东亚棉藓科植物分子系统及多样性研究

Plagiotheciaceae, one of the most important members of temperate pleurocarpous mosses, is a group with extremely ambiguous definition. The concept of this family has gone a long way from "Plagiotheciaceae sensu lato" to "Plagiotheciaceae sensu strito", and now is fluctuating between "Plagiotheciaceae sensu strito" and a novel "Plagiotheciaceae sensu lato" without a consensus among most bryologists. The information from various molecular markers has become increasingly abundant during the last decade. However, little progress has been achieved about the concept of Plagiotheciaceae, which significantly hampered our comprehensive understanding of the real diversity of this family as well as the whole system of Bryophyta. East Asia, which harbors a large proportion of species in Plagiothecium and other genera of the two "Plagiotheciaceae sensu lato" mentioned above, is a great stage for a phylogenetic study of the family. Based on comprehensive evidences from morphological, anatomical, molecular phylogenetic and molecular genetic studies, the objective of this project is 1) to reconstruct the phylogenetic relationships among the putative genera in Plagiotheciaceae, 2) to redefine the concept of this family, 3) to infer the divergent time of the main lineages and the evolution of main morphological characters in Plagiotheciaceae, 4) to uncover the relationships among species of Plagiothecium and throw light on the relevance among phenotypic variations, genetic differentiation and geographic distance, and 5) to make certain the members of Plagiotheciaceae in East Asia and their distribution.

棉藓科为温带侧蒴藓类的重要成员，也是概念最为模糊的类群之一。该科的概念经历了由广义至狭义，再至狭义与新广义并存的数次变动，但迄今研究者并未就其达成共识。分子标记信息日益丰富的近十年间，棉藓科概念的止步不前严重阻碍了人们对棉藓科植物真实多样性的把握，也严重影响了对藓类植物系统的全局性理解。东亚地区分布有大量棉藓属及其他广义棉藓科物种，是进行棉藓科分子系统研究的良好平台。本项目以东亚地区分布的棉藓科植物为主要研究对象，拟综合运用经典分类学、分子系统学和遗传多样性等研究方法，重新探讨棉藓科的概念，重构其科内属间关系，推测其分化时间和形态特征的演化历程；以棉藓属为核心，推测属下种间关系，探究形态分化、遗传分化和地理距离的关系；并基于所有证据对棉藓科植物在东亚地区的种类及其地理分布情况进行总结分析。

东亚地区是棉藓科分布的中心之一，但对于棉藓科的分类经历了广义－狭义－新广义的多次变动，科属概念模糊。本项研究通过查阅资料，借阅东亚地区已报道具有分布的棉藓科模式标本，赴国外采集或与国内外标本馆交换标本，以及全国范围的野外补点采集，室内形态研究，以及应用现代分子系统学研究手段，选取代表性样本和核基因ITS、gapCp，以及叶绿体rbcL、rps4-trnS、psaB、trnG、trnL-trnF和tRNA-Phe基因片段进行扩增、测序，通过构建分子系统树、单倍型网络分析和物种界定分析手段，全面展开研究。获得的结果主要有：. .1. 分子系统学研究结果支持棉藓科为一个单系类群，明确了新广义棉藓科包括7个属，及新广义棉藓科的概念；.2. 确定东亚地区棉藓科共有36种3变种，其中：棉藓属14种2变种，拟鳞叶藓属8种1变种，拟同叶藓属2种，长灰藓属5种，小鼠尾藓属2种，灰石藓属3种，细柳藓属2种；.3. 提出了3个新组合，4个新地位和10个新异名，发现中国3个新分布（卷边麻锦藓Taxithelium kerianum (Broth.)Broth.，糙柄青藓Brachythecium trachypodium (Funck ex Brid.) Schimp.和短尖拟青藓Sciuro-hypnum ornellanum (Molendo) Ignatov & Huttunen），地区新分布25种；发现越南新记录属10个，新记录种61个。.4. 将牛尾藓属调入棉藓属中，支持将小鼠尾藓属重新归入棉藓科，并提出小鼠尾藓属与灰石藓属和细柳藓属亲缘关系较近；.5. 结合本课题的野外补点采集，进行了滇、桂地区的藓类区系调查和越南地区藓类植物野外调查，并形成名录发表。.6. 收集棉藓科标本近5000份，其他标本万余份。..本项目的研究成果是中国乃至东亚棉藓科研究的最新成果，为该地区棉藓科植物乃至整个苔藓植物研究提供了新资料。本项目研究过程中使用的研究方法将为存在类似问题的其它类群的相关研究提供参考；采集到的万余份标本为后续的相关研究积累了材料。