The Reasons for Extinction of Unisexual Populations of Prussian Carp Carassius gibelio in Water Bodies of Ukraine

Monitoring of the genetic structure of the crucian carp <i>Carassius</i> settlements in the control water bodies over time, as well as experimental crossbreeding of species and biotypes of crucian carps made it possible to determine the main reasons for extinction of the unisexual populations of <i>Carassius gibelio </i>in the water bodies of Ukraine. The mechanisms of gynogenesis were thoroughly investigated, and experiments on the genome incorporation over gynogenesis were carried out. Special attention was paid to the study of deviations from the classic clonal reproduction and the hybrid posterity forming. The histological studies were carried out of the breeders' gonads in view of hermaphroditism and a series of experiments to confirm or refute the presence of the hermaphroditic individuals in populations. Conclusions were drawn regarding the probable autonomous existence of unisexual polyploid populations of crucian carp.