Cite this article as:

Faizulin A. I., Svinin A. O., Ruchin A. B., Skorinov D. V., Borkin L. J., Rosanov Y. M., Kuzovenko A. E., Litvinchuk S. N. DISTRIBUTION AND CONTACT ZONE OF TWO FORMS OF THE GREEN TOAD FROM THE BUFOTES VIRIDIS COMPLEX (ANURA, AMPHIBIA), DIFFERING IN GENOME SIZE, IN THE VOLGA REGION. Current Studies in Herpetology, 2018, vol. 18, iss. 1, pp. 35-45. DOI:

This is an open access article distributed under the terms of Creative Commons Attribution 4.0 International License (CC-BY 4.0).



In the Volga region and adjacent territories, 263 specimens of green toads from 63 localities were studied. Genome size analysis by means of flow DNA cytometry allowed the specimens from 16 localities to be identified as the “western” (= viridis) form and the green toads from 20 localities as the “eastern” form (= variabilis or sitibundus). In the other localities studied, specimens with an intermediate genome size predominated. The western form was usually observed to the west of the Volga and Kama rivers, whilst the eastern form was distributed to the east of these rivers. Specimens with an intermediate nuclear DNA content were common in the Volga river floodplain and the basins of some of its tributaries. The presence of such toads gives evidence of gene exchange between both the forms. The contact zone passes through Republic of Kalmykia, the Astrakhan, Volgograd, Saratov and Samara regions, as well as across Republic of Tatarstan. Its total length is above 1,230 km. The width changes along the Volga river from the nar-rower one in the Middle Volga region to the wider one in the Volga river delta. The minimum geographical distance between the populations related to the western form and the eastern form is about 60 km. In the whole, the contact zone can be classified as a narrow hybrid zone, which is quite typical for closely related parapatric species with incomplete reproductive isolation. The evolutionary status of both the forms of green toads is discussed.


