Multilocus phylogenetic analyses reveal that habitat selection drives the speciation of Didymozoidae (Digenea) parasitizing Pacific and Atlantic bluefin tunas
Multilocus phylogenetic analyses reveal that habitat selection drives the speciation of Didymozoidae (Digenea) parasitizing Pacific and Atlantic bluefin tunas
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多位点系统发育分析表明，栖息地选择驱动了寄生于太平洋和大西洋蓝鳍金枪鱼的 Didymozoidae (Digenea) 的物种形成
作者：
I. Mladineo;N. Bott;Barbara F. Nowak;Barbara A. Block
摘要 野生和养殖蓝鳍金枪鱼的寄生虫群落表现出显着的多样性。其中，最普遍和最丰富的是双殖纲（Monticelli，1888）（Trrematoda，Digenea），被认为是分类学上最复杂的双殖纲科之一。本研究的目的是评估太平洋金枪鱼 (Thunnus orientalis) 和大西洋蓝鳍金枪鱼 (T. thynnus) 的系统发育结构，以增加我们对双鲔类动物地理学的了解，并确定可成功用作种群评估研究生物标签的物种。在本分析中，我们使用了 2 个核核糖体 DNA 基因座、28S 基因的一部分和第二个内转录间隔区 (ITS-2) 以及线粒体细胞色素 c 氧化酶亚基 1 基因 (cox1) 的一部分。在大多数寄生群体中，形态是构建系统发育关系的主要因素。然而，在极少数情况下，栖息地被认为是影响寄生虫进化的主要因素。在它们的进化过程中，双甲虫已经在其宿主的许多不同地点传播和栖息，殖民外部以及严格的内部生态位。我们的数据表明，栖息地选择一直是塑造双双模动物系统发育关系的主导力量。对于 2 个双鞭毛虫物种（D. wedli 和 D. palati），cox1 序列表明墨西哥和亚得里亚海种群之间的种内差异。
SUMMARY Parasite communities of wild and reared bluefin tuna display remarkable diversity. Among these, the most prevalent and abundant are the Didymozoidae (Monticelli, 1888) (Trematoda, Digenea), considered one of the most taxonomically complex digenean families. The aim of this study was to evaluate phylogenetic structure of Didymozoidae occurring in Pacific (Thunnus orientalis) and Atlantic bluefin tuna (T. thynnus) in order to increase our knowledge of didymozoid zoogeography and identify species that could successfully be employed as biological tags for stock assessment studies. For the present analyses we used 2 nuclear ribosomal DNA loci, part of the 28S gene and the second internal transcribed spacer (ITS-2) as well as a portion of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1). In most parasitic groups, morphology is the primary factor in the structuring of phylogenetic relationships. In rare examples, however, habitat has been suggested as a primary factor affecting parasite evolution. During their evolution, didymozoids have spread and inhabited a remarkable number of different sites in their hosts, colonizing exterior as well as strictly interior niches. Our data suggest that habitat selection has been the leading force in shaping didymozoid phylogenetic relationships. For 2 didymozoid species (D. wedli and D. palati), cox1 sequences indicate intraspecific differences between Mexican and Adriatic populations.