫菜系统发育和分类学研究走在国际前列。课题组共发表SCI论文4篇。研究成果获得“中国藻类学研究优秀论文三等奖”1项，南通市“自然科学优秀学术文论一等奖”1项。