Parasitology, Harold W. Manter Laboratory of
Date of this Version
1987
Abstract
Vertical starch gel electrophoresis and trefoil immunodiffusion were used to study the systematics of some ascaridoid nematodes. Within the Ascarididae, the time scale of divergence was too great for intergeneric electrophoretic comparisons. Congeneric electrophoretic comparisons of Baylisascaris procyonis (host- raccoon) versus Baylisascaris transfuga (host- Black bear), and Toxocara canis (host- domestic dog) versus Toxocara cati (host- domestic cat) yielded Nei genetic distance coefficients of 1.21 and 1.55, respectively. Estimates of times of divergence made from 1 electrophoretic clock calibration suggest that the Baylisascaris species have not shared a common ancestor for 25 million years (Myr), and that the Toxocara species diverged 33 Myr ago. The Baylisascaris divergence estimate corresponds to host-family divergence estimates based on immunological and paleontological evidence, which suggests that cospeciation has occurred. In contrast to this, Ascaris suum (host- pig) and Ascaris lumbricoides (host- human) have a distance coefficient of 0.09. This indicates that these species diverged comparatively recently and may represent a case of host rance expansion. Trefoil immunodiffusion comparisons of ascaridoid albumins yielded reactions of identity of A. suum, A. lumbricoides, Parascaris equorum, B. procyonis, B. transfuga, T. canis, and T. cati. This confirms that these taxa are members of a monophyletic group
Comments
Published by Nadler in Journal of Parasitology (1987) 73(4). Copyright © American Society of Parasitologists [1987]. Used by Permission.