Müller Tobias, Philippi Nicole, Dandekar Thomas, Schultz Jörg, Wolf Matthias
Department of Bioinformatics, Biocenter, University of Würzburg, Germany.
RNA. 2007 Sep;13(9):1469-72. doi: 10.1261/rna.617107. Epub 2007 Jul 24.
Given two organisms, how can one distinguish whether they belong to the same species or not? This might be straightforward for two divergent organisms, but can be extremely difficult and laborious for closely related ones. A molecular marker giving a clear distinction would therefore be of immense benefit. The internal transcribed spacer 2 (ITS2) has been widely used for low-level phylogenetic analyses. Case studies revealed that a compensatory base change (CBC) in the helix II or helix III ITS2 secondary structure between two organisms correlated with sexual incompatibility. We analyzed more than 1300 closely related species to test whether this correlation is generally applicable. In 93%, where a CBC was found between organisms classified within the same genus, they belong to different species. Thus, a CBC in an ITS2 sequence-structure alignment is a sufficient condition to distinguish even closely related species.
给定两种生物，如何区分它们是否属于同一物种呢？对于两种差异较大的生物来说，这可能很简单，但对于亲缘关系密切的生物而言，可能极其困难且费力。因此，一种能给出明确区分的分子标记将大有裨益。内部转录间隔区2（ITS2）已被广泛用于低水平的系统发育分析。案例研究表明，两种生物之间ITS2二级结构的螺旋II或螺旋III中的补偿性碱基变化（CBC）与有性不亲和相关。我们分析了1300多个亲缘关系密切的物种，以测试这种相关性是否普遍适用。在93%的情况中，在同一属内分类的生物之间发现存在CBC时，它们属于不同的物种。因此，ITS2序列-结构比对中的CBC是区分甚至亲缘关系密切的物种的充分条件。
