Genetic relationships among species ofContracaecumRailliet & Henry, 1912 andPhocascarisHöst, 1932 (Nematoda: Anisakidae) from pinnipeds inferred from mitochondrialcox2sequences, and congruence with allozyme data (original) (raw)
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Parasite, 2008
The genetic relationships among 11 taxa, belonging to the genus Contracaecum (C. osculatum A, C. osculatum B, C. osculatum (s.s.), C. osculatum D, C. osculatum E, C. osculatum baicalensis, C. mirounga, C. radiatum, C. ogmorhini (s.s.), C. margolisi) and Phocascaris (Phocascaris cystophorae), parasites as adults of seals, were inferred from sequence analysis (519 bp) of the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2) gene. Phylogenetic analyses obtained from Parsimony (MP) and Neighbour-Joining (NJ) K2P distance values generated similar topologies, each well supported at major nodes. All analyses delineated two main clades: the first encompassing the parasites of the phocid seals, i.e. the C. osculatum species complex, C. osculatum baicalensis, C. mirounga and C. radiatum, with the latter two species forming a separate subclade; the second including the parasites of otarids, i.e. C. ogmorhini (s.s.) and C. margolisi. An overall high congruence between mtDNA inferred tree topologies and those produced from nuclear data sets (20 allozyme loci) was observed. Comparison of the phylogenetic hypothesis here produced for Contracaecum spp. plus Phocascaris with those currently available for their definitive hosts (pinnipeds) suggests parallelism between hosts and parasite phylogenetic tree topologies.
Genetic Relationships Among Species of Contracaecum Railliet
Parasite, 2008
Phocascaris (Phocascaris cystophorae), parasites as adults of seals, were inferred from sequence analysis (519 bp) of the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2) gene. Phylogenetic analyses obtained from Parsimony (MP) and Neighbour-Joining (NJ) K2P distance values generated similar topologies, each well supported at major nodes. All analyses delineated two main clades: the first encompassing the parasites of the phocid seals, i.e. the C. osculatum species complex, C. osculatum baicalensis, C. mirounga and C. radiatum, with the latter two species forming a separate subclade; the second including the parasites of otarids, i.e. C. ogmorhini (s.s.) and C. margolisi. An overall high congruence between mtDNA inferred tree topologies and those produced from nuclear data sets (20 allozyme loci) was observed. Comparison of the phylogenetic hypothesis here produced for Contracaecum spp. plus Phocascaris with those currently available for their definitive hosts (pinnipeds) suggests parallelism between hosts and parasite phylogenetic tree topologies.
Journal of Parasitology, 2006
The genetic relationships among 9 taxa of Anisakis Dujardin, 1845 (A. simplex (sensu stricto), A. pegreffii, A. simplex C., A. typica, A. ziphidarum, A. physeteris, A. brevispiculata, A. paggiae, and Anisakis sp.) were inferred from sequence analysis (629 bp) of the mitochondrial cox2 gene. Genetic divergence among the considered taxa, estimated by p-distance, ranged from p = 0.055, between sibling species of the A. simplex complex, to p = 0.12, between morphologically differentiated species, i.e., A. ziphidarum and A. typica. The highest level was detected when comparing A. physeteris, A. brevispiculata, and A. paggiae versus A. simplex complex (on average p = 0.13) or versus A. typica (on average p = 0.14). Sequence data from the newly identified Anisakis sp. poorly aligned with other Anisakis species but was most similar to A. ziphidarum (p = 0.08). Phylogenetic analyses based upon Parsimony and Bayesian Inference, as well as phenetic analysis based upon Neighbor-Joining p-distance values, generated similar tree topologies, each well supported at major nodes. All analyses delineated two main claides, the first encompassing A. physeteris, A. brevispiculata, and A. paggiae as a sister group to all the remaining species, and the second comprising the species of the A. simplex complex (A. simplex (s.s.1, A. pegreffii and A. simplex C), A. q p i c a , A. ziphidarum, and Anisakis sp. In general, mtDNA-based tree topologies showed high congruence with those generated from nuclear data sets (19 enzyme-loci) and with morphological data delineating adult and larval stages of the Anisakis spp.; however. precise positioning of A. typica and A. ziphidarum remain poorly resolved, though they consistently clustered in the same clade as Anisakis sp. and the A. simplex complex. Comparison of anisakid data with those currently available for their cetacean-definitive hosts suggests parallelism between host and parasite phylogenetic tree topologies.
