线蕨属(水龙骨科)的系统发育研究:来自叶绿体rbcL和rps4-trnS序列的证据

Molecular phylogeny of Colysis (Polypodiaceae) based on chloroplast rbcL and rps4-trnS sequences

线蕨属Colysis植物主要分布于亚洲热带和亚热带地区,少数种类分布至非洲、澳大利亚(昆士兰)及新几内亚地区。自1849年成立以来,线蕨属的分类范畴和系统位置一直有待确定。本文利用叶绿体基因组的rbcL、rps4基因和rps4-trnS基因间隔区序列,运用最大简约法和贝叶斯方法分析了线蕨属及其近缘类群的系统演化关系。研究结果显示:(1)线蕨属和薄唇蕨属Leptochilus(含似薄唇蕨属Paraleptochilus)组成一个支持率很高的单系分支(C-LClade),但是薄唇蕨属的成员位于线蕨属的不同支系内,支持线蕨属和薄唇蕨属合并为一个属;(2)瘤蕨属Phymatosorus单独形成一个单系分支;(3)星蕨属Microsorum是一个多系类群,除Microsorium linguiforme、M.varians和M.pustulatum与马来群岛的Lecanopteris聚在一起外,其他的星蕨属成员均位于不同的支系上。本文的系统发育分析结果为线蕨属和薄唇蕨属的分类处理提供了分子系统学的证据。

Colysis （Polypodiaceae） is a genus with approximately 30 species found in Asia, Africa, Australia （restricted to Queensland）, and New Guinea, including ca. 15 species in China. The systematic position and taxonomic circumscription of Colysis has remained unresolved since its establishment in 1849. In this work we retrieved the chloroplast DNA sequences rbcL and rps4-trnS for Colysis and its closely related taxa. Two data sets-the rbcL gene and rps4-trnS region （including both the rps4 gene and the rps4-trnS intergenic spacer） were analyzed separately and together to assess phylogenetic relationships using maximum parsimony （MP） and Bayesian inference （BI）. Both separate and combined data sets yielded largely congruent results and revealed that Colysis formed a well-supported monophyletic group with Leptochilus Kaulf. （here designated as the C-L Clade）. Two Leptochilus species fell into different subclades of the C-L clade. Phymatosorus Pic. Serm. formed a distinct lineage in the current analysis. The genus Microsorum Link, as traditionally defined, was polyphyletic; while M. linguiforme, M. varians, and M. pustulatum clustered with Malaysian Lecanopteris, other microsorums were isolated in different clades. Our phylogenetic analysis suggests that Leptochilus and Colysis may better be treated as one genus.