Borkin L. J., Litvinchuk S. N. Animal Hybridization, Speciation and Systematics. Proc. of the Zoological Institute RAS, 2013, vol. 317, suppl. 2, pp. 83–139 (in Russian).
Borkin L. J., Litvinchuk S. N., Milto K. D., Rosanov J. M., Khalturin M. D. Cryptic Speciation in Pelobates fuscus (Amphibia, Pelobatidae): Cytometric and Biochemical Evidence. Doklady Biological Sciences, 2001, vol. 376, pp. 86–88.
Borkin L. J., Litvinchuk S. N., Rosanov J. M., Skorinov D. V. On Cryptic Species (from the example of Amphibians). Zoologicheskii zhurnal, 2004, vol. 83, iss. 8, pp. 936–960 (in Russian).
Brylev V. A. Ancient and modern river valleys in the European Southeast of Russia. Erosion and Channel Processes. Moscow, Lomonosov Moscow State University Press, 2000, iss. 3, pp. 123–137 (in Russian).
Ermakov O. A., Fayzulin A. I., Zaks M. M., Kaybeleva E. I., Zaripova F. F. Distribution «western» and «eastern» forms of marsh frog Pelophylax ridibundus s. l. in the Samara and Saratov region (on data of analysis of mtDNA and nDNA). Proc. of the Samara Scientific Center of the Russian Academy of Sciences, 2014, vol. 16, no. 5-1, pp. 409–412 (in Russian).
Litvinchuk S. N., Borkin L. J. Evolution, Systematics and Distribution of Crested Newts (Triturus cristatus complex) in Russia and adjacent Countries. St. Petersburg, Evropeisky Dom Press, 2009. 592 p. (in Rus-sian).
Litvinchuk S. N., Rosanov Yu. M., Usmanova N. M., Borkin L. Ja., Mazanaeva L. F., Kazakov V. I. Variation of microsatellites BM224 and BCAL7 in populations of green toads (Bufo viridis complex) with various nuclear dna content and ploidy. Tsitologiya, 2006, vol. 48, no. 4, pp. 306–319 (in Russian).
Litvinchuk S. N., Rosanov J. M. , Borkin L. J., Skorinov D. V. Molecular, Biochemical and Cytogenetic Aspects of Microevolution in Anurans of Russia and Adjacent Countries. Proc. of the 3th Meeting of the Nikolsky Herpetological SocietyThe Problems of Herpetology”. Saint Petersburg, 2008, pp. 247–257 (in Russian).
Rosanov Yu. M., Vinogradov A. E. Precise DNA cytometry: investigation of individual variability in animal genome size. Tsitologiya, 1998, vol, 40, no. 8–9, pp. 792–799 (in Russian).
Svinin A. O., Ivanov A. Yu., Zaks M. M., Litvinchuk S. N., Borkin L. J., Rosanov J. M., Ermakov O. A. Distribution of the «eastern» and «western» forms of the marsh frog, Pelophylax ridibundus, and their par-ticipation in the origin of hemiclonal hybrids, P. esculentus in Mari El Republic. Current Studies in Herpetology, 2015, vol. 15, iss. 3–4, pp. 120–129 (in Russian).
Skorinov D. V., Litvinchuk S. N., Borkin L. J., Rosanov J. M. Genetic differentiation, genome size and morphological variation in newts of the Lissotriton vulgaris group. Proc. of the 3th Meeting of the Nikolsky Herpetological SocietyThe Problems of Herpetology”. Saint Petersburg, 2008, pp. 375–383 (in Russian).
Khalturin M. D., Rosanov J. M., Litvinchuk S. N., Borkin L. J. Comparison of methods for identification of hybrid genomes in zones of interspecific contacts. Tsitologiya, 2000, vol, 42, no. 3, pp. 314–315 (in Russian).
Khalturin M. D., Rozanov Yu. M., Litvinchuk S. N., Borkin L. J. Hybridization between the eire-bellied toads Bombina bombina and B. variegata in the Ukrainian Transcarpathians. Proc. of the 1th Meeting of the Nikolsky Herpetological SocietyThe Problems of Herpetology”. Pushino, Moscow, Moscow Lomonosov State Uni-versity Press, 2001, pp. 312–313 (in Russian).
Khalturin M. D., Litvinchuk S. N., Borkin L. J., Rozanov Yu. M., Milto K. D. Genetic variation in two cryptic forms of the common spadefoot toad Pelobates fuscus (Pelobatidae, Anura, Amphibia) differing in ge-nome size. Tsitologiya, 2003, vol, 45, no. 3, pp. 308–323 (in Russian).
Yanchukov A. W., Mezhzherin S. V., Morozov-Leonov S. Yu. Analysis of the Hybrid Zone between Fire-Bellied (Bombina bombina) and Yellow-Bellied (Bombina variegata) Toads in Pre-Carpathian. Vestnik Zoologii, 2002, vol. 36, no. 4, pp. 41–46 (in Russian).
Arnold M. L. Evolution through Genetic Exchange. Oxford, Oxford University Press, 2006. XIV+ 252 p.
Borkin L. J., Caune I. A., Pisanetz E. M., Rozanov Y. M. Karyotype and genome size in the Bufo viridis group. In: Z. Roček, ed. Studies in Herpetology. Prague, Charles Univ. Press, 1986, pp. 137–142.
Borkin L. J., Litvinchuk S. N., Rosanov J. M., Milto K. D. Cryptic speciation in Pelobates fuscus (Anura, Pelobatidae): evidence from DNA flow cytome-try. Amphibia–Reptilia, 2001, vol. 22, no. 4, pp. 387–396.
Borkin L. J., Litvinchuk S. N., Rosanov J. M., Khalturin M. D., Lada G. A., Borissovsky A. G., Faizulin A. I., Kotserzhinskaya I. M., Novitsky R. V., Ruchin A. B. New data on the Distribution of two Cryptic forms of the Common Spadefoot Toad (Pelobates fuscus) in Eastern Europe. Russ. J. of Herpetology, 2003, vol. 10, no. 2, pp. 111–118.
Borkin L. J., Litvinchuk S. N., Rosanov J. M., Džukić G., Kalezić M. L. Genome size variation in the Balkan anurans. In: N. Ananjeva, O. Tsinenko, eds. Herpetologia Petropolitana: Proc. of the 12th Ordinary Gen-eral Meeting of the Societas Europaea Herpetologica. Saint Petersburg, 2005, pp. 16–19.
Dubois A., Bour R. The nomenclatural sta-tus of the nomina of amphibians and reptiles created by Garsault (1764), with a parsimonious solution to an old no-menclatural problem regarding the genus Bufo (Am-phibia, Anura), comments on the taxonomy of this genus, and comments on some nomina created by Laurenti (1768). Zootaxa, 2010, no. 2447, pp. 1–52.
Dufresnes C., Bonato L., Novarini N., Betto-Colliard C., Perrin N., Stöck M. Inferring the Degree of Incipient Speciation in Secondary Contact Zones of Closely Related Lineages of Palearctic Green Toads (Bufo viridis subgroup). Heredity, 2014, vol. 113, no. 1, pp. 9–20.
Frost D. R., Grant T., Faivovich J., Bain R. H., Haas A., Haddad C. F. B., De Sa R. O., Channing A., Wilkinson M., Donnellan S. C., Raxworthy C. J., Campbell J. A., Blotto B. L., Moler P., Drewes R. C., Nuss-baum R. A., Lynch J. D., Green D. M., Wheeler W. C. The Amphibian Tree of Life. Bull. of the American Museum of Natural History, 2006, no. 297, pp. 1–370.
Inger R. F. Bufo of Eurasia. In: W. F. Blair, ed. Evolution in the genus Bufo. Austin, London, University of Texas Press, 1972, pp. 102–118.
Litvinchuk S. N., Borkin L. J., Rosanov J. M., Skorinov D. V. Allozyme and genome size variation in tree frogs from the Caucasus, with description of a new subspecies Hyla arborea gumilevskii, from the Talysh Mountains. Russ. J. of Herpetology, 2006, vol. 13, no. 3, pp. 187–206.
Litvinchuk S. N., Borkin L. J., Skorinov D. V., Rosanov J. M. A new species of common toads from the Talysh Mountains, south-eastern Caucasus: genome size, allozyme, and morphological evidence. Russ. J. of Herpetology, 2008 a, vol. 15, no. 1, pp. 19–43.
Litvinchuk S. N., Borkin L. J., Rosanov J. M. Genome size variation in Rana arvalis and some related brown frog species, including taxonomic comments on the validity of the R. arvalis subspecies. Zeitschrift für Feldherpetologie, 2008 b, Suppl. 13, pp. 95–112. 
Litvinchuk S. N., Crottini A., Federici S., De Pous P., Donaire D., Andreone F., Kalezić M. L., Džukić G., Lada G. A., Borkin L. J., Rosanov J. M. Phylogeographic patterns of genetic diversity in the common spadefoot toad, Pelobates fuscus (Anura: Pelobatidae), reveals evolutionary history, postglacial range expansion and secondary contact. Organisms Diversity and Evolution, 2013, vol. 13, iss. 3, pp. 433–451.
Özdemir N., Kultrup B. Intraspecific variation of Turkish green toads, Bufo (Pseudepidalea) viridis Laurenti, 1768, based on 16S ribosomal RNA sequences (Anura: Bufonidae). Herpetozoa, 2007, vol. 20, no. 1–2, pp. 3–10.
Özdemir N., Gül S., Poyarkov N. A., Kutrup B., Tosunoğlu M., Doglio S. Molecular systematics and phylogeography of Bufotes variabilis (syn. Pseudepidalea variabilis Pallas, 1769) in Turkey. Turkish J. of Zoology, 2014, vol. 38, no. 4, pp. 412–420. 
Stöck M., Moritz C., Hickerson M., Frynta D., Dujsbayeva T., Eremchenko V., Macey J. R., Papenfuss T. J., Wake D. B. Evolution of mitochondrial relationships and biogeography of Palearctic green toads (Bufo viridis sub-group) with insights in their genome plasticity. Molecular Phylogenetics and Evolution, 2006, vol. 41, iss. 2, pp. 663–689. 

