Scientists from the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences (IEE RAS), co-authored with colleagues from the N.K. Koltsov Institute of Developmental Biology of the Russian Academy of Sciences (IB RAS), presented prioritized data on the multilevel molecular differentiation of the Strand's birch mouse, Sicista strandi, a restricted-range southern European-Caucasian species.
To clarify the nature of Sicista strandi differentiation (the appearance of the specimen from the Kursk region is shown above), the authors analyzed the variability of the mitochondrial cytb gene and a fragment of the first exon of the nuclear IRBP gene in several species samples. The obtained results demonstrated the subdivision of S. strandi into two genetically highly separated forms: one (northern - II) includes individuals from the Belgorod (Belogorye) and Kursk regions, and the other (southern - I - A, B) includes samples from populations of the North Caucasus, Saratov, Rostov (R/D), and Luhansk regions. Within the southern form, moderate differences were detected for the first time between Strand's birch mice from the Rostov region and populations of the North Caucasus and Saratov region. One S. strandi specimen from the Belgorod region was noted to have haplotypes of the IRBP gene typical for this population, but also an alien mitotype similar to those of individuals from the Rostov region (Fig. 1).
"This result may indicate the present or past existence of a hybrid zone between the northern form and the 'Don' lineage of the southern form," says study co-author Marina Baskevich, PhD, senior researcher. Another co-author of the study from the Institute of Ecology and Evolution of the Russian Academy of Sciences, PhD, senior researcher Lyudmila Khlyap, notes the unique nature of hybridization for the genus Sicista.
The practical significance of this study lies in its contribution to the study of biodiversity and the patterns of formation of the Palearctic rodent fauna.
The work was published in the journal Animals: Bogdanov, A.S.; Rozhkova, D.N.; Khlyap, L.A.; Baskevich, M.I. Multi-Level Molecular Differentiation of Populations of the Strand's Birch Mouse Sicista strandi (Rodentia, Dipodoidea). Animals 2025, 15, 2605.
Presented by Baskevich M.I., Senior Researcher, Microevolution Lab, IEE RAS.