Publication details

The consequences of hybridization on metazoan parasite infection level in cyprinids

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Year of publication 2018
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description The hybrids are considered as a bridge-gap between parental species allowing parasite transfer from one host species to another. It was hypothesized that interruption of species-specific host-parasite co-adaptation may result in differences in the parasite load between parental species and their hybrids. In addition, it was also proposed that the maternal ancestry of the hybrids may contribute to the differences in parasite load between different hybrid lines. The main aim of this study was to investigate differences in parasite infection, and immune and physiological parameters between parental species and F1 hybrids using the selected cyprinid systems exhibiting hybridization. Additionally, we analyzed the effect of maternal origin of hybrids on parasite infection. Parasite infection level was examined in two cyprinid systems exhibiting hybridization. The first system represented the natural hybridization between two phylogenetically distant species, roach (Rutilus rutilus) and common bream (Abramis brama). All specimens were identified using morphological characteristics and genetic markers (partial mitochondrial cyt b gene and 12 microsatellite loci). The second system was represented by an artificially prepared lines of pure species and F1 hybrids using two phylogenetically closely related species, silver bream (Blicca bjoerkna) and common bream (A. brama). Monogeneans were dominant in the parasite communities of both pure species and their hybrids. In both systems, F1 hybrids displayed higher parasite species richness than their respective parental species, with both specialist and generalist parasites of the pure species present in the parasite communities of hybrids. However, some species-specific parasite species were not present in hybrids. On the other hand, parasite abundance was higher in parental species compared to the hybrids. We observed asymmetry in the distribution of specific parasites in hybrids in favour of the specific parasites of one parental species in both systems studied. In the system of phylogenetically distant cyprinid species, we detected a significant effect of maternal origin on the digenean and crustacean infection of hybrids. The significant effects of season, sampling site and year of collection on the composition of the metazoan parasite communities were found. In the system of phylogenetically distant cyprinid species, similarities in spleen-somatic index between hybrids and roach and in hepato-somatic index between hybrids and common bream were detected, nevertheless, gonado-somatic index in hybrids was intermediate between parental species. The non-specific immunity was affected only by season. The effects of the fish group (considering roach, common bream and hybrids) and sex on the fish condition were found. Our findings concerning the distribution of parental species-specific parasites in hybrids suggest that different host specific parasites display the different degrees of host-parasite co-adaptation. Our study showed that the hybrid’s protective immunological mechanism is more closely resemble that of one of the parental species.
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