ISSN 1022-7954, Russian Journal of Genetics, 2008, Vol. 44, No. 8, pp. 948–958. © Pleiades Publishing, Inc., 2008. Original Russian Text © N.A. Poyarkov, S.L. Kuzmin, 2008, published in Genetika, 2008, Vol. 44, No. 8, pp. 1089–1100. 948 INTRODUCTION The Siberian newt Salamandrella keyserlingii belongs to the primitive family Hynobiidae. Among all Palearctic amphibians, S. keyserlingii tridactyla has the greatest species range and is found in the northeastern part of European Russia, Siberia, the northern part of Kazakhstan, Mongolia, China, Korea, and Japan. At the same time, the species is characterized by an extreme morphological uniformity without a distinct geograph- ical variation, which has given grounds for considering the taxa described for this species to be invalid [1, 2]. Differences in ecology have been reported for individ- ual populations from different geographical localities, as well as morphological and ontogenetic modifications [1, 3–6] and a genetic variation [7, 8]. A special status has been proposed for the populations of Primorye [4, 5, 8, 9]. Berman et al. [10, 11] have assumed that the Primorye populations represent a separate species. Analysis of a mitochondrial cytochrome b gene frag- ment has led to the conclusion that molecular differen- tiation between the populations of Primorye and Sibe- ria is high enough to isolate two species: former S. key- serlingii tridactyla [8, 9] has been termed schrenckii (Primorye and southern Khabarovsk krai) and the other populations (almost total range, mostly Siberia) have been termed keyserlingii. Owing to the vast distribution and the irregular geo- graphical variation of molecular markers, Siberian newt provides an appealing model for phylogeographi- cal studies. Moreover, Siberian newt is one of the few amphibian species that efficiently survive in adverse polar environments. The molecular variation of the spe- cies throughout the entire species range has not been studied as of yet, although such studies are necessary for understanding the mechanisms of differentiation of geographical populations and reconstructing the his- tory of the species range formation. We focused on this problem in our work. Since the taxonomy and the spe- cies status of the Siberian newt population from Pri- morye are beyond the scope of this paper, the above two taxa are hereafter designated as Primorye and Siberian forms. MATERIALS AND METHODS Material. Tissue specimens were obtained from newts of mainland and island (Sakhalin, Paramushir, Kunashir, and Hokkaido) populations. In total, we examined 173 newts from 30 mainland and four island populations (table, Fig. 1). The mean sample size was five newts per population, which is usually considered to be sufficient for phylogeographical studies [12, 13]. The maximum sample (ten newts) was from the Kedrovaya Pad’ nature reserve, and the minimum sam- ple (one newt) was from Paramushir (this was caused by the poor quality of the material). In addition to the original data, our analysis included the published sequences of a cytochrome b gene fragment of 86 newts [10, 11] (NCBI GenBank accession nos. AY701904– AY701989, http://www.ncbi.nlm.nih.gov/entrez). The cytochrome b sequence of the closely related Korean salamander Hynobius leechii (family Hynobiidae) was established using an individual from Korea; the Phylogeography of the Siberian Newt Salamandrella keyserlingii by Mitochondrial DNA Sequence Analysis N. A. Poyarkov a and S. L. Kuzmin b a Department of Vertebrate Zoology, Biological Faculty, Moscow State University, Moscow, 119991Russia e-mail: ipe51@yahoo.com b Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, 119071 Russia e-mail: poyarkov@orc.ru Received February 12, 2007; in final form, September 19, 2007 Abstract—Differentiation of geographical populations of the Siberian newt Salamandrella keyserlingii throughout the species range was analyzed using a fragment of the cytochrome b gene. The population of the Primorye region (Russian Far East) is separated to the greatest extent; the Japanese and South Kuril populations are the next most separate. These populations are possibly subspecies. Geographical differentiation of popula- tions in the Siberian part of the species range is lower, lacks a clinal variation, and is irregular. The molecular variation of S. keyserlingii supports the hypothesis that several primary vicarious refugia of pre-Pleistocene dif- ferentiation of a common ancestor of Salamandrella occurred in the southeastern part of its current distribution range and that northern and western regions were gradually colonized via repeated steps of expansion and retreat in the Siberian part of the modern species range. DOI: 10.1134/S1022795408080097 ANIMAL GENETICS