Stöck M., Roth P., Podloucky R., Grossenbacher K. Wechselkröten unter Berücksichtigung von Bufo viridis virdis Laurenti, 1768; Bufo variabilis (Pallas, 1769); Bufo boulengeri Lataste, 1879; Bufo balearicus Böttger, 1880 und Bufo siculus Stöck, Sicilia, Belfiore, Lo Brutto, Lo Valvo und Arculeo. Handbuch der Reptilien und Amphibien Europas. Bd. 5 (Froschlurche II). Wiebelsheim, Aula Verlag, 2008, S. 413–498.

Szymura J. M. Analysis of hybrid zones with Bombina. In: R. Harrison, ed. Hybrid Zones and the Evolutionary Process. New York, Oxford University Press, 1993, pp. 261–289.
Szymura J. M., Uzzell T., Spolsky C. Mitochon-drial DNA variation in the hybridizing fire-bellied toads, Bombina bombina and B. variegata. Molecular Ecology, 2000, vol. 9, iss. 7, pp. 891–899.
Yanchukov A., Hofman S., Szymura J. M., Mezhzherin S. V., Morozov-Leonov S. Y., Barton N. H., Nürnberger B. Hybridization of Bombina bombina and B. variegata (Anura, Discoglossidae) at a sharp ecotone in western Ukraine: comparisons across transects and over time. Evolution, 2006, vol. 60, no. 3, pp. 583–600.

Short text (in English): 
Full text (in Russian): 
Номер страницы (по):