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A molecular phylogeny of the genus Echinococcus
J Bowles1, D Blair, D P McManus
1Molecular Parasitology Unit, Queensland Institute of Medical Research, Bancroft Centre, Brisbane, Australia.
Parasitology
|April 1, 1995
Summary
Genetic analysis of Echinococcus species reveals E. granulosus is not a single species but comprises at least three diverse groups. This suggests a taxonomic revision of the Echinococcus genus is necessary.
Area of Science:
- Molecular Biology
- Parasitology
- Evolutionary Genetics
Background:
- The genus Echinococcus is of significant veterinary and medical importance.
- Current classification of Echinococcus species, particularly E. granulosus, is based on limited data.
Purpose of the Study:
- To resolve the phylogenetic relationships among species and strains within the genus Echinococcus.
- To investigate the evolutionary diversity of Echinococcus strains using molecular data.
Main Methods:
- Analysis of three nucleotide data sets: mitochondrial COI, mitochondrial ND1, and nuclear ribosomal ITS1.
- Detection of mitochondrial heteroplasmy in an E. granulosus strain.
- Identification of multiple ITS1 sequence variants within a single isolate.
Main Results:
- The data do not support E. granulosus as a single valid species, indicating at least three distinct evolutionary groups (sheep, bovine, horse strains).
- Molecular distances between these E. granulosus groups are comparable to or greater than distances between recognized species.
- E. multilocularis may not be distinct from E. granulosus, while E. vogeli and E. oligarthrus appear distinct and distantly related.
Conclusions:
- A taxonomic revision of the genus Echinococcus is strongly indicated by the molecular evidence.
- The current species delineation within Echinococcus requires re-evaluation.
- The evolutionary history of Echinococcus is more complex than previously understood.