最大似然法和贝叶斯推论与似然比检验探讨泽泻目系统发育关系

Maximum likelihood, Bayesian inference and likelihood ratio tests in the molecular phylogeny of Alismatales

关键词:  最大似然法  贝叶斯推论  似然比检验  泽泻目系统发育分析  rbcL序列

Key words:  maximum likelihood(ML)  Bayesian inference(BI)  Hierarchical likelihood ratio tests(hLRTs)  molecular phylogeny of Alismatales  rbcL

摘要:

应用最大似然法(ML)、贝叶斯推论(BI)、邻接法(NJ)和似然比检验(hLRTs)进行泽泻目分子系统学研究。所用的rbcL基因序列代表了泽泻目14科46属以及作为外类群的6相关属。研究结果表明,^*等级制似然比检验表明泽泻目rbcL序列最适合的DNA进化模型为GTR+I+G,最大似然法、贝叶斯法和邻接法构建的系统发育树拓扑结构相似,没有显著的差异,但贝叶斯树支持率较高; 泽泻目为一单系类群,由两个主要谱系分支构成,深层分布格局由5个主要分支构成。基于分子系统发育树,文中对泽泻目科间、水鳖科+茨藻科、泽泻科+花蔺科+黄花蔺科、和“Cymodoeaceae complex”的系统发育关系进行了讨论。研究结果还表明,泽泻目系统发育关系可能还需要更多的证据进一步的澄清。

Abstract:

Maximum likelihood,Bayesian inference,Neighbor Joining and Hierarchical likelihood ratio tests were employed to study the phylogeny of Alismatales. 52 rbcL sequences were used in the analysis to represent 14 families 46 genera,and 6 related genera as outgroup. Hierarchical likelihood ratio tests showed that GTR+I+G could be the best evolutionary model for rbcL dataset,and the topology of maximum likelihood tree was similar to those of Bayesian tree and Neighbor Joining tree,but Bayesian tree giving higher support values; Alismatales could be composed of two major clades and further divided into five clades. The phylogenetic relationship of “families of Alismatales”,“Hydrocharitaceae + Najadaceae”,“Alismataceae + Butomataceae + Limnocharitaceae”,and “Cymodoeaceae complex” were discussed based on the molecular phylogenetic trees. The result also showed that more researches were needed to explain phylogeny of Alismatales.