Allozyme analysis of genetic variation and polymorphism in Eubothrium salvelini and E. crassum (Cestoda: Pseudophyllidea) from alpine lakes

Abstract

The genetic structure of the most abundant species in the genus Eubothrium, E. crassum and E. salvelini, was studied by allozyme analysis in order to provide a consistent diagnosis for these morphologically similar species, as well as to assess their genetic relatedness. The proportion of fixed allelic differences (56.3%, 9 of 16 loci) between the species falls within the range accepted for valid species. A strict host specificity of E. crassum and E. salvelini for their typical host (lake trout, Arctic charr, respectively) was found in the French localities examined (Lake Annecy, Lake Bourget). For E. salvelini, polymorphism with the established allelic profile was found in the acid phosphatase (ACP) system. No significant deviation from the Hardy-Weinberg equilibrium expectations for ACP were found in either of the E. salvelini populations, which suggests predominantly cross-fertilization of these hermaphrodites. Analysis of the standardized variance in allelic frequencies demonstrated almost no among population differentiation (estimator theta of Fst = -0.03) between E. salvelini populations.

Redescription of Eubothrium fragile (Rudolphi, 1802) and E. rugosum (Batsch, 1786) (Cestoda: Pseudophyllidea), parasites of fish in the Holarctic Region

“…The present data support some of Nybelin's (1922) conclusions and the results of recent studies, based on comparable material of four species of Eubothrium (Hanzelová et al 2002, Scholz et al 2003, Šnábel et al 2004. The measurements of the scolex and its shape may help to distinguish individual Eubothrium species.…”

“…Specimens of this species from marine hosts are markedly larger than those from freshwater hosts (Andersen and Kennedy 1983). Morphological variability, however, is not reflected in the genetic structure of E. crassum (isoenzyme patterns and sequences of the ITS rRNA genes) of freshwater and marine populations (Kráľová et al 2000, 2001, Kráľová-Hromadová et al 2003, Šnábel et al 2004.…”