Intraspecific genetic differentiation of Siberian newt (Salamandrella keyserlingii, Amphibia, Caudata) and cryptic species S. schrenckii from the Russian South-East

Variability of mitochondrial DNA cytochrome b nucleotide sequences was analyzed in populations of Siberian newt Salamandrella keyserlingii Dybowski 1870 from Ural and Magadan regions, Chukotka, Sakhalin Island, and Primorye. It is shown that in all the populations studied, except for the Primorye one, the low level of geographic variability of morphological features corresponds to the low level of genetic variation, accounting for 0.38% in the combined sample of Magadan, Sakhalin, Chukotka, and Ural animals. Different scenarios for the origin of the genetically and morphologically homogeneous hyperpopulation are discussed taking into account the obvious lack of a gene flow between marginal populations. These scenarios are as follows: the rapid formation of its range in the Holocene; its gradual development in the Pleistocene; the unidirectional (within the whole area) balancing selection; maintenance of the same level of variability due to the mixing of the population during dispersal of young animals and, probably, due to a group fertilization. Despite the small differences between the Primorye and other regional groups of newts, the high level of mtDNA divergence (9.8-11.6%) and the considerable level of intrapopulation variability (1.86%) were revealed in Primorye. The data obtained allow us to recover the name of S. schrenckii (Strauch, 1870) for the newt from Primorye. This name was considered as a junior synonym of S. keyserlingii. Based on the data on the mtDNA variability, the age of S. keyserlingii was estimated at 0.49 MY and that of S. schrenckii, at 2.4 MY. The date of their split was determined as 14 MYA.