Molecular and morphological variation within swim bladder nematodes, Cystidicola spp

We sequenced four rDNA regions (ITS-1, ITS-2, 5.8S, and D3 region of 28S) from the parasitic nematode Cystidicola spp. from seven species of fish host and 11 locations in Canada and Finland to elucidate suspected unresolved genetic variation within the genus. A holarctic species, Cystidicola farioni...

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Bibliographic Details
Published in:Canadian journal of fisheries and aquatic sciences 2004-07, Vol.61 (7), p.1143-1152
Main Authors: Miscampbell, Allyson E, Lankester, Murray W, Adamson, Martin L
Format: Article
Language:English
Subjects:
Agnatha. Pisces
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Autoecology
Biological and medical sciences
Coregonus clupeaformis
Cryptic species
Cystidicola farionis
Cystidicola stigmatura
Fish
Freshwater
Fundamental and applied biological sciences. Psychology
Genetic diversity
Genetics
Host parasite relation
pathogenicity
Invertebrates
Life history
Molecular biology
Nature conservation
Nemathelminthia. Plathelmintha
Nematoda
Nematodes
Osmeridae
Phenotypic variations
Ribosomal DNA
Salmonoidei
Salvelinus
Speciation
Taxa
Vertebrata
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Summary:We sequenced four rDNA regions (ITS-1, ITS-2, 5.8S, and D3 region of 28S) from the parasitic nematode Cystidicola spp. from seven species of fish host and 11 locations in Canada and Finland to elucidate suspected unresolved genetic variation within the genus. A holarctic species, Cystidicola farionis from the swim bladder of Salmonidae and Osmeridae, and a nearctic species, Cystidicola stigmatura from trout and char (Salvelinus spp.), differ in life history, host and geographic range, reproductive strategy, and adult and egg morphology. These nematodes were identical at three rDNA regions (ITS-1, 5.8S, and D3); however, two ITS-2 variants were found that differed at four nucleotide positions: variant I (366 bp) was found in British Columbia populations of C. farionis and in C. stigmatura and variant II (369 bp) was found in Ontario and Finnish populations of C. farionis. These results demonstrate that two species with distinct morphology and biology can have identical rDNA sequences, while two morphologically identical isolates have different ITS-2 sequences. Thus, rDNA spacer regions may not be useful for distinguishing biologically valid species or subspecies in some nematode groups. Although phenotypic variation suggested a third undescribed species of Cystidicola from lake whitefish (Coregonus clupeaformis), rDNA analysis did not provide meaningful evidence of its uniqueness.
ISSN:0706-652X
1205-7533
DOI:10.1139/f04-064