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Speciation is not always accompanied by morphological changes; numerous cryptic closely related species were revealed using genetic methods. In natural populations of Ellobius tancrei (2n = 54–30) and E. alaicus (2n = 52–48) of the Pamir-Alay and Tien Shan, the chromosomal variability due to Robertsonian translocations has been revealed. Here, by comprehensive genetic analysis (karyological analyses as well as sequencing of mitochondrial genes, cytb and COI, and nuclear genes, XIST and IRBP) of E. alaicus and E. tancrei samples from the Inner Tien Shan, the Alay Valley, and the Pamir-Alay, we demonstrated fast and independent diversification of these species. We described an incompletely consistent polymorphism of the mitochondrial and nuclear markers, which arose presumably because of habitat fragmentation in the highlands, rapid karyotype changes, and hybridization of different intraspecific varieties and species. The most intriguing results are a low level of genetic distances calculated from mitochondrial and nuclear genes between some phylogenetic lines of E. tancrei and E. alaicus, as well significant species-specific chromosome variability in both species. The chromosomal rearrangements are what most clearly define species specificity and provide further diversification. The "mosaicism" and inconsistency in polymorphism patterns are evidence of rapid speciation in these mammals. [ABSTRACT FROM AUTHOR]

Restricted mobility, sociality, and high inbreeding—characteristic for subterranean mammals—lead to rapid changes in their genome structure. Up to now, the Alay mole vole Ellobius alaicus was a data-deficient species; its spatial and phylogenetic relationships with a sibling species, E. tancrei, were not clarified. We carried out a genetic analysis including differential G-banding of chromosomes and mitochondrial (cytb) and nuclear gene (XIST and IRBP) sequencing. The phylogenetic reconstruction based on cytb represented the expected phylogenetic relationships of two species. Using the XIST, we revealed two new lineages among E. alaicus from the Alay Valley (Southern Kyrgyzstan). Analysis of IRBP demonstrated presence of the specific genotype in most of E. alaicus specimens, but also revealed the haplotype, typical for E. tancrei, in some Alay mole voles. The results may be explained as persistence of ancestral gene polymorphism in E. alaicus or limited interspecific hybridization with E. tancrei. Several chromosomal forms were revealed in E. alaicus in the Alay Valley. We propose that 'mosaic' genetic polymorphism might appear in E. alaicus due to fragmentation of their habitats in highlands of the Alay Valley, Tien Shan, and Pamir-Alay as well as due to hybridization with E. tancrei or persistence of ancestral polymorphisms. [ABSTRACT FROM AUTHOR]

Evolutionary history and taxonomic position for cryptic species may be clarified by using molecular and cytogenetic methods. The subterranean rodent, the Alay mole vole Ellobius alaicus Vorontsov et al., 1969 is one of three sibling species constituting the subgenus Ellobius Fischer, 1814, all of which lost the Y chromosome and obtained isomorphic XX sex chromosomes in both males and females. E. alaicus is evaluated by IUCN as a data deficient species because their distribution, biology, and genetics are almost unknown. We revealed specific karyotypic variability (2n = 52-48) in E. alaicus due to different Robertsonian translocations (Rbs). Two variants of hybrids (2n = 53, different Rbs) with E. tancrei Blasius, 1884 were found at the Northern slopes of the Alay Ridge and in the Naryn district, Kyrgyzstan. We described the sudden change in chromosome numbers from 2n = 50 to 48 and specific karyotype structure for mole voles, which inhabit the entrance to the Alay Valley (Tajikistan), and revealed their affiliation as E. alaicus by cytochrome b and fragments of nuclear XIST and Rspo1 genes sequencing. To date, it is possible to expand the range of E. alaicus from the Alay Valley (South Kyrgyzstan) up to the Ferghana Ridge and the Naryn Basin, Tien Shan at the north-east and to the Pamir-Alay Mountains (Tajikistan) at the west. The closeness of E. tancrei and E. alaicus is supported, whereas specific chromosome and molecular changes, as well as geographic distribution, verified the species status for E. alaicus. The case of Ellobius species accented an unevenness in rates of chromosome and nucleotide changes along with morphological similarity, which is emblematic for cryptic species. [ABSTRACT FROM AUTHOR]