Reproduction and the Evolutionary Potential of the Hybrid Form Pelophylax Esculentus-Bidibundus (Amphibia, Ranidae) within the Drainages of Pripyat, Dniester, and Southern Bug Rivers

The genetic diversity of the marsh frog Pelophylax ridibundus populations and the hemiclonal structure of the hybrid form Pelophylax esculentus-ridibundus within the drainages of Prypyat, Dniester, and Southern Bug rivers were analyzed. The absence of a single evolutionary scenario for this hybrid form within the borders of the region has been revealed. The conservation of the basic level of parental species’ evolutionary potential and the interpopulation differentiation of the hybrid form within the drainages of Dniester and Southern Bug rivers was demonstrated. At the same time, in the populations of P. esculentus-ridibundus from the Prypyat basin, a loss of evolutionary potential was revealed (by 31% in the southern part, by 69% in the northern part). It was revealed that the reason for this was the tendency to the extinction of rare haplotypes and the expansion of the mass ones. It was also demonstrated that there was a significant increase (nine to ten times) in the interpopulation differentiation of the hybrid form from the Prypyat River drainage compared with sympatric populations of the parental species P. ridibundus. It was shown that the evolutionary potential loss of the hybrid form P. esculentus-ridibundus accelerated in the absence of parental species, which confirms the hypothesis about regular hybridization as an effective mechanism to compensate for the loss of evolutionary potential.