生物多样性 ›› 2021, Vol. 29 ›› Issue (12): 1607-1619.DOI: 10.17520/biods.2021273

• 研究报告:植物多样性 • 上一篇    下一篇

中国薄叶卷柏复合群的物种划分

张梦华1,2, 张宪春1,*()   

  1. 1.中国科学院植物研究所系统与进化植物学国家重点实验室, 北京 100093
    2.中国科学院大学, 北京 100049
  • 收稿日期:2021-07-09 接受日期:2021-11-03 出版日期:2021-12-20 发布日期:2021-12-16
  • 通讯作者: 张宪春
  • 作者简介:*E-mail: zhangxc@ibcas.ac.cn
  • 基金资助:
    国家植物标本资源库项目(E0117G1001)

Species delimitation of the Selaginella delicatula group in China

Menghua Zhang1,2, Xianchun Zhang1,*()   

  1. 1 State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093
    2 University of Chinese Academy of Sciences, Beijing 100049
  • Received:2021-07-09 Accepted:2021-11-03 Online:2021-12-20 Published:2021-12-16
  • Contact: Xianchun Zhang

摘要:

卷柏属(Selaginella)是石松类植物中最大的属, 也是分类难度较大的类群之一。该属的物种划分主要基于形态特征, 但许多近缘种在形态上很难区分。近年来, 已有大量分子证据被用于各植物类群的分类学研究, 但目前未发现一套适合卷柏属物种鉴定的分子标记。薄叶卷柏复合群(S. delicatula group)是卷柏属下鉴定较为困难的类群, 包括了薄叶卷柏(S. delicatula)、黑顶卷柏(S. picta)和瓦氏卷柏(S. wallichii) 3个物种, 主要分布于亚洲的热带和亚热带地区。为了探讨薄叶卷柏复合群内物种的亲缘关系和评估不同分子标记在卷柏属分类学研究中的应用价值, 本研究对该复合群物种进行广泛取样, 共收集到73个个体, 并选取3个叶绿体基因(rbcL, psbAatpI)和2个核基因(26S nrDNA和pgiC)片段进行系统树的构建及叶绿体单倍型分析。研究发现, 基于叶绿体和核基因构建的系统发生关系存在冲突: 叶绿体基因树上薄叶卷柏个体分为两个分支(A和B), 薄叶卷柏B分支与薄叶卷柏A-S. picta分支呈姐妹关系, 并且rbcL单倍型分析结果也表明薄叶卷柏A和B两个分支存在明显分化; 而核基因结果则支持该复合群3个物种各自的单系性, 其中, S. delicatula分支与S. picta分支为姐妹群, S. wallichiiS. delicatula-S. picta分支为姐妹关系。在对复合群分布区大量标本的观察以及野外群体调查的基础上, 评估了植株茎和枝的分枝方式、孢子叶、营养叶(侧叶、中叶和腋叶)和孢子表面纹饰等形态性状的分类学价值。结果表明, 薄叶卷柏A和B分支的样本仅在植株分枝方式和大孢子表面纹饰上存在差异, 但无法依靠小孢子表面纹饰、孢子叶穗和营养叶形态等特征进行区分。基于现有证据, 薄叶卷柏复合群至少可划分为薄叶卷柏、黑顶卷柏和瓦氏卷柏3种, 但彻底澄清该复合群的物种划分还需要获取模式标本产地的材料和细胞学证据。最后, 建议在未来卷柏属的分类学研究集中于该属分类复杂的复合群, 结合使用形态学、细胞学、分子生物学(同时使用核基因和叶绿体分子标记)及地理分布等整合证据来进行物种划分。

关键词: 26S nrDNA, pgiC, 叶绿体分子标记, 石松类植物, 薄叶卷柏复合群

Abstract

Aims: Species delimitation of Selaginella remains largely based on morphological characters, however, many closely related species are morphologically indistinguishable from each other. This study aims to (1) explore phylogenetic relationships within the S. delicatula group; and (2) evaluate the utility of nuclear and chloroplast DNA markers for the classification of Selaginella.
Methods: A total of 73 individuals were sampled, covering the geographical distribution and morphological variation of this group. We sequenced three chloroplast markers (rbcL, psbA, and atpI) and two nuclear markers (26S nrDNA and pgiC) to infer the phylogenetic relationships and haplotype network.
Results: We detected incongruence within S. delicatula-S. picta clade between chloroplast and nuclear phylogenies. The chloroplast dataset indicated S. delicatula is not monophyletic, with S. delicatula B sister to S. delicatula A-S. picta. In contrast, nuclear dataset discovered the monophyly of all three species, with S. delicatula sister to S. picta and S. wallichii sister to the S. delicatula-S. picta clade. Morphological characters, including main stem and branches, sporophylls, sterile leaves (ventral, dorsal, and axillary leaves) and spores were carefully observed and assessed. Morphological comparisons indicated that the samples of S. delicatula A and B clades are only distinct in branch patterns and the micromorphology of megaspores surface, not differential in morphology of leaves, strobili and microspores.
Conclusion: As a result of available evidence, three taxa were recognized in the S. delicatula group. It is necessary to perform further studies with cytological evidence and more samples of S. delicatula from type locality in order to obtain a better understanding of the species delimitation. We suggested that the taxonomic work of Selaginella should focus on the closely related species and multiple lines of evidence should be considered, including morphological characters, cytological evidence, molecular data (nuclear and chloroplast DNA markers), and geographical distribution.

Key words: 26S nrDNA, pgiC, chloroplast markers, lycophytes, Selaginella delicatula group