几种江蓠属海藻3个分子序列的系统学分析

分析了我国沿海几种常见的江蓠属(Gracilaria)海藻的18S rRNA 基因、cox2-3间隔区以及RUBISCO间隔区的分子序列，并结合GenBank现有的相关数据进行了分子系统学关系分析，为江蓠属的系统进化和分类地位提供了新的佐证。结果表明，基于cox2-3间隔区、以及 RUBISCO间隔区序列构建的MP (Maximum parsimony)进化树较为相似，而与基于18S rRNA构建的进化树略有不同。这主要是由于18S rRNA更为保守的原因；扁江蓠与脆江蓠在3个系统树中均聚合成支，显示了它们之间具有较近的亲缘关系；龙须菜与江蓠属海藻具有较远的遗传距离，在3个进化树中，龙须菜也均位于进化树的基部，单独成支，证实龙须菜并不隶属于江蓠属，且分化相对较早。

Molecular phylogeny of several common Gracilaria species inferred from 18S rRNA, cox2-3 intergenic spacer and RUBISCO spacer sequence comparisons

Sequences of three molecular markers (18S rRNA, cox2-3 intergenic spacer and RUBISCO spacer), in combination with data from GenBank, were used to analyze the phylogentic relations of Gracilaria species collected from the coast of China. Phylogenetic trees that were constructed using cox2-3 and RUBISCO spacer sequences exhibited the same pattern but differed slightly from that of the 18S rRNA-based phylogenetic tree due to a higher degree of conservation of the latter. Gracilaria textorii was sister to G. chouae in all three trees showing the close relationship between the two species. The results further confirm that the Gracilariopsis lemaneiformis does not belong to the genus Gracilaria. Results also indicate an earlier evolution status of G.lemaneiformis based on these three sequence comparisons.