Systematic Parasitology, 2003
Genetic variation of Contracaecum ogmorhini (sensu lato) populations from different otariid seals of the northern and southern hemisphere was studied on the basis of 18 enzyme loci as well as preliminary sequence analysis of the mitochondrial cyt b gene (260 bp). Samples were collected from Zalophus californianus in the boreal region and from Arctocephalus pusillus pusillus, A. pusillus doriferus and A. australis from the austral region. Marked genetic heterogeneity was found between C. ogmorhini (sensu lato) samples from the boreal and austral region, respectively. Two loci (Mdh-2 and NADHdh) showed fixed differences and a further three loci (Iddh, Mdh-1 and 6Pgdh) were highly differentiated between boreal and austral samples. Their average genetic distance was DNei = 0.36 at isozyme level. At mitochondrial DNA level, an average proportion of nucleotide substitution of 3.7% was observed. These findings support the existence of two distinct sibling species, for which the names C. ogmorhini (sensu stricto) and C. margolisi n. sp., respectively, for the austral and boreal taxon, are proposed. A description for C. margolisi n. sp. is provided. No diagnostic morphological characters have so far been detected; on the other hand, two enzyme loci, Mdh-2 and NADHdh, fully diagnostic between the two species, can be used for the routine identification of males, females and larval stages. Mirounga leonina was found to host C. ogmorhini (s.s.) inmixed infections with C. osculatum (s.l.) (of which C. ogmorhini (s.l.) was in the past considered to be a synonym) and C. miroungae; no hybrid genotypes were found, confirming the reproductive isolation of these three anisakid species. The hosts and geographical range so far recorded for C. margolisi n. sp. and C. ogmorhini (s.s.) are given.
Infection, Genetics and Evolution, 2014
Anisakid nematodesparasitizemainly fish, marine mammals and/orfish-eating birds, and can be transmitted to a range of fish-eating mammals, including humans, where theycan cause gastrointestinal disease linked to larval infection or allergic responses.In spite of the animal and human health significance of these parasites, there are still gaps in our understanding of thesystematics, biology, epidemiologyand ecology of anisakids.Mitochondrial (mt) DNA provides useful genetic markers for investigations in these areas, but complete mt genomic data have been lacking for most anisakids. In the present study, the mt genomesof Anisakis simplex sensu stricto and Contracaecum osculatumsensu strictowere amplified from genomic DNA by long-range polymerase chain reactionand sequenced using 454 technology. The circular mt genomesof these species were 13926 and 13823 bp, respectively, and each of them contained 12 proteincoding, 22 transfer RNA, and 2 ribosomal RNA genes consistent for members of the Ascaridida,Oxyurida, Spirurida, Rhabditida and Strongylida.Thesemt genomes provide a stepping-stone for future comparative analyses among a range of anisakids and a basis for reinvestigating their genetic relationships. In addition, these markers might be used inprospecting for cryptic species and exploring host affiliations.
Parasitology, 2000
Nuclear-encoded large-subunit ribosomal DNA sequences were used to infer a phylogenetic hypothesis for 17 taxa (16 nominal species) of the genera Contracaecum and Phocascaris. Phylogenetic trees based on these data have been used to assess the validity of the taxonomic distinction between these genera, which was based on the presence or absence of certain structural features, rather than on explicit hypotheses of evolutionary history. Phylogenetic hypotheses based on parsimony, likelihood, and neighbor-joining analyses of these sequence data strongly support the hypothesis that species of Phocascaris are nested within the clade of Contracaecum species hosted by phocid seals, and are more closely related to species of the Contracaecum osculatum complex than to other Contracaecum species. Alternative tree topologies representing Phocascaris as not nested within the C. osculatum complex were significantly worse interpretations of these sequence data. Phylogenetic analysis also provides strong support for the monophyly of all taxa (Contracaecum and Phocascaris) from phocid seals, which is consistent with Berland's (1964) proposal that such species form a natural group ; however, his proposal to recognize all species in phocid seals as Phocascaris, with all species from birds as Contracaecum would result in a paraphyletic Contracaecum, according to the molecular phylogenetic hypothesis.
Journal of Parasitology, 2000
California sea lions (Zalophus californianus) and northern fur seals (Callorhinus ursinus) are each believed to host distinct hookworm species (Uncinaria spp.). However, a recent morphometric analysis suggested that a single species parasitizes multiple pinniped hosts, and that the observed differences are host-induced. To explore the systematics of these hookworms and test these competing hypotheses, we obtained nucleotide sequences of nuclear ribosomal DNA (D2/D3 28S, D18/D19 28S, and internal transcribed spacer [ITS] regions) from 20 individual hookworms parasitizing California sea lion and northern fur seal pups where their breeding grounds are sympatric. Five individuals from an allopatric population of California sea lions were also sampled for ITS-1 and D18/D19 28S sequences. The 28S D2/D3 sequences showed no diagnostic differences among hookworms sampled from individual sea lions and fur seals, whereas the 28S D18/D19 sequences had one derived (apomorphic) character demarcating hookworms from northern fur seals. ITS sequences were variable for 7 characters, with 4 derived (apomorphic) states in ITS-1 demarcating hookworms from California sea lions. Multivariate analysis of morphometric data also revealed significant differences between nematodes representing these 2 host-associated lineages. These results indicate that these hookworms represent 2 species that are not distributed indiscriminately between these host species, but instead exhibit host fidelity, evolving independently with each respective host species. This evolutionary approach to analyzing sequence data for species delimitation is contrasted with similarity-based methods that have been applied to numerous diagnostic studies of nematode parasites.
