Biochemical differentiation in bile duct cestodes and their marsupial hosts

Isozyme electrophoresis was used to assess possible cospeciation ofparasites (cestodes of the Progamotaenia festiva complex) and their hosts(Australian diprotodont marsupials) and to compare the extent ofinterspecific genetic diversity of the parasites and their hosts. On thebasis of morphology, there are three species in the complex, althoughelectrophoresis revealed 14 distinct genetic types, most of which were hostspecific, although there were three cases of apparent host switching. Theevolutionary relationships among the parasites were only partiallyconcordant with those among the hosts. Moreover, the extent ofelectrophoretic diversity among the parasites was much higher than thatamong hosts.