Department of Biology, Syracuse University, 107 College Place, Syracuse, NY, 13244, USA; Institute of Evolutionary Biology, Ashworth Laboratories, The University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh EH9 3JT, UK.
Mol Ecol. 2014 Oct;23(19):4674-6. doi: 10.1111/mec.12892.
The goal of DNA barcoding is to enable the rapid identification of taxa from short diagnostic DNA sequence profiles. But how feasible is this objective when many evolutionary processes, such as hybridization and selective sweeps, cause alleles to be shared among related taxa? In this issue of Molecular Ecology, Percy et al. (2014) test the full suite of seven candidate plant barcoding loci in a broad geographic sample of willow species. They show exceptional plastid haplotype sharing between species across continents, with most taxa not possessing a unique barcode sequence. Using population genetic and molecular dating analyses, they implicate hybridization and selective sweeps, but not incomplete lineage sorting, as the historical processes causing widespread haplotype sharing among willow taxa. This study represents an exceptional case of how poorly barcoding can perform, and highlights methodological issues using universal organellar regions for species identification.
DNA 条形码的目标是能够通过短的诊断 DNA 序列特征快速识别分类单元。但是，当许多进化过程（如杂交和选择清除）导致等位基因在相关分类单元中共享时，这个目标的可行性如何呢？在本期《分子生态学》中，Percy 等人（2014 年）在一个广泛的柳树物种地理样本中测试了七套候选植物条形码基因座。他们发现，不同物种之间的叶绿体单倍型共享非常普遍，大多数分类单元没有独特的条形码序列。通过种群遗传和分子定年分析，他们认为杂交和选择清除，而不是不完全谱系分选，是导致柳树分类单元之间广泛的单倍型共享的历史过程。这项研究代表了条形码表现不佳的一个特殊案例，强调了使用通用细胞器区域进行物种鉴定的方法问题。