Systematic Parasitology, 2007
Contracaecum bioccai n. sp. is described from the brown pelican Pelecanus occidentalis (L.) in northern Colombia (Totumo Marsh) based on 20 enzyme loci studied using multilocus allozyme electrophoresis. Moreover, genetic relationships between the new taxon and related congeners are presented based on allozyme data-sets and sequence analyses (519 bp) of the mtDNA-cox2 gene. Fixed allele differences were found at some of the allozyme loci analysed in comparison with other Contracaecum spp. from pelicans and cormorants [i.e. the sibling species of the C. rudolphii Hartwich, 1964 complex, C. septentrionale Kreis, 1955, C. micropa-pillatum (Stossich, 1890), C. microcephalum (Rudolphi, 1809) and C. pelagicum . The genetic distance, at the allozyme level, between C. bioccai n. sp. and its congeners ranged from D Nei = 0.80 versus C. septentrionale to D Nei = 1.40 versus C. micropapillatum. The genetic distance at the mtDNA cox-2 level ranged, on average, from K-2P = 0.12 versus the C. rudolphii species complex to K-2P = 0.15 versus C. micropapillatum. An overall concordant tree topology, obtained from UPGMA and NJ tree analyses inferred from allozyme data, as well as from MP, UPGMA and NJ inferred from mtDNA-cox2 sequence analysis, showed C. bioccai n. sp. as a separated lineage to the other Contracaecum spp. A concordant result was also obtained by PCA analysis based on both the allozyme and mtDNA cox-2 data-sets. All of the tree topologies, derived from the phylogenetic analysis inferred from both allozymes and mtDNA data-sets, were in substantial agreement and depicted C. bioccai as closely related to the sibling species of the C. rudolphii complex (C. rudolphii A and C. rudolphii B) and C. septentrionale. Morphological analysis and a differential diagnosis based on male specimens of C. bioccai, which had been genetically characterised by both allozyme markers and mtDNA sequences analysis with respect to morphologically related congeners, enabled the detection of differences in a numbers of characters, including spicule length, the morphology of the distal end of the spicule and the distribution patterns of the distal caudal papillae.
BMC Genomics, 2011
Background: The orders Ascaridida, Oxyurida, and Spirurida represent major components of zooparasitic nematode diversity, including many species of veterinary and medical importance. Phylum-wide nematode phylogenetic hypotheses have mainly been based on nuclear rDNA sequences, but more recently complete mitochondrial (mtDNA) gene sequences have provided another source of molecular information to evaluate relationships. Although there is much agreement between nuclear rDNA and mtDNA phylogenies, relationships among certain major clades are different. In this study we report that mtDNA sequences do not support the monophyly of Ascaridida, Oxyurida and Spirurida (clade III) in contrast to results for nuclear rDNA. Results from mtDNA genomes show promise as an additional independently evolving genome for developing phylogenetic hypotheses for nematodes, although substantially increased taxon sampling is needed for enhanced comparative value with nuclear rDNA. Ultimately, topological incongruence (and congruence) between nuclear rDNA and mtDNA phylogenetic hypotheses will need to be tested relative to additional independent loci that provide appropriate levels of resolution. Results: For this comparative phylogenetic study, we determined the complete mitochondrial genome sequences of three nematode species, Cucullanus robustus (13,972 bp) representing Ascaridida, Wellcomia siamensis (14,128 bp) representing Oxyurida, and Heliconema longissimum (13,610 bp) representing Spirurida. These new sequences were used along with 33 published nematode mitochondrial genomes to investigate phylogenetic relationships among chromadorean orders. Phylogenetic analyses of both nucleotide and amino acid sequence datasets support the hypothesis that Ascaridida is nested within Rhabditida. The position of Oxyurida within Chromadorea varies among analyses; in most analyses this order is sister to the Ascaridida plus Rhabditida clade, with representative Spirurida forming a distinct clade, however, in one case Oxyurida is sister to Spirurida. Ascaridida, Oxyurida, and Spirurida (the sampled clade III taxa) do not form a monophyletic group based on complete mitochondrial DNA sequences. Tree topology tests revealed that constraining clade III taxa to be monophyletic, given the mtDNA datasets analyzed, was a significantly worse result.