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Abstract：
Broad tapeworms (Diphyllobothriidea) are parasites whose adults are capable of infecting a wide range of freshwater, marine and terrestrial tetrapods including humans. Previous works examining the evolution of habitat and host use in this group have been hampered by the lack of a well-resolved phylogeny. In order to produce a robust phylogenetic framework for diphyllobothriideans, we sequenced the complete mitochondrial genome of 13 representatives, carefully chosen to cover the major clades, and two outgroup species representing the Spathebothriidea and Haplobothriidea. In addition, complementary data from the nuclear ribosomal operon was sequenced for 10 representative taxa. Mitogenomes and ssrDNA and lsrDNA were used towards elucidating the phylogenetic framework for the Diphyllobothriidea. The Cephalochlamydidae is confirmed as the earliest diverging diphyllobothriidean lineage, and Solenophoridae and Diphyllobothriidae are sister groups. We infer a probable freshwater origin of the diphyllobothriideans. The ancestral condition for life cycle complexity could not be unambiguously resolved. However, we infer exclusive use of a three-host life cycle following the origin of the Solenophoridae + Diphyllobothriidae. Regarding definitive host use, although we infer reptiles as the most likely ancestral condition, this result should be revisited with a more densely sampled phylogeny in future studies. Freshwater habitat is used by the early diverging lineages within the Solenophoridae + Diphyllobothriidae clade. For the latter, habitat use shifts between freshwater and marine environments, and definitive host use includes marine and terrestrial mammals and birds. We use mitochondrial genomes to distinguish Schistocephalus species occurring in different species of sticklebacks and demonstrate conspecificity of Ligula cf. intestinalis specimens collected from two Fennoscandian ringed seal subspecies.
摘要：
广泛的tape虫（Diphyllobothriidea）是寄生虫，其成虫能够感染多种淡水，包括人类在内的海洋和陆地四足动物。由于缺乏解决良好的系统发育，因此先前研究该群体中栖息地和寄主使用的研究工作受到了阻碍。为了产生一个强大的系统进化框架，我们对13个代表的完整线粒体基因组进行了测序，精心挑选来覆盖主要分支，和两个代表Spatebothriidea和Haplobothriidea的外群物种。此外,对10个代表性分类单元的核核糖体操纵子的互补数据进行了测序。有丝分裂基因组，ssrDNA和lsrDNA用于阐明二叶虫的系统发育框架。头孢霉素科被确认为最早的发散的二叶虫谱系，亚科和双叶虫科是姐妹组。我们推断二叶草可能是淡水来源。生命周期复杂性的祖先条件无法明确解决。然而,我们推断，在SolenophoridaeDiphyllobothriidae的起源之后，三宿主生命周期的独家使用。关于确定的主机使用，尽管我们推断爬行动物是最可能的祖先状况，在未来的研究中，应该通过更密集采样的系统发育来重新审视这一结果。淡水栖息地被SolenophoridaeDiphyllobothriidae进化枝的早期发散谱系所使用。对于后者,栖息地在淡水和海洋环境之间的使用转移，确定的宿主用途包括海洋和陆地哺乳动物和鸟类。我们使用线粒体基因组来区分不同种类的棘背鱼中发生的血头菌物种，并证明了Ligulacf的同特异性。从两个Fennoscandian环状海豹亚种收集的肠标本。
