柏木属的分类地位和物种多样性研究现状与建议

Taxonomy and diversity of the genus Cupressus:current status and recommendations

柏木属(Cupressus L.)是柏科的模式属,1753年由卡尔·林奈在其著作《植物种志》中命名,其模式种为地中海柏木(Cupressus sempervirens L.)。但是,随着越来越多的物种得以发现和描述,以及近几十年来系统发育学和群体遗传学研究的开展,柏木属的分类地位和物种数量争议不断。2011年,Christenhusz等提出现存裸子植物新的分类系统时(即克氏裸子植物系统),柏木属(Cupressus sensu Christenhusz)的概念可涵盖4个属级类群:狭义柏木属、金柏属、北美金柏属、美洲柏木属;通常广义柏木属(Cupressus sensu lato)涵盖狭义柏木属和美洲柏木属物种;而狭义柏木属(Cupressus sensu stricto)仅包含广义柏木属中分布在旧世界的物种。基于21世纪以来国内外学者对柏木属及其近缘属的研究进展,以及笔者自身的研究和野外考察经验,笔者简要综述了该属的分类地位和物种多样性。最新的系统发育基因组学证据表明,狭义柏木属为单系群且与刺柏属互为姊妹关系,二者的共同祖先与金柏属、北美金柏属、美洲柏木属的共同祖先互为姊妹关系。对一些具争议的分类处理提出了新的见解,将Cupressus rushforthii Maerki&J.Hoch降级为Cupressus austrotibetica Silba的异名,并确认剑阁柏木为大渡河柏木(Cupressus fallax Franco)和柏木(Cupressus funebris Endlicher)的杂交后代,将其拉丁名修订为Cupressus×jiangeensis N.Zhao;同时,将王氏柏木(Cupressus×wangii J.Hoch,Maerki&Rushforth)处理为剑阁柏木的异名;另外,为避免混淆,建议将西藏波密县新近发现的亚洲最高树种Cupressus austrotibetica Silba中文名修改为“西藏高柏”,将主要分布在尼泊尔的“西藏柏木”(Cupressus torulosa D.Don ex Lamb.)中文名恢复为“喜马拉雅柏”。根据目前的研究现状,狭义柏木属应包含14种,其中包括1个杂种。为确保未来柏木属物种划分的准确性和科学性,建议采用整合物种概念,在分类工作中综合考虑形态学、遗传学、生态学和生物地理学等多维度数据。新一代测序技术等前沿技术方法为柏木属系统分类与进化研究提供了强大工具,未来对狭义柏木属物种多样性及其演化历史的探索和理解还将进一步深入。

Cupressus L.,the type of Cupressaceae family,is typified by Cupressus sempervirens L.Over the years,as many other species have been discovered and described,and with advances in phylogenetics and population genetics,the taxonomy and species diversity within the genus Cupressus have been subjects of continuous debate.Traditionally,the Cupressus sensu lato includes species from true Cypresses sensu stricto and New World cypresses(Hesperocyparis Bartel&R.A.Price),while the Cupressus s.s.comprises all Old World species except the Vietnamese golden cypress(Xanthocyparis vietnamensis Farjon&T.H.Nguyên)found in Vietnam.Christenhusz et al.defined the broadest interpretation of Cupressus(Cupressus sensu Christenhusz)which encompasses four groups:true cypresses(Cupressus s.s.),Vietnamese golden cypress,Nootka cypress(Callitropsis nootkatensis(D.Don)Oerst),and New World cypresses.These ideas have been challenged by recent phylogenomic studies.Recent studies have shown that Cupressus s.l.is non-monophyletic,Cupressus s.s.is monophyletic and forms a sister group with the genus Juniperus.The common ancestor of these two is a sister group of the common ancestors of the Xanthocyparis,Callitropsis and Hesperocyparis.Based on current research,the true cypresses should encompass 14 species,including one hybrid.This paper offers new perspectives on previous contentious taxonomic treatments,for instance,reclassifying Cupressus rushforthii Maerki&J.Hoch as a synonym of Cupressus austrotibetica Silba,and confirming that Cupressus×jiangeensis N.Zhao is a hybrid offspring of the Cupressus fallax Franco and Cupressus funebris Endlicher.Additionally,Cupressus×wangii J.Hoch,Maerki&Rushforth has been reduced to a synonym of Cupressus×jiangeensis.To avoid confusion,it is recommended to rename the recently discovered tallest tree species in Bomi County,Cupressus austrotibetica,to“西藏高柏”(Xizang tall cypress)in Chinese,and the cypress predominantly found in Nepal,Cupressus torulosa D.Don ex Lamb.,is referred to as“喜马拉雅柏”(Himalayan cypress)in Chinese,instead of“西藏柏木”(Xizang Cypress).To ensure accuracy and scientific validity in future studies on species delineation within the genus,we recommend integrating multidimensional data from morphology,genetics,ecology and biogeography.This approach will help the reducing of classification confusion and support biodiversity conservation efforts more effectively.