Publication details

Variability, structure and selection of MHCIIB genes in Chondrostoma toxostoma and Chondrostoma nasus in hybrid zones

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Year of publication 2012
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description To characterise the overall genetic diversity, population structure and selection processes in cyprinid fish, MHC genes of IIB class have been analyzed. As the model organism in this study, two congeneric cyprinids, the introduced Chondrostoma nasus and native, protected and endemic C. toxostoma that live in sympatry and form a hybrid zone in the Durance River (South France, Mediterranean Sea drainage) were studied. For the individual determination (pure species versus hybrid) all fish were genotyped for mtDNA (cyt b) and 41 microsatellite loci. The allelic variability in exon 2 of two MHCIIB genes (DAB1-like and DAB3-like) representing the most variable region with the nonsynonymous sites specifying the peptide binding region was analysed. The results reveal the non uniform allele expression within individuals, duplication of both studied loci (previously showed in several cyprinid species) and that the exon 2 of DAB genes is subjected to positive selection. The difference in the MHCIIB profiles was found between allopatric and sympatric populations. Based on the hypothesis of parasite-mediated selection maintaining MHC polymorphism it could suggest the difference in parasite load between chondrostomes living in allopatric area and those living in hybrid zone.
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