Genetic variability and differentiation of natural populations in three Japanese lung flukes, Paragonimus ohirai, Paragonimus iloktsuenensis and Paragonimus sadoensis (Digenea: Troglotrematidae).

The genetic differences among 3 closely related species, Paragonimus ohirai, Paragonimus iloktsuenensis and Paragonimus sadoensis, were assessed by electrophoretic analysis of allozymes. Fifteen enzymes were analyzed using starch gel electrophoresis. Seven of 18 loci were polymorphic. The most variable population (POs) was polymorphic at 6 of the loci (P = 0.333) with a heterozygosity H of 0.054. Genetic distances between P. ohirai and P. iloktsuenensis, between P. ohirai and P. sadoensis, and between P. iloktsuenensis and P. sadoensis were, on the average, 0.0375, 0.0809 and 0.0567, respectively; values which are well within the usual range for conspecific populations. An especially low estimate of genetic distance was obtained between sympatric populations of P. ohirai and P. iloktsuenensis (0.00059) in Sendai, indicating that gene flow occurred between the 2 species.