A phylogeny based on cytochrome-c oxidase gene sequences identifies sympatric Ichthyophonus genotypes in the NE Pacific Ocean
ABSTRACT: In recent decades, evidence has accumulated to suggest that the widespread and highly variable parasite Ichthyophonus hoferi is actually a species complex. Highly plastic morphology and a general lack of defining structures has contributed to the likely underestimate of biodiversity within this group. Molecular methods are a logical next step in the description of these parasites, but markers used to date have been too conserved to resolve species boundaries. Here we use mitochondrial encoded cytochrome-c oxidase (MTCO1) gene sequences and phylogenic analysis to compare Ichthyophonus spp. isolates from several marine and anadromous fish hosts. The resulting phylogeny displays lineage separation among isolates and possible host/niche segregation not previously described. The parasite type that infects Pacific herring Clupea pallasii, Atlantic herring C. harengus, Atlantic salmon Salmo salar, and Pacific staghorn sculpin Oligocottus maculosus (Clade A) is different from that which infects Chinook salmon Oncorhynchus tshawytscha, walleye pollock Gadus chalcogrammus, Greenland halibut Reinhardtius hippoglossoides, and Pacific halibut Hippoglossus stenolepsis (Clade B). MTCO1 sequences confirmed the presence of a more divergent Ichthyophonus sp. isolated from American shad Alosa sapidissima in rivers of eastern North America (Clade C), while American shad introduced to the Pacific Ocean are infected with the same parasite that infects Pacific herring (Clade A). Currently there are no consensus criteria for delimiting species within Ichthyophonidae, but MTCO1 sequences hold promise as a potential species identifying marker and useful epizootiological tool.
Citation Information
| Publication Year | 2022 |
|---|---|
| Title | A phylogeny based on cytochrome-c oxidase gene sequences identifies sympatric Ichthyophonus genotypes in the NE Pacific Ocean |
| DOI | 10.3354/dao03677 |
| Authors | Jacob L. Gregg, Paul Hershberger, Abigail S. Neat, Hiruni T. Jayasekera, Jayde A. Ferguson, Rachel L. Powers, Maureen K. Purcell |
| Publication Type | Article |
| Publication Subtype | Journal Article |
| Series Title | Diseases of Aquatic Organisms |
| Index ID | 70233230 |
| Record Source | USGS Publications Warehouse |
| USGS Organization | Western Fisheries Research Center |
Related Content
DNA sequences from Ichthyophonid parasites
Paul Hershberger, Ph.D.
Chief - Fish Health Section
Station Leader
Rachel Powers (Former Employee)
Biological Science Technician
Maureen K Purcell, Ph.D.
Deputy Center Director
Related Content
- Data
DNA sequences from Ichthyophonid parasites
Data included are DNA sequences used to identify species boundaries among Ichthyophonus-like parasites. Sequences were generated for three gene regions from each parasite isolate. DNA sequences can be downloaded from GenBank (https://www.ncbi.nlm.nih.gov/) as text or fasta files. Accession numbers for each sequence are included in the data table (.csv file). Data includes 87 sequences (99,383 tota - Connect
Paul Hershberger, Ph.D.
Chief - Fish Health SectionStation LeaderEmailPhoneExt225Rachel Powers (Former Employee)
Biological Science TechnicianMaureen K Purcell, Ph.D.
Deputy Center DirectorEmail