瑞香属和荛花属（瑞香科）的分类与系统学研究

The genera Daphne L. and Wikstroemia Endl. belong to the family Thymelaeaceae with species widely used in horticulture, paper-making and medicine. The two genera included about 160 species worldwide in total, with 100 species distributing in China. South-western China is the important distribution center of both genera. The phylogenetic relationship between Daphne and Wikstroemia have been controversial for a long time and the infrageneric classification within each genus is still unclear. In this project, morphological characters，molecular sequences of single or low copy nuclear genes and chloroplast DNA sequences will be used to reconstruct the phylogenetic relationship among Daphne, Wikstroemia and other related genera based on comprehensive material collection. Consequently, the taxonomic status, generic limit as well the phylogenetic relationship of Daphne and Wikstroemia will be clarified. The intrageneric taxonomic structure within Daphne and Wikstroemia will be tested and revised. Meanwhile, the taxonomic status and species boundaries of some sibling species, morphologically similar species and several difficult to identify species will be confirmed. Furthermore, character evolution based on combination of morphological variation and molecular data will be traced to provide evidence for comprehensive and reasonable taxonomic revision of Daphne and Wikstroemia.

瑞香属(Daphne L.)和荛花属(Wikstroemia Endl.)隶属于瑞香科(Thymelaeaceae)，在园林、造纸和药用方面都有广泛的应用。全世界共有瑞香属和荛花属植物160余种，中国有100余种。中国西南是两类群的重要分布中心。瑞香属和荛花属间的系统关系一直存在争议，两属植物内部的系统发育关系仍不清楚。本项目旨在以瑞香属和荛花属为主要研究对象，全面采集两属的植物种类，结合形态性状和基于叶绿体DNA与单拷贝或低拷贝的核基因序列的分子证据，对瑞香属、荛花属及邻近属进行系统发育重建。本研究将明确两分类群的系统分类地位、分类界限及相互间的亲缘关系，完成对已有属下分类等级的检验与修正，厘清近缘种、近似种及部分分类困难类群的分类地位。通过结合形态变异与分子证据探讨瑞香属与荛花属植物系统发育过程中的性状特征演化，进而为全面、合理地对瑞香属、荛花属进行分类修订提供重要的科学证据。

瑞香属和荛花属许多种类韧皮纤维发达，可供造高级纸和人造棉原料，有的种类引种庭园栽培，是较好的花卉观赏植物，部分种类可作药用。瑞香属和荛花属间的系统关系一直存在争议，两属植物内部的系统发育关系仍不清楚。项目通过完成瑞香属、荛花属的分子系统学、形态及微形态方面的研究，明确了1、瑞香属是一个多系类群，荛花属是一个并系类群，瑞香属和荛花属为独立的属、应保留两属各自独立的分类地位；2、确认了荛花属与狼毒属的亲缘关系，建议两属归并；4、提出瑞香属和荛花属在传统形态分类过程中出现性状交叉的一个原因是由于物种属放置不正确；5、明确了芫花、橙黄瑞香、华瑞香、丝毛瑞香、狭瓣瑞香、穗花瑞香等类群分类上应属于荛花属物种。通过本研究，为后续全面、合理地对瑞香属、荛花属乃至中国瑞香科植物进行分类修订提供了科学的证据，也为更好地开展中国瑞香科植物资源利用提供了重要的基础资料。