鳞毛蕨科植物的系统发育:叶绿体rbcL序列的证据

Phylogenetic analysis of Dryopteridaceae based on chloroplast rbcL sequences

运用MEGA2和MrBayes3.0b4软件包对105种鳞毛蕨类及近缘植物(其中新测定36种)的叶绿体DNArbcL基因序列进行系统发育分析,探讨了其主要分类群(属级水平)的系统演化关系。用最大简约法、邻接法和贝叶斯分析方法构建的系统树基本一致,结果显示:(1)秦仁昌系统所定义的鳞毛蕨科Dryopteridaceae,除了拟贯众属Cyclopeltis外,均包含在两个单系群之中,支持鳞毛蕨族Dryopterideae和耳蕨族Polysticheae的成立;但是鳞毛蕨族还包含秦仁昌系统所定义的球盖蕨科Peranemaceae和三叉蕨科Tectariaceae肋毛蕨属Ctenitis的部分种类;耳蕨族还包含产于美洲的Phanerophlebia属和Polystichopsis属;确认石盖蕨属Lithostegia属鳞毛蕨族的成员,且与复叶耳蕨属Arachniodes具有较近的亲缘关系。(2)拟贯众属与所分析的其他任何鳞毛蕨类植物的关系都比较疏远,单独为一支。(3)秦仁昌系统所定义的球盖蕨科与肉刺蕨属Nothoperanema聚成一个分支,属于鳞毛蕨族的成员。(4)鳞毛蕨属Dryopteris为多系类群,耳蕨属Polystichum和贯众属Cyrtomium均为并系类群。(5)黔蕨属Phanerophlebiopsis、毛枝蕨属Leptorumohra和石盖蕨属与复叶耳蕨属构成一支;柳叶蕨属Cyrtogonellum与Polystichum属和Cyrtomium属的部分种类聚成一支;肉刺蕨属与球盖蕨科及鳞毛蕨属的部分种类聚成一支。对鳞毛蕨科的系统关系、球盖蕨科与鳞毛蕨科的系统关系、肋毛蕨属与鳞毛蕨科的系统关系以及中国或亚洲特有属(拟贯众属、肉刺蕨属、黔蕨属、毛枝蕨属、石盖蕨属和柳叶蕨属)的系统位置进行了讨论。

Dryopteridoid fems are distributed all over the world, but China and its adjacent regions have the highest species diversity, so China is a key region to study their phylogenetic relationships and evolutionary history. In this study, chloroplast rbcL sequences from 105 species of Dryopteridaceae and their relative lineages were used to reconstruct the phylogenetic trees using the MEGA2 and MrBayes 3.064 software. The phylogenetic relationships were inferred using the neighbor-joining, maximum-parsimony and Bayesian analysis, and three methods produced trees with largely congruent topology. These trees reveal that： （1） the species of the Dryopteridaceae in the classification of Ching except for those in Cyclopeltis are divided into two monophyletic groups corresponding to the two tribes, Dryopterideae Ching and Polysticheae Ching, but the genus Lithostegia should be transferred from Polysticheae to Dryopterideae, and the scopes of the two tribes should be extended： the tribe Dryopterideae includes the family Peranemaceae and some species of Ctenitis （a genus of the family Tectariaceae in Ching＇s classification）, and the tribe Polysticheae includes the American Phanerophlebia and Polystichopsis; （2） Cyclopeltis is isolated from all the other species of Dryopteridaceae and their relative lineages; （3） the family Peranemaceae in Ching＇s classification may not be a natural group, and should be included in tribe Dryopterideae, and is closely related to Nothoperanema; （4） Cyrtomium and Polystichum are both resolved as paraphyletic, and Dryopteris polyphyletic; （5） Phanerophlebiopsis, Leptorumohra and Lithostegia are closely related to Arachniodes; Cyrtogonellum and some species of Polystichum and of Cyrtomium form a clade; Nothoperanema are closely related to Peranemaceae and some species of Dryopteris. The relationships among genera of Dryopteridaceae, the relationship between Peranemaceae and Dryopteridaceae, and that between Ctenitis and Dryopteridaceae, and the systemic positions of the genera endemic to China or Asia （ Cyclopeltis, Nothoperanema, Phanerophlebiopsis, Leptorumohra, Lithostegia and Cyrtogonellum） are also discussed. Our phylogenetic analyses are based on only rbcL sequence data, so the results should be further confirmed using other lines of evidence.