Population structure of Kapentagyrus spp. infecting clupeid host species in Lake Tanganyika
Fisheries in Lake Tanganyika, the oldest African Great Lake, is mostly dependent on a migrating fish stock of two endemic species of sardines, Limnothrissa miodon and Stolothrissa tanganicae. They are parasitized by two species of Kapentagyrus (Monogenea, Dactylogyridae), Kapentagyrus limnotrissae and Kapentagyrus tanganicanus. Even though studies in order to describe clupeids’ lake-wide population structure have been made, no clear pattern has been determined so far. Considering the potential magnifying glass effect, we investigated population structure of Kapentagyrus spp. as indirect tags for clupeids’ stock identification via combined morphological and molecular approach. Secondly, as evolution and demographic history of various cichlid species in the lake was reported to relate to the historical lake level changes, we investigated the effect of such events on past population changes of Kapentagyrus spp. living in so far understudied lake’s pelagic zone. Intraspecific morphological variation of the monogeneans was analysed using morphometrics and geomorphometrics of sclerotised structures. Genetic population structure was assessed based on a 415 bp fragment of the mitochondrial COI gene. Although significant differences in some of the morphological parameters potentially indicate limited parasite migration, no clear geographically dependent structure was identified. High proportion of one central haplotype in both species of Kapentagyrus supports rather unlimited gene flow in a lake-wide scale. We hence suggest an overall lack of clear geographic structure, which corresponds with the results reported for both host species in previous studies. However, significant genetic differentiation between some of the sampling sites connotes restricted genetic exchange in different than a purely geographical scale.