Genetic diversity in mitochondrial 12S rDNA of western Palearctic water frogs (Anura, Ranidae) and implications for their systematics

The nucleotide sequence of a part of the mitochondrial 12S rRNA gene of eight western Palearctic water frog species was analysed. The results are consistent with the species status of Rana bedriagae, Rana bergeri, Rana epeirotica, Rana lessonae, Rana perezi, Rana ridibunda, Rana saharica and Rana shqiperica. The obtained DNA data suggest that lake frogs from Greece and Yugoslavia on the one hand and lake frogs from Georgia, Uzbekistan and Turkmenistan on the other hand represent two distinct species. However, it is not yet clear whether lake frogs from Georgia, Uzbekistan and Turkmenistan belong to R. ridibunda or represent a new species. The very high similarity between the analysed 12S rDNA segments of German R. ridibunda and R. lessonae confirm the finding that mtDNA of R. lessonae was transmitted into the mitochondrial gene pool of R. ridibunda probably as a result of backcrosses with the hybridogenetic hybrid R. kl. esculenta. The results of parsimony analyses speak in favour of very close phylogenetic relations between R. perezi and R. saharica; with a high probability these species represent an adelphotaxon. Furthermore, the clades (R. lessonae + R. shqiperica + R. bergeri) and (R. ridibunda + R. bedriagae) are considered to be sister groups. According to the mt 12S rDNA data R. epeirotica seems to be more closely related to the supraspecific taxon (R. ridibunda + R. bedriagae) than to (R. lessonae + R. shqiperica + R. bergeri). Thus, it can be excluded that R. shqiperica and R. epeirotica represent sister species.