[RAPD fingerprinting of common bream Abramis brama L., roach Rutilus rutilus L., and their F1 hybrids]

The polymerase chain reaction with arbitrary primers (RAPD-PCR) was used to study and to evaluate the genetic variation in the hybrid progeny of two Cyprinidae species, common bream Abramis brama and roach Rutilus rutilus. Genetic polymorphism was studied in 20 fishes (young of the current year) obtained in four individual crosses: R. rutilus x R. rutilus (RR), A. brama x A. brama (AA), R. rutilus x A. brama (RA), and A. brama x R. rutilus (AR). Amplification spectra obtained with eight primers contained 288 fragments, 97.6% of which proved to be polymorphic. The proportion of polymorphic fragments was 75.0% in the RR progeny, 58.1% in the AA progeny, 84.9% in the AR progeny, and 77.8% in the RA progeny. Classification analysis in the space of principal components was performed with the first four components, which together accounted for 64% of the total variance of the character under study. The individual contributions of components I, II, III, and IV were 26.8, 16.8, 11.5, and 8.9%, respectively. Fishes of the two pure species and the hybrid progeny (direct and reverse hybrids together) were clearly differentiated in the space of principal components I and II. The best differentiation of the four samples (RR, AA, RA, and AR) was observed in the space of principal components II and IV. Possible causes of high genetic variation in interspecific hybrids are discussed.