Lumme Jaakko, Ziętara Marek S, Lebedeva Dar'ya
Department of Biology, University of Oulu, 90014, Oulu, Finland.
Department of Molecular Evolution, University of Gdańsk, Wita Stwosza St., 59, 80-308, Gdańsk, Poland.
Syst Parasitol. 2017 Feb;94(2):183-200. doi: 10.1007/s11230-016-9696-y. Epub 2017 Jan 27.
Phylogenetic analyses including four allopatric species of Gyrodactylus von Nordmann, 1832 on the Eurasian minnow Phoxinus phoxinus (L.) (Cyprinidae) revealed incongruence between the nuclear ITS1-5.8S-ITS2 and mitochondrial cox1 phylogenies due to ancient hybridisation. Gyrodactylus pannonicus Molnár, 1968 was sampled close to its type-locality, the upper reaches of River Tisza, tributary of Danube in the Black Sea Basin. Faunistic search detected three new related species with maximum composite likelihood distances in cox1 between 16.8-23.2% (tentatively 1.3 to 1.8 My of divergence). Gyrodactylus albolacustris n. sp. recorded in the White Sea Basin, eastern Baltic Basin and Mongolia was close to G. pannonicus in the nuclear ITS (divergence of 0.9%), but diverged in cox1 by 19.8%. The Mongolian isolate of G. albolacustris n. sp. diverged from the European isolates in cox1 by 8.9%, suggesting 0.7 My of isolation. The two other new species differed from G. pannonicus by >4% in ITS and some large indels in ITS1, and by >20% in cox1. Gyrodactylus danastriae n. sp. was found in River Strwiąż, a tributary of the River Dniester (Black Sea Basin) and was characterised by smaller size of anchors and by 29-41 bp dimorphic insertion in ITS1. Gyrodactylus botnicus n. sp. is considered endemic in the Baltic Basin, but was also found in the White Sea Basin as a postglacial immigrant, where it had hybridised with G. albolacustris n. sp. in spite of the high divergence in ITS (3.9%) and cox1 (22%). The discordant nuclear and mitochondrial phylogenies revealed an ancient mitochondrial introgression: G. albolacustris n. sp. was derived from a hybridisation combining proto-pannonicus ITS with proto-danastriae mitochondria, perhaps 1.3 My ago. The postglacial hybridisation of G. albolacustris n. sp. (as the donor of mtDNA and ITS) and G. botnicus n. sp. (donor of the ITS) offered a model of shuffling of the genomic components: the process of the homogenisation and stabilisation of nuclear ITS (concerted evolution) and the lineage sorting has hardly begun.
系统发育分析涵盖了1832年命名的寄生于欧亚米诺鱼（Phoxinus phoxinus (L.)，鲤科）上的四种异域分布的三代虫属（Gyrodactylus von Nordmann）物种，结果显示，由于古老的杂交事件，核糖体DNA的内转录间隔区1-5.8S-内转录间隔区2（ITS1-5.8S-ITS2）与线粒体细胞色素c氧化酶亚基I（cox1）的系统发育关系不一致。1968年命名的潘诺尼亚三代虫（Gyrodactylus pannonicus Molnár）样本采自其模式产地附近，即黑海流域多瑙河支流蒂萨河的上游。通过动物区系调查发现了三个新的近缘物种，其cox1基因的最大复合似然距离在16.8%-23.2%之间（推测分歧时间为130万至180万年）。记录于白海流域、波罗的海东部流域和蒙古的白海三代虫新种（Gyrodactylus albolacustris n. sp.），其核糖体ITS基因与潘诺尼亚三代虫接近（分歧率为0.9%），但cox1基因分歧率为19.8%。白海三代虫新种蒙古分离株与欧洲分离株在cox1基因上的分歧率为8.9%，表明隔离时间为70万年。另外两个新物种在ITS基因上与潘诺尼亚三代虫的差异大于4%，ITS1存在一些大的插入/缺失，在cox1基因上的差异大于20%。发现于德涅斯特河（黑海流域）支流斯特维亚日河的达纳斯特里亚三代虫新种（Gyrodactylus danastriae n. sp.），其特征是锚的尺寸较小，ITS1有29 - 41 bp的二态插入。博特尼亚三代虫新种（Gyrodactylus botnicus n. sp.）被认为是波罗的海流域的特有物种，但作为冰期后的移民也在白海流域被发现，尽管其ITS基因（3.9%）和cox1基因（22%）分歧很大，但它在那里与白海三代虫新种发生了杂交。核基因和线粒体基因系统发育的不一致揭示了一个古老的线粒体基因渗入事件：白海三代虫新种可能在130万年前由原始潘诺尼亚三代虫的ITS基因与原始达纳斯特里亚三代虫的线粒体基因杂交形成。白海三代虫新种（作为线粒体DNA和ITS的供体）与博特尼亚三代虫新种（ITS的供体）的冰期后杂交提供了一个基因组组分重排的模型：核ITS基因的同质化和稳定化过程（协同进化）以及谱系分选过程几乎尚未开始。
