Monis P T
Department of Microbiology and Immunology, University of Adelaide, SA, Australia.
Int J Parasitol. 1999 Mar;29(3):381-8. doi: 10.1016/s0020-7519(98)00216-1.
The discipline of systematics plays a central role in all branches of biology. In today's technology-orientated research world, it is important to realise the continuing value of systematics, the basic tenet of which is to combine diverse types of data to produce classifications that reflect the natural history of living organisms. Accurate classification systems are crucial in the field of parasitology, not only because they provide the means to identify species and strains of parasites, but also because they provide a framework around which a parasite's biology can be studied. The construction of such a classification system is often hampered by the parasite's biology, which may preclude the application of traditional techniques or concepts (such as morphological differentiation or the biological species concept) to delineate species. It is often the case that these difficulties can be overcome by the use of molecular systematic techniques. In this paper, it is proposed that a detailed understanding of the phylogeny of a group of organisms can be used as a basis to examine other aspects of their systematics. This is illustrated using the protozoan parasite Giardia intestinalis. Data gathered using the complementary techniques of allozyme electrophoresis and nucleotide sequencing have been used to infer the phylogenetic relationships of G. intestinalis isolated from various host species. The results, supported by biological data, suggest that G. intestinalis is a species-complex. As we move towards the year 2000, molecular systematics will play an increasingly important role in elucidating host-parasite relationships. However, its use as a taxonomic tool will require a general acceptance by parasitologists and the adoption of formal procedures to allow the description of new species by these methods. The aim of this approach is not to dismiss traditional methods, but to use them in combination with contemporary methods in the true spirit of the discipline of systematics.
分类学在生物学的各个分支中都起着核心作用。在当今以技术为导向的研究领域，认识到分类学的持续价值非常重要，其基本原则是整合各种类型的数据以产生反映生物自然历史的分类。准确的分类系统在寄生虫学领域至关重要，这不仅是因为它们提供了识别寄生虫物种和菌株的方法，还因为它们提供了一个框架，围绕这个框架可以研究寄生虫的生物学特性。构建这样一个分类系统常常受到寄生虫生物学特性的阻碍，这可能会妨碍应用传统技术或概念（如形态学分化或生物物种概念）来界定物种。通常情况下，这些困难可以通过使用分子分类学技术来克服。本文提出，对一组生物的系统发育进行详细了解可以作为研究其分类学其他方面的基础。这一点以原生动物寄生虫肠道贾第虫为例进行了说明。利用等位酶电泳和核苷酸测序这两种互补技术收集的数据，已被用于推断从各种宿主物种分离出的肠道贾第虫的系统发育关系。这些结果得到生物学数据的支持，表明肠道贾第虫是一个复合物种。随着我们迈向2000年，分子分类学在阐明宿主 - 寄生虫关系方面将发挥越来越重要作用。然而，将其用作分类工具需要寄生虫学家的普遍接受，并采用正式程序以便通过这些方法描述新物种。这种方法的目的不是摒弃传统方法，而是本着分类学学科的真正精神将它们与当代方法结合使用。
