柳属的分支系统学分析

Cladistic Analysis of the Genus Salix (Salicaceae)

基于61个广义的形态学性状,以杨属为外类群对柳属进行了分支系统学分析。经简约性分析,得到了21个同等简约的分支树,其严格一致树支持柳属为一个自然的分类群,但不支持将钻天柳属和心叶柳属从柳属中划分出去独立成属,也不支持对柳属进行属级水平上的细分,后两个结果得到孢粉学和分子系统学研究的支持。柳亚属为一个单系分支,皱纹柳亚属和黄花柳亚属也形成了一个单系分支。根据本研究的结果,建议将柳属划分为钻天柳亚属、柳亚属及黄花柳亚属3个亚属。由于较低的靴带支持率,其系统发育关系难于探讨。鉴于分支分析的一致性指数、保持性指数、各分支内部的支持率均不高,柳属的属下分类系统的划分有待进一步的研究。

The genus Salix comprises about 500 species, many of which grow in temperate zone of the Noah Hemisphere. Their variability in morphology, life form and habitats has led to many arguments and different suggestions in terms of taxonomical treatments at both species and genus levels. To understand morphological variation and phylogenetics of Salix, 29 Salix species and Chosenia arbutifolia, including most representative species in the genus Salix, and their 61 morphological characters were used for cladistic analysis. Populus plants were selected as outgroups. In this study, we got 21 equally most parsimonious cladograms of Salix and a strict consensus tree, which shows Chosenia is sister group of Salix and those two taxa form a strongly supported monophyletic clade. The results indicate that the division of Chosenia and Toisusu from Salix as independent genera and any other division on the generic level are not supported, which accords with the evidences from both palynology and molecular systematics. Three subgenem, Subgen. Salix, Subgen. Chamaetia and Subgen. Vetrix form two monophyletic clades respectively. Based on our findings, we proposed to divide Salix into three subgenem, namely Chosenia, Salix, Vetrix. Considered there exist the lower Consistency Index, Retention Index and bootstrap value in the phylogenetic tree, more research for better understanding the infrageneric system of Salix.should be fully necessary.