Blaxter M L, De Ley P, Garey J R, Liu L X, Scheldeman P, Vierstraete A, Vanfleteren J R, Mackey L Y, Dorris M, Frisse L M, Vida J T, Thomas W K
Institute of Cell, Animal and Population Biology, University of Edinburgh, UK.
Nature. 1998 Mar 5;392(6671):71-5. doi: 10.1038/32160.
Nematodes are important: parasitic nematodes threaten the health of plants, animals and humans on a global scale; interstitial nematodes pervade sediment and soil ecosystems in overwhelming numbers; and Caenorhabditis elegans is a favourite experimental model system. A lack of clearly homologous characters and the absence of an informative fossil record have prevented us from deriving a consistent evolutionary framework for the phylum. Here we present a phylogenetic analysis, using 53 small subunit ribosomal DNA sequences from a wide range of nematodes. With this analysis, we can compare animal-parasitic, plant-parasitic and free-living taxa using a common measurement. Our results indicate that convergent morphological evolution may be extensive and that present higher-level classification of the Nematoda will need revision. We identify five major clades within the phylum, all of which include parasitic species. We suggest that animal parasitism arose independently at least four times, and plant parasitism three times. We clarify the relationship of C. elegans to major parasitic groups; this will allow more effective exploitation of our genetic and biological knowledge of this model species.
寄生线虫在全球范围内威胁着植物、动物和人类的健康；间隙线虫大量存在于沉积物和土壤生态系统中；秀丽隐杆线虫是一种备受青睐的实验模型系统。缺乏明显的同源特征以及信息丰富的化石记录，使得我们无法为该门推导一个一致的进化框架。在此，我们利用来自广泛线虫种类的53个小亚基核糖体DNA序列进行了系统发育分析。通过该分析，我们能够使用一个共同的衡量标准来比较动物寄生、植物寄生和自由生活类群。我们的结果表明，趋同形态进化可能广泛存在，并且目前线虫纲的高级分类需要修订。我们在该门内识别出五个主要分支，所有这些分支都包括寄生物种。我们认为动物寄生至少独立出现了四次，植物寄生出现了三次。我们阐明了秀丽隐杆线虫与主要寄生类群的关系；这将使我们能够更有效地利用对这个模型物种的遗传和生物学知识。
