title: Mitochondrial phylogeny of the genus Echinococcus (Cestoda: Taeniidae) with emphasis on relationships among Echinococcus canadensis genotypes.
abstract: The mitochondrial genomes of the genus Echinococcus have already been sequenced for most species and genotypes to reconstruct their phylogeny. However, two important taxa, E. felidis and E. canadensis G10 genotype (Fennoscandian cervid strain), were lacking in the published phylogeny. In this study, the phylogeny based on mitochondrial genome sequences was completed with these taxa. The present phylogeny highly supports the previous one, with an additional topology showing sister relationships between E. felidis and E. granulosus sensu stricto and between E. canadensis G10 and E. canadensis G6/G7 (closely related genotypes referred to as camel and pig strains, respectively). The latter relationship has a crucial implication for the species status of E. canadensis. The cervid strain is composed of two genotypes (G8 and G10), but the present phylogeny clearly suggests that they are paraphyletic. The paraphyly was also demonstrated by analysing the complete nucleotide sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) of E. canadensis genotypes from various localities. A haplotype network analysis using the short cox1 sequences from worldwide isolates clearly showed a close relatedness of G10 to G6/G7. Domestic and sylvatic life cycles based on the host specificity of E. canadensis strains have been important for epidemiological considerations. However, the taxonomic treatment of the strains as separate species or subspecies is invalid from a molecular cladistic viewpoint.
authors.affiliation: Department of Parasitology, Asahikawa Medical University, Asahikawa, Hokkaido 078-8510, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Nakao
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yanagida
authors.forename: Sergey
authors.initials: S
authors.lastname: Konyaev
authors.forename: Antti
authors.initials: A
authors.lastname: Lavikainen
authors.forename: Valeriy A
authors.initials: VA
authors.lastname: Odnokurtsev
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Zaikov
authors.forename: Akira
authors.initials: A
authors.lastname: Ito
mesh_terms: D000818:Animals; D002162:Camelus / Q000469:parasitology; D018509:DNA, Helminth / Q000145:classification / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000145:classification / Q000235:genetics*; D004443:Echinococcosis / Q000175:diagnosis / Q000469:parasitology; D004446:Echinococcus / Q000145:classification / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000145:classification / Q000235:genetics*; D054629:Genome, Mitochondrial; D005838:Genotype; D058507:Host Specificity; D006801:Humans; D017720:Molecular Epidemiology; D010802:Phylogeny; D013045:Species Specificity; D013552:Swine / Q000469:parasitology
chemical_list: D018509:DNA, Helminth; D004272:DNA, Mitochondrial; D003576:Electron Transport Complex IV