Publication details

The variability of MHC genes and parasite selection in hybrids of common bream (Abramis brama) and roach (Rutilus rutilus)

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Year of publication 2015
Type Appeared in Conference without Proceedings
MU Faculty or unit

Faculty of Science

Description Hybridization is a common phenomenon reported in cyprinid fish. Depending on the extent of evolutionary divergence among hybridizing parental taxa, two hypotheses have been proposed: (1) the hybrids suffer from a breakdown of co-adapted genes (leading to decreasing the efficiency of the defence mechanisms linked to high parasite susceptibility) or (2) hybrids exhibit high vigour due of the heterosis effect which confers advantages to increased genetic diversity (this mechanism explain the success of hybrids). In our study, we focused on the hybridization of two non-congeneric cyprinid fish species – roach (Rutilus rutilus) and common bream (Abramis brama). Both fish species exhibit the different metazoan parasite species, especially host-specific ectoparasitic monogeneans. Hybrids were determined on the basis of morphological traits and using molecular markers (cyt b and several microsatellite loci). The aim of this study was to analyse the variability of major histocompatibility complex genes (MHC) of IIB class (including DAB1 and DAB 3 genes) and metazoan parasite infection in coexisting parental-hybrid system. We predict high parasite intensity and weakened immunity (i.e. impaired system of co-adaptation genes) in hybrids of two divergent species. For DAB1 marker, we identified only the homozygotes for common bream, and the homozygotes were more frequent than heterozygotes for roach and hybrids. For DAB3 marker, the similar proportion of both homozygotes and herozygotes was found for all fish categories. We found that each of the parental species is parasitized by host-specific parasites. Hybrids of both maternal origins were identified; however, the majority of them were of common bream maternal origin. Hybrids harbour high parasite species richness but the parasite abundance was lower in hybrids compared to parental species. Hybrids harbour all specific parasites of roach, but the presence of common bream-specific parasites in hybrids was restricted.
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