Cryptic variation in mole voles Ellobius (Arvicolinae, Rodentia) of Mongolia

Abstract

The mole vole subgenus Ellobius is currently considered to include three species: Ellobius talpinus (distributed from SE Europe and Turkmenistan through Kazakhstan to SW Siberia), Ellobius alaicus (S Tianshan, Pamir‐Alay) and Ellobius tancrei (East and West Central Asia, from the Amu‐Darya to Mongolia and N China). A study focusing on the genetic variation in Ellobius from Mongolia was conducted using one mitochondrial and three nuclear markers. Two divergent allopatric lineages endemic to East Central Asia were revealed. The first lineage occurs from Dzungaria eastwards to central Mongolia and represents E. tancrei sensu stricto. The second lineage is found in East Gobi only and corresponds to a taxon described as Ellobius orientalis, which has been traditionally treated as a subspecies of E. tancrei. However, molecular and chromosome data indicate that orientalis is related not to E. tancrei but to E. talpinus, which is separated from the former by a distribution gap of ~2,000 km. The taxonomic status of the East Gobi mole vole is ambiguous, and its genetic distance from E. talpinus s. str. falls into the range characteristic for closely related vole species or semi‐species. According to molecular estimates, the two taxa have been isolated since the late Middle Pleistocene. A similar divergence is observed between the East and West Central Asian lineages of E. tancrei. E. alaicus is placed as sister to the latter rendering E. tancrei sensu lato paraphyletic. The revealed phylogeographic pattern implies that East Central Asia was colonized by mole voles through multiple eastward dispersal events.

Geographic Mosaic of Extensive Genetic Variations in Subterranean Mole Voles Ellobius alaicus as a Consequence of Habitat Fragmentation and Hybridization

“…The similar results were described earlier, and mole voles from western and central parts of Mongolia were proposed to belong to a new cryptic species; however, these individuals are currently considered as E. tancrei s. str. [ 14 ]. Within the main E. tancrei clade, joining mole voles from the Central Asia, specimens from Uzbekistan (#27) and from the southwestern regions of Tajikistan, remote from the Surkhob and Alay Valleys (#26), appeared to be isolated.…”

“…We assumed that for the reconstruction of the sibling species phylogeny, data on the XIST gene (one of the actively used sex-linked markers) would be valuable [ 14 , 18 , 28 , 39 ]. Indeed, the analysis of the sequences of its two fragments transformed and added details to the above picture.…”

“…Accession numbers were as follows: ON333901–ON333931 for the cytb gene, ON333848–ON333900 for the IRBP gene, ON314941–ON314990 for the XIST gene first fragment, and ON314885–ON314940 for the XIST gene second fragment. We also used some of the earlier published sequences [ 14 , 18 ] deposited by us to the GenBank (MG264318–MG264322, MG264324, MG264326–MG264330, MG264345, MG264346, MK544901, MK544903, MK544904, MK544906–MK544917, and MT468380 for the cytb gene; MT478768–MT478770 for the IRBP gene; and MK544921–MK544926 for the XIST gene first fragment; see the Table S1 ). A total of 60 specimens were used for the mitochondrial cytb gene sequencing, with 56 specimens for the IRBP gene and the XIST gene sequencing.…”

“…No chromosomal variability is known for E. talpinus s. str. (2n = NF = 54) [ 13 , 14 ], while for E. tancrei , high variability (2n = 54–30, NF = 56) was found in the Pamir-Alay [ 15 , 16 ]. Also, several chromosomal forms (2n = 52–48, NF = 56) were revealed in E. alaicus [ 17 , 18 ].…”

High molecular variability in three pine vole species of the subgenus Terricola ( Microtus , Arvicolinae) and plausible source of polymorphism

“…The current study was undertaken to assess M. subterraneus, M. daghestanicus, and M. majori with regard to their genetic variability, precise differentiation level between the species, and their relationships using multiple molecular markers: the entire mitochondrial cytb gene and fragments of the nuclear BRCA1 (breast and ovarian cancer type 1 susceptibility protein) gene, exon 11, the IRBP (interphotoreceptor retinoid-binding protein) gene, exon 1, and the XIST (X-inactive specific transcript) gene. Recently, the sequencing of protein-coding nuclear BRCA1 and IRBP genes has been actively pursued for similar studies of various mammalian groups (e.g., Adkins et al, 2001;Bannikova et al, 2013;Bogdanov, Maltsev, et al, 2020;Lebedev et al, 2018Lebedev et al, , 2020Martínková & Moravec, 2012). The product of the XIST gene, localized on the X chromosome in rodents, is a non-coding RNA, which, in interaction with some proteins, takes part in regulating the inactivation of one X chromosome in females (Nesterova et al, 2001).…”