Institute of Parasitology, Biology Centre of the Academy of Sciences of the Czech Republic, University of South Bohemia, Czech Republic.
Int J Parasitol. 2012;42(3):259-67. doi: 10.1016/j.ijpara.2012.01.005. Epub 2012 Feb 16.
Caryophyllidean cestodes (Platyhelminthes) represent an unusual group of tapeworms lacking serially repeated body parts that potentially diverged from the common ancestor of the Eucestoda prior to the evolution of segmentation. Here we evaluate the utility of two nuclear and two mitochondrial molecular markers (ssrDNA and lsrDNA, nad3 and cox1) for use in circumscribing generic boundaries and estimating interrelationships in the group. We show that these commonly employed markers do not contain sufficient signal to infer well-supported phylogenetic estimates due to substitution saturation. Moreover, we detected multiple trnK+nad3+trnS+trnW+cox1 haplotypes within individuals, indicating a history of gene exchange between the mitochondrial and nuclear genomes. The presence of such nuclear paralogs (i.e. numts), to our knowledge described here in cestodes for the first time, together with the results of phylogenetic, saturation and split-decomposition analyses all suggest that finding informative markers for estimating caryophyllidean evolution is unusually problematic in comparison to other major lineages of tapeworms.
Caryophyllidean 绦虫（扁形动物门）代表了一组不寻常的绦虫，它们缺乏连续重复的身体部位，这些身体部位可能在分节进化之前就从 Eucestoda 的共同祖先中分化出来了。在这里，我们评估了两种核和两种线粒体分子标记（ssrDNA 和 lsrDNA、nad3 和 cox1）在划定属界和估计该组内种间关系方面的用途。我们表明，由于替换饱和，这些常用标记物中没有包含足够的信号来推断得到良好支持的系统发育估计值。此外，我们在个体内检测到多个 trnK+nad3+trnS+trnW+cox1 单倍型，这表明线粒体和核基因组之间存在基因交换的历史。核旁系同源物（即 numts）的存在，据我们所知，这是首次在绦虫中描述，与系统发育、饱和和分裂分解分析的结果一起表明，与其他主要的绦虫谱系相比，找到用于估计 Caryophyllidean 进化的信息标记物是异常困难的。
