Signatures of genetic isolation of the three lineages of the narrow-headed vole Lasiopodomys gregalis (Cricetidae, Rodentia) in a mosaic steppe landscape of South Siberia

Abstract

Geographic isolation is among the most important factors initiating speciation in mammals. The narrow-headed vole Lasiopodomys gregalis is a widely distributed species in steppe habitats of South Siberia that are highly fragmented by mountain ranges. There are three major mostly allopatric mitochondrial lineages of L. gregalis described throughout the distribution range that most plausibly split in the Middle Pleistocene. This study applies the analysis of five microsatellite loci and species distribution modelling to understand the patterns of isolation and migration between L. gregalis populations in South Siberia and in particular in Tuva basin where all three lineages occur simultaneously. Microsatellite analysis supported the population differentiation revealed previously, with three clusters corresponding to mitochondrial lineages and indicated that gene flow between them is strongly limited. There were only traces of hybridisation in the population near the contact zone of lineages B and C. SDM analysis predicted only a small number of potential contact zones between L. gregalis lineages and barriers corresponding to landscape heterogeneity. We presume that the forested mountain ranges act as the main insurmountable barriers to gene flow between major genetic lineages of L. gregalis.

Narrow-Headed Voles Species Complex (Cricetidae, Rodentia): Evidence for Species Differentiation Inferred from Transcriptome Data

“…The results of experimental breeding showed the presence of posterity in all combinations of A, B, and C L. gregalis lineages; however, it was shown that not every reciprocal combination had posterity that was numerous and viable [9,10]. Using a microsatellite loci analysis [11] we found traces of hybridisation in the two most phylogenetically close lineages, B and C, which, according to our estimates [7], separated about 250 thousand years ago. Despite the absence of continuous geographical barriers in nature between the lineage distribution ranges, we did not find any traces of hybridization from lineage A with lineages B and C, separation from which probably occurred about 400 thousand years ago.…”

“…were well isolated from each other genetically (gene flow between them was strongly limited and traces of hybridisation were found in only the contact zone of lineages B and C). A species distribution modeling analysis predicted the presence of barriers between the lineages that correspond to landscape heterogeneity and only a small number of potential contact zones [11]. These results suggested that these three genetic lineages of L. gregalis s. str.…”

Supernumerary chromosomes contribute to karyotypic diversity within cryptic species of the subgenus Stenocranius (Cricetidae, Rodentia): comparative analyses of chromosomes and synaptonemal complexes

“…1, sampling site 4). It is di cult to guess the reasons for this nding, but it is curious that an individual with Bs was collected in the area of the probable separation of the three genetic lineages A, B and C. Perhaps an analysis of representatives of lineage A from the eastern part of the Tuva Basin and Southern slopes of the Western Tannu-Ola Range (Petrova et al, 2021) will resolve this question.…”

“…1). Despite the presence of several potential contact zones in the Altai-Sayan Region, lineages A, B and C were reported to be well isolated from each other genetically, which allows us to recognise them as separate taxa (Petrova et al, 2021). The mechanisms of their isolation are not yet clear, because experimental breeding did not reveal clear signs of reproductive isolation between them (Petrova et al, 2016).…”

“…In the current study, to identify speciation mechanisms within the narrow-headed vole cryptic species complex, we analyse karyotypic variation of Stenocranius voles from previously unexplored regions of South Siberia and, in particular, from the Altai-Sayan region, which has probably been the centre of L. gregalis diversity based on results of both modern-DNA (Petrova et al, 2021) and ancient-DNA analyses (Baca et al, 2023), as well as from the Transbaikal Region: the probable area of Early Pleistocene separation within the subgenus Stenocranius. In addition, using immunocytochemical analysis of synaptonemal complexes (SCs) in Stenocranius pachytene spermatocytes, we examine the structure and meiotic silencing of Bs.…”