Genetic variation in the triploids of Japanese Fasciola species, and relationships with other species in the genus

Abstract

Twelve enzymes (encoded by 14 loci) in liver flukes of Fasciola species originating from Japan (parthenogenetic triploids), Korea (parthenogenetic diploids), the United States of America (USA) and Australia (all sexual diploids) were analysed using starch gel electrophoresis. Variation in electrophoretic patterns between samples was detected at fic enzyme loci (Ak, Got, Gpi, 6-Pgd and Pgm-2). Japanese worms (31, of which six were established as uniparental laboratory strains), which reproduce by parthenogenesis, exhibited three different isozyme patterns. This indicates that triploidy has arisen more than once in Japanese flukes. Japanese Fasciola sp. can be separated into three types on morphological grounds. For the six laboratory strains of Japanese worms, the parental morphological type was known. Each of the three isozyme patterns observed was restricted to one morphological type. Most alleles detected in the Japanese triploids were also found in diploid worms from the other countries: the only alleles not represented elsewhere were four at the Got locus and two at the Pgm locus. Flukes from a laboratory strain derived from a single Korean diploid worm resembled the Japanese worms in genotype more closely than did America (seven uniparental laboratory strains) or Australian (30 worms) specimens. Worms from the last two countries were closely related.