Maslov D A, Lukes J, Jirku M, Simpson L
Department of Biology, University of California, Los Angeles 90095-1606, USA.
Mol Biochem Parasitol. 1996 Jan;75(2):197-205. doi: 10.1016/0166-6851(95)02526-x.
Sequences of the small rRNA genes and partial sequences of the large rRNA genes were obtained by PCR amplification from a variety of vertebrate trypanosomes. The trypanosome species and hosts included Trypanosoma avium from a bird, T. rotatorium from an amphibian, T. boissoni from an elasmobranch, T. triglae from a marine teleost and T. carassii from a freshwater teleost. Phylogenetic relationships among these species and other representatives of the family Trypanosomatidae were inferred using maximum likelihood, maximum parsimony and evolutionary parsimony. The trypanosomatid tree was rooted using rRNA sequences from two species from the suborder Bodonina. All methods showed that the mammalian parasite, Trypanosoma brucei, constitutes the earliest divergent branch. The remaining trypanosomes formed a monophyletic group. Within this group, the bird trypanosome was grouped with T. cruzi, while the elasmobranch trypanosome and the two fish trypanosome species formed a group with an affinity to T. rotatorium. Our results provide no evidence for co-evolution of trypanosomatids and their hosts, either vertebrate or invertebrate. This suggests that evolution of trypanosomatids was accompanied by secondary acquisitions of hosts and habitats.
通过聚合酶链式反应（PCR）扩增，从多种脊椎动物锥虫中获得了小核糖体RNA（rRNA）基因序列和大核糖体RNA基因的部分序列。锥虫种类和宿主包括来自鸟类的禽锥虫、来自两栖动物的旋转锥虫、来自板鳃亚类的博氏锥虫、来自海洋硬骨鱼的三角锥虫和来自淡水硬骨鱼的鲫锥虫。利用最大似然法、最大简约法和进化简约法推断了这些物种与其他锥虫科代表之间的系统发育关系。锥虫树以来自波豆亚目的两个物种的rRNA序列为根。所有方法均表明，哺乳动物寄生虫布氏锥虫构成了最早分化的分支。其余锥虫形成一个单系类群。在这个类群中，鸟类锥虫与克氏锥虫归为一组，而板鳃亚类锥虫和两种鱼类锥虫物种形成了一个与旋转锥虫有亲缘关系的类群。我们的结果没有为锥虫与其脊椎动物或无脊椎动物宿主的共同进化提供证据。这表明锥虫的进化伴随着宿主和栖息地的二次获得。
