弯枝藻属rbcL基因的适应性进化分析

Adaptive Evolutionary Analysis of the rbcL Gene from Compsopogon (Rhodophyta)

摘要:

为探讨淡水红藻的叶绿体基因及其适应性进化特征，选取弯枝藻属（Compsopogon）及相近外类群的rbcL基因共17条，利用PAML 4.9软件，对弯枝藻属rbcL基因编码蛋白进行生物信息学分析，并分别采用分支模型、位点模型以及分支-位点模型对基因的选择位点进行检测。结果表明，弯枝藻属rbcL基因编码蛋白的二级结构主要由α螺旋和β折叠构成，结构稳定。采用最大似然法构建的系统发育树表明，内类群为单一物种，分为3个小分支，具有一定地理分布规律。在3种进化模型中均未检测到统计上显著的正选择位点，表明绝大多数位点处于负选择压力下。因此，弯枝藻属rbcL基因未发生适应性进化。

Abstract:

In order to reveal the chloroplast gene and adaptive evolution characters of Rhodophyta, the 17 rbcL genes of Compsopogon and the similar group of freshwater red algae were selected, the bioinformatics of proteins encoded by rbcL genes of Compsopogon were analyzed by using software PAML4.9, and the selection sites of genes were detected by using branch model, site model and branch-site models. The results showed that the secondary structure of protein encoded by rbcL of Compsopogon was mainly composed of α helix and β folding, so its structure was very stable. The phylogenetic tree with the maximum likelihood method showed that the inner group had only one species, could be divided into three small branches, and they had obvious geographical distribution. No significant positively selected sites were detected under all three evolutionary models, indicating that most of the sites were under negative selection pressure. Therefore, there is no adaptive evolution of rbcL gene in Compsopogon.