Mitochondrial DNA variation of Gyrodactylus spp. (Monogenea, Gyrodactylidae) populations infecting Atlantic salmon, grayling, and rainbow trout in Norway and Sweden

• Published in: International journal for parasitology Vol. 33; no. 13; pp. 1471 - 1478
• Main Authors: Hansen, Haakon, Bachmann, Lutz, Bakke, Tor A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2003; Elsevier Science
• Subjects: Animals; Base Sequence; Biological and medical sciences; DNA, Helminth - analysis; DNA, Mitochondrial - analysis; Ectoparasitic Infestations - parasitology; Ectoparasitic Infestations - transmission; Electron Transport Complex IV - genetics; Fish Diseases - parasitology; Fish Diseases - transmission; Fish parasite; Fundamental and applied biological sciences. Psychology; Gyrodactylosis; Gyrodactylus salaris; Gyrodactylus thymalli; Haplotypes; Host-Parasite Interactions; Invertebrates; Molecular Sequence Data; Nemathelminthia. Plathelmintha; Norway; Oncorhynchus mykiss; Oncorhynchus mykiss - parasitology; Phylogeography; Platyhelminths - enzymology; Platyhelminths - genetics; Salmo salar; Salmon - parasitology; Salmonidae - parasitology; Sequence Alignment; Sequence Analysis, DNA - methods; Species Specificity; Sweden; Systematics; Systematics. Geographical distribution; Thymallus thymallus; Norway; Sweden; Europe; Latvia; Fish parasite; Gyrodactylosis; Systematics; Gyrodactylus salaris; Phylogeography; Gyrodactylus thymalli; Host parasite relation; Genetic variability; Taxonomy; Cytochrome-c oxidase; Trematode disease; Chemotaxonomy; Mitochondrial DNA; Phylogeny; Trematoda; Freshwater environment; Cyrodactylus thymalli; Pisces; Stream; Intraspecific comparison; Geographical variation; Salmonidae; Nucleotide sequence; Enzyme; Interspecific comparison; Salmo salar; Plathelmintha; Parasitosis; Oncorhynchus mykiss; Helminthiasis; Infection; Vertebrata; Helmintha; Oxidoreductases; Ectoparasite; Invertebrata
• ISSN: 0020-7519; 1879-0135
• DOI: 10.1016/S0020-7519(03)00200-5

Approximately 800 bp of the mitochondrial cytochrome oxidase I (COI) gene were sequenced from 76 Gyrodactylus specimens of 32 salmonid host populations, i.e. from Salmo salar, Thymallus thymallus, and Oncorhynchus mykiss in Norway, Sweden and Latvia. The COI sequences indicated a substantial intraspecific differentiation of Gyrodactylus salaris and Gyrodactylus thymalli. In total, 12 haplotypes were identified which group into five well supported clades, three clades with parasites from Atlantic salmon and two clades with parasites from grayling. The basal nodes linking the five clades together are only weakly supported. Thus, there is no support for the monophyly of all G. salaris haplotypes and the monophyly of all G. thymalli haplotypes. The lack of monophyly of the mitochondrial haplotypes of G. salaris and G. thymalli may indicate that G. salaris and G. thymalli represent (i) two polytypic species or (ii) one polytypic species, or (iii) refer to a complex of more than two sibling species. The mtDNA data indicate multiple introductions of G. salaris and G. thymalli into Norway. A minimum of three independent introductions of G. salaris and two independent introductions of G. thymalli are supported. This is congruent with earlier hypotheses on the introduction of G. salaris and G. thymalli into Norway.