合囊蕨科5种中国特有珍稀濒危莲座蕨保护生物学研究

Large primitive eusporangiate ferns are megadiverse in China, however, most species are endangered. The proposed project aims to study the conservation biology of five rare and endangered endemic species of Angiopteris (Marattiaceae), namely, A. bipinnata, A. chingii, A. henryi, A. sparsisora, and A. subrotundata, in China, by integrating approaches in population biology, ecology, genetics, and molecular biology. The objectives of this proposal include : (1) studying the biological characteristics of each species, especially characteristics of spores and sporangiate development, and characteristics of reproductive biology such as the gametophyte forms, in order to explore of the reasons of the endangered status; (2) using ISSR and AFLP molecular markers to identify genetic diversity among the different populations; (3) investigating in the field the ecology of the wild populations in order to find similar wild habitats for ex-situ conservation; and (4) gathering in the wild well-developed sporangia in wild popualtions and proceeding spore germination experiment to observe the characteristic of gametophyte development, and to understand population regeneration ability; and (5)testing for vegetative propagation, to find out effective save measures for the protection and rehabililation of critical endangered species, such as A. sparsisora. The results of this project will provide not only scientific basis for the conservation of the five rare and endangered endemic species of Angiopteris, but also help policy-makers design proper measures to conserve other eusporangiate ferns in general.

中国是原始、大型厚囊蕨类植物特别丰富的国家，但多数种类处于濒危状态。本研究拟以5种中国特有珍稀濒危莲座蕨为对象，从居群生物学、生态学、遗传学、分子生物学等多个角度开展保护生物学研究，目的在于：①探明莲座蕨孢子、孢子囊发育特征，以及配子体形成机制等繁殖生物学特性是否是其濒危的关键因素，并提出相应保护拯救措施；②利用ISSR及AFLP分子标记分析手段，查明5种莲座蕨的遗传分化和变异程度，以及居群空间遗传结构特征，以便明确保护重点和引种策略；③通过野外生态学调查，查明野外相似生境迁地保护中的关键生态因子，进而探索出行之有效的迁地引种保护措施；④通过收集各个种发育良好的孢子进行孢子萌发、配子体发育特征观察试验，以查明各个种自我更新能力；⑤开展无性繁殖试验，为法斗莲座蕨等极濒危种寻找有效的拯救措施。研究结果将为5种莲座蕨保护工作提供科学依据，也将有助于深入认识厚囊蕨类植物中存在的一些基础生物学问题。

本项目基于前期的工作积累，对我国特有的合囊蕨科二回莲座蕨、秦氏莲座蕨、阔羽莲座蕨、法斗莲座蕨、圆基莲座蕨5种珍稀濒危莲座蕨开展了保护生物学研究，重点从居群分布格局、居群繁殖生物学、居群遗传多样性、濒危原因进行了深入研究，结果表明：二回莲座蕨和秦氏莲座蕨居群属稳定型，但居群数量较少，容易受环境胁迫和人为干扰；法斗莲座蕨植株数极少，居群结构极不稳定，已濒临灭绝；圆基莲座蕨居群结构稳定，阔羽莲座蕨居群结构相对稳定，但受人为干扰较大。从50条随机引物中筛选出能扩增出清晰、稳定条带的10条ISSR引物、8条AFLP引物，对6种莲座蕨居群基因组进行DNA 扩增，共扩增出162条条带，多态性条带比率为100%，Nei基因多样性指数(H)为0.3000，Shannon 多样性指数(I)为0.4569，遗传分化指数(Gst)为0.1557，居群遗传一致度和遗传距离分别为：0.8642～0.9704 和0.0289～0.1191。结果表明，圆基莲座蕨居群Nei遗传多样性最高，法斗莲座蕨Nei遗传多样性最低。导致5种莲座蕨（特别是法斗莲座蕨和二回莲座蕨）濒危的最主要原因是人类活动的影响，5种莲座蕨均需采取原位保护和迁地保护加以保护，特别是法斗莲座蕨和二回莲座蕨亟需通过人工抚育来恢复居群数量，以实现抢救性保护。