Patterns of genetic heterogeneity in Neutraclinostomum intermedialis (Digenea: Clinostomatidae): geographical and temporal considerations
Approximately 300 individuals of Neutraclinostomum intermedialis from three localities in the Northern Province of South Africa were screened using allozyme electrophoresis. The aim was to determine genetic diversity and divergence within and between populations. The within population heterozygosity values (H = 0.5–3.0 %) were generally higher than the value of 0.7%previously estimated for this species from a single population. The mean FST value of 0.69 indicated marked structuring among the populations studied. Genetic distances (Nei 1972) between populations ranged from 0–0.09 and the clustering of populations closely reflected their geographical distribution and linkage to specific river systems. One locus of malate dehydrogenase, E.C.22.214.171.124 (MDH-2), provided a fixed allelic difference between populations from two river systems (the Limpopo and Olifants river systems). We discuss patterns of geographical genetic diversity in N. intermedialis, with reference to the constraints of habitat and host specificity.
Key words: Platyhelminthes, parasite, allozyme electrophoresis, geographical genetic variability.