TY - JOUR

T1 - Experimental evidence for emerging speciation in the Olkhon mountain vole (Rodentia: Arvicolinae)

AU - Bikchurina, Tatiana

AU - Moroldoev, Igor

AU - Lopatina, Natalia

AU - Rubtsova, Daria

AU - Pozdnyakova, Evgenia

AU - Litvinov, Yuri N.

AU - Borodin, Pavel

N1 - Bikchurina, T., Moroldoev, I., Lopatina, N. et al. Experimental evidence for emerging speciation in the Olkhon mountain vole (Rodentia: Arvicolinae). Mamm Biol (2026). https://doi.org/10.1007/s42991-025-00561-4 The study was supported by the Ministry of Education and Science of Russian Federation, grant numbers #FWNR-2022-0015 and #FSUS-2024-0018. Field research and animal husbandry were supported by the Program of Fundamental Scientific Research of the State Academies of Sciences, grant number #FWGS-2026-0008. We thank the Core Facility for Microscopy of Biological Objects of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia (regulation no. 3054) for granting access to microscopic equipment.

PY - 2026/1/7

Y1 - 2026/1/7

N2 - The formation of reproductive isolation is a snowball-like process in which initial incompatibilities are often obscured by those accumulated during or after speciation. The Olkhon mountain vole or Olkhon vole (Alticola olchonensis), a taxon with unclear taxonomic status, provides an intriguing model to explore the early stages of peripatric speciation. A. olchonensis is a closely related species to A. tuvinicus; the latter includes two geographically isolated forms (Tuva and Khuvsgul). We examined reproductive performance, spermatogenesis dynamics, and chromosome synapsis and recombination characteristics of the all parental groups, their F1 and F2 hybrids, and backcrosses. While most F1 hybrids were fertile, they showed abnormalities in sperm morphology. F1 hybrids between Olkhon and Khuvsgul voles, as well as F2 hybrids and half of the backcrosses between Olkhon and Tuva voles, exhibited partial or extensive chromosome asynapsis and drastically reduced spermatid counts. Asynapsis could lead to the observed meiotic failure. Our findings indicate that the Olkhon vole is undergoing the early stages of reproductive isolation formation and thus speciation.

AB - The formation of reproductive isolation is a snowball-like process in which initial incompatibilities are often obscured by those accumulated during or after speciation. The Olkhon mountain vole or Olkhon vole (Alticola olchonensis), a taxon with unclear taxonomic status, provides an intriguing model to explore the early stages of peripatric speciation. A. olchonensis is a closely related species to A. tuvinicus; the latter includes two geographically isolated forms (Tuva and Khuvsgul). We examined reproductive performance, spermatogenesis dynamics, and chromosome synapsis and recombination characteristics of the all parental groups, their F1 and F2 hybrids, and backcrosses. While most F1 hybrids were fertile, they showed abnormalities in sperm morphology. F1 hybrids between Olkhon and Khuvsgul voles, as well as F2 hybrids and half of the backcrosses between Olkhon and Tuva voles, exhibited partial or extensive chromosome asynapsis and drastically reduced spermatid counts. Asynapsis could lead to the observed meiotic failure. Our findings indicate that the Olkhon vole is undergoing the early stages of reproductive isolation formation and thus speciation.

KW - Chromosome synapsis

KW - Homologous recombination

KW - Male hybrid sterility

KW - Mountain voles

KW - Reproductive isolation

KW - Spermatogenetic abnormalities

UR - https://www.scopus.com/pages/publications/105026907714

UR - https://www.mendeley.com/catalogue/c70e4d71-9a7a-315b-8fdb-f80d31569139/

U2 - 10.1007/s42991-025-00561-4

DO - 10.1007/s42991-025-00561-4

M3 - Article

JO - Mammalian Biology

JF - Mammalian Biology

SN - 1616-5047

ER -