Huyse Tine, Audenaert Vanessa, Volckaert Filip A M
Laboratory of Aquatic Ecology, Katholieke Universiteit Leuven, Ch. De Bériotstraat 32, B-3000 Leuven, Belgium.
Int J Parasitol. 2003 Dec;33(14):1679-89. doi: 10.1016/s0020-7519(03)00253-4.
Using species-level phylogenies, the speciation mode of Gyrodactylus species infecting a single host genus was evaluated. Eighteen Gyrodactylus species were collected from gobies of the genus Pomatoschistus and sympatric fish species across the distribution range of the hosts. The V4 region of the ssrRNA and the internal transcribed spacers encompassing the 5.8S rRNA gene were sequenced; by including published sequences a total of 30 species representing all subgenera were used in the data analyses. The molecular phylogeny did not support the morphological groupings into subgenera as based on the excretory system, suggesting that the genus needs systematic revisions. Paraphyly of the total Gyrodactylus fauna of the gobies indicates that at least two independent colonisation events were involved, giving rise to two separate groups, belonging to the subgenus Mesonephrotus and Paranephrotus, respectively. The most recent association probably originated from a host switching event from Gyrodactylus arcuatus, which parasitises three-spined stickleback, onto Pomatoschistus gobies. These species are highly host-specific and form a monophyletic group, two possible "signatures" of co-speciation. Host specificity was lower in the second group. The colonising capacity of these species is illustrated by a host jump from gobiids to another fish order (Anguilliformes), supporting the hypothesis of a European origin of Gyrodactylus anguillae and its intercontinental introduction by the eel trade. Thus, allopatric speciation seems to be the dominant mode of speciation in this host-parasite system, with a possible case of sympatric speciation.
利用物种水平的系统发育树，评估了感染单一宿主属的三代虫物种的物种形成模式。从分布范围内的斑头鱼属虾虎鱼和同域分布的鱼类物种中收集了18种三代虫。对小核糖体RNA的V4区域以及包含5.8S rRNA基因的内转录间隔区进行了测序；通过纳入已发表的序列，总共30个代表所有亚属的物种被用于数据分析。分子系统发育不支持基于排泄系统将形态学分组为亚属，这表明该属需要进行系统修订。虾虎鱼的整个三代虫动物区系的并系性表明至少涉及两个独立的定殖事件，产生了两个分别属于中肾三代虫亚属和副肾三代虫亚属的独立群体。最近的关联可能源于三代虫从寄生于三刺鱼的弓形三代虫宿主转换到斑头鱼属虾虎鱼。这些物种具有高度的宿主特异性，并形成一个单系类群，这是共物种形成的两个可能“特征”。第二组中的宿主特异性较低。这些物种的定殖能力通过从虾虎鱼到另一个鱼类目（鳗鲡目）的宿主跳跃得到说明，这支持了鳗三代虫起源于欧洲并通过鳗鱼贸易进行洲际引入的假说。因此，异域物种形成似乎是这个宿主 - 寄生虫系统中物种形成的主要模式，可能存在同域物种形成的情况。
