Biodiversity Institute of Ontario, University of Guelph, Guelph, Ontario, Canada N1G 2W1, Department of Vertebrate Zoology, Biological Faculty, Lomonosov Moscow State University, Moscow 119121, Russia.
Mol Ecol Resour. 2008 Mar;8(2):235-46. doi: 10.1111/j.1471-8286.2007.01964.x.
Although a mitochondrial DNA barcode has been shown to be of great utility for species identification and discovery in an increasing number of diverse taxa, caution has been urged with its application to one of the most taxonomically diverse vertebrate groups - the amphibians. Here, we test three of the perceived shortcomings of a CO1 DNA barcode's utility with a group of Holarctic amphibians: primer fit, sequence variability and overlapping intra- and interspecific variability. We found that although the CO1 DNA barcode priming regions were variable, we were able to reliably amplify a CO1 fragment from degenerate primers and primers with G-C residues at the 3' end. Any overlap between intra- and interspecific variation in our taxonomic sampling was due to introgressive hybridization (Bufo/Anaxyrus), complex genetics (Ambystoma) or incomplete taxonomy (Triturus). Rates of hybridization and species discovery are not expected to be greater for amphibians than for other vertebrate groups, and thus problems with the utility of using a single mitochondrial gene for species identification will not be specific to amphibians. Therefore, we conclude that there is greater potential for a CO1 barcode's use with amphibians than has been reported to date. A large-scale effort to barcode the amphibians of the world, using the same primary barcode region of CO1, will yield important findings for science and conservation.
虽然线粒体 DNA 条码在越来越多的不同分类群的物种鉴定和发现中显示出巨大的效用，但在应用于分类群最多样化的脊椎动物之一——两栖动物时，需要谨慎。在这里，我们用一组全北极两栖动物来测试 CO1 DNA 条码实用性的三个被认为的缺点：引物适配性、序列变异性和重叠的种内和种间变异性。我们发现，尽管 CO1 DNA 条码的引物结合区域是可变的，但我们能够使用简并引物和 3' 端具有 G-C 残基的引物可靠地扩增 CO1 片段。在我们的分类采样中，种内和种间变异之间的任何重叠都是由于渐渗杂交（Bufo/Anaxyrus）、复杂的遗传学（Ambystoma）或不完全的分类学（Triturus）造成的。杂交和物种发现的速度预计不会在两栖动物中比在其他脊椎动物中更高，因此，使用单一线粒体基因进行物种鉴定的实用性问题不会是两栖动物所特有的。因此，我们得出结论，CO1 条码在两栖动物中的应用潜力比迄今为止报道的要大。使用 CO1 的相同主要条码区域对世界范围内的两栖动物进行大规模的条码标记，将为科学和保护做出重要发现。
