The First Record of Mass Triploidy in Hybridogenic Green Frog Rana esculenta in Russia (Rostov Oblast')

Abstract

Two green frog species, Rana ridibunda and hybridogenic R. esculenta, were found in Rostov Oblast', south-western Russia. The latter one was recorded in this region of Russia at the first time, providing the south-eastern range limit. Using DNA flow cytometry, we found high incidence of triploidy (96%, LLR kind) among hybrids. This is the first record of mass triploidy for R. esculenta in Rostov Oblast' in particular, and the country in general. Starting in Kharkov Province in eastern Ukraine, the distribution of triploids down Severskii Donets River covers a distance above 480 km and demonstrates two parallel trends. First, the occurrence of triploidy increases in comparison with diploid R. esculenta. Second, the incidence of the LLR triploids seems to increase, while the RRL triploid portion declines. In Rostov Oblast' triploid LLR hybrids co-existed with Rana ridibunda.