Viable androgenetic YY genotypes of common carp (Cyprinus carpio L.)

To elucidate the genetics of sex determination in common carp (Cyprinus car pio), we attempted to produce homozygous YY individuals using androgenetic reproduction techniques. XY sperm donors were selected from a congenic stra in with stable 50:50 sex ratios, produced by repeatedly backcrossing male o ffspring to a female from a homozygous clone. The YY nature of androgenetic males was tested after crossing with females from different genetic backgr ounds. One androgenetic male sired all male offspring, indicating viability of the YY genotype in common carp, Androgenetic reproduction of the same m ale yielded an all male clone. Viability of the YY genotype in common carp is discussed from an evolutionary background.