Rindi Fabio, Lam Daryl W, López-Bautista Juan M
Department of Biological Sciences, The University of Alabama, P.O. Box 870345, 425 Scientific Collections Bldg., Tuscaloosa, AL 35487-0345, USA.
Mol Phylogenet Evol. 2009 Aug;52(2):329-39. doi: 10.1016/j.ympev.2009.01.009.
Subaerial green microalgae represent a polyphyletic complex of organisms, whose genetic diversity is much higher than their simple morphologies suggest. The order Trentepohliales is the only species-rich group of subaerial algae belonging to the class Ulvophyceae and represents an ideal model taxon to investigate evolutionary patterns of these organisms. We studied phylogenetic relationships in two common genera of Trentepohliales (Trentepohlia and Printzina) by separate and combined analyses of the rbcL and 18S rRNA genes. Trentepohlia and Printzina were not resolved as monophyletic groups. Three main clades were recovered in all analyses, but none corresponded to any trentepohlialean genus as defined based on morphological grounds. The rbcL and 18S rRNA datasets provided congruent phylogenetic signals and similar topologies were recovered in single-gene analyses. Analyses performed on the combined 2-gene dataset inferred generally higher nodal support. The results clarified several taxonomic problems and showed that the evolution of these algae has been characterized by considerable morphological convergence. Trentepohlia abietina and T. flava were shown to be separate species from T. aurea; Printzina lagenifera, T. arborum and T. umbrina were resolved as polyphyletic taxa, whose vegetative morphology appears to have evolved independently in separate lineages. Incongruence between phylogenetic relationships and traditional morphological classification was demonstrated, showing that the morphological characters commonly used in the taxonomy of the Trentepohliales are phylogenetically irrelevant.
气生绿色微藻是一个多系的生物复合体，其遗传多样性远高于其简单形态所显示的。橘色藻目是属于绿藻纲的唯一物种丰富的气生藻类群，是研究这些生物进化模式的理想模式分类单元。我们通过对rbcL和18S rRNA基因进行单独和联合分析，研究了橘色藻目中两个常见属（橘色藻属和普林茨藻属）的系统发育关系。橘色藻属和普林茨藻属未被解析为单系类群。在所有分析中都恢复了三个主要分支，但没有一个与基于形态学定义的任何橘色藻目属相对应。rbcL和18S rRNA数据集提供了一致的系统发育信号，并且在单基因分析中恢复了相似的拓扑结构。对联合的双基因数据集进行的分析推断出总体上更高的节点支持率。结果澄清了几个分类学问题，并表明这些藻类的进化具有相当程度的形态趋同特征。已证明阿比蒂纳橘色藻和黄橘色藻与金色橘色藻是不同的物种；拉氏普林茨藻、树状普林茨藻和荫生普林茨藻被解析为多系分类单元，其营养形态似乎在不同的谱系中独立进化。系统发育关系与传统形态分类之间存在不一致，表明橘色藻目分类学中常用的形态特征在系统发育上是不相关的。
