Comparisons of Two Polymorphic Species of Ostertagia and Phylogenetic Relationships within the Ostertagiinae (Nematoda: Trichostrongyloidea) Inferred from Ribosomal DNA Repeat and Mitochondrial DNA Sequences

Authors

Dante S. Zarlenga, Agricultural Research Service, Immunology and Disease Resistance Laboratory, United States Department of Agriculture
Eric P. Hoberg, Agricultural Research Service, Immunology and Disease Resistance Laboratory, United States Department of AgricultureFollow
Frank Stringfellow, Agricultural Research Service, Immunology and Disease Resistance Laboratory, United States Department of Agriculture
J. Ralph Lichtenfels, Animal Parasitic Disease Lab, ARS, United States Department of AgricultureFollow

Date of this Version

1998

Comments

Published in the Journal of Parasitology (1998) 84(4): 806-812.

Abstract

The first internal transcribed spacer DNA (ITS-1) (rDNA) and the mitochondrial (mt) DNA-derived cytochrome oxidase I gene (COX-1) were enzymatically amplified, cloned and sequenced from 6 nominal species of Ostertagiinae as well as Haemonchus contortus and Haemonchus placei. The portion of the COX-1 gene analyzed was 393 base pairs (bp) in length and contained 33 within species polymorphic base changes at 28 synonymous sites. The ITS-1 rDNA consensus sequences ranged from 392 bp (Ostertagia ostertagi/Ostertagia lyrata, Teladorsagia circumcincta) to 404 bp (H. contortus, H. placei). These data were used both in a distance analysis to assess the concept of polymorphic species within the genus Ostertagia and in parsimony analysis to assess phylogenetic relationships within a limited group of Ostertagiinae. Pairwise similarity scores of both ITS-1 and COX-1 data showed the highest number of conserved sites between the proposed dimorphic species of Ostertagia. The level of similarity was lower in the COX-1 data due to the high number of synonymous base changes. Analysis by maximum parsimony of the same data did not refute O. ostertagiO. lyrata and Ostertagia mossi/Ostertagia dikmansi as dimorphic species and supported monophyly of these ostertagiines relative to representatives of the haemonchine outgroup. In the single most parsi- monious tree from ITS-1 rDNA data, a subclade of Ostertagia spp. included forms possessing parallel synlophes and long esophageal valves that typically occur in cervid hosts.