A recent genetic study reveals surprising evolutionary history and serious conservation concerns of the Siberian flying squirrel.
The Siberian flying squirrel (Pteromys volans) is a nocturnal and arboreal rodent, which inhabits the boreal taiga forests from eastern Russia to Finland and Estonia. Despite its wide distribution, little was previously known about the genetic structure and history of this elusive species. Using genome-wide single nucleotide polymorphisms (SNPs) and mitochondrial DNA (mtDNA), researchers from the Finnish Museum of Natural History, University of Helsinki, University of Oulu and from Russia investigated population structure, genetic diversity, and connectivity between individuals in different parts of the range.
Genetic diversity was found to be lowest in Finland, the species' westernmost range, and highest in the Russian Far East, particularly in the Sikhote-Alin region. This pattern supports the theory of a relatively recent westward expansion of the species from its eastern glacial refugia. Most notably, the Far Eastern population showed such strong genetic divergence that it may represent a separate subspecies, or even a distinct species altogether.
"These findings indicate a clear need for a taxonomic re-evaluation," says lead author Fernanda Ito. "The significant genetic divergence in the Sikhote-Alin population suggests it could represent a new, undescribed lineage."
Protecting the Siberian flying squirrel helps other species of the taiga
Beyond taxonomy, the study raises red flags for conservation. The western populations, particularly in Finland, are facing population declines and habitat loss. With already low genetic diversity, their capacity to adapt to environmental changes is likely to be compromised.
"This is especially concerning because Finland hosts the largest population of Siberian flying squirrels in the European Union," says Jaana Kekkonen, the principal investigator of the study. "With that comes a particular responsibility for safeguarding the species."
In practice, the results underscore the importance of managing forest landscapes to preserve suitable habitats, particularly mature boreal forests that flying squirrels rely on. Because of its specialised habitat requirements, the Siberian flying squirrel is considered an umbrella and indicator species. This means that protecting it could also benefit a host of other forest-dependent wildlife.
The study not only calls attention to the pressing need for updated conservation assessments across the species' range but also highlights the broader importance of preserving the biodiversity of the Eurasian taiga, one of the world's largest and most threatened forest ecosystems.
Most of Finland belongs to the taiga region - only the northernmost part has tundra, and a small area in the far south is temperate mixed forest. Most of Russia is also covered by taiga: this zone stretches from Karelia all the way to the Pacific Ocean. North of it lies tundra, and to the south, deciduous forests and steppe regions.
"This study not only shows the importance of understanding a species' evolution for its conservation but also opens up new possibilities to develop genetic monitoring tools that can support evidence-based management." says Assistant Prof. Stefan Prost, a co-author of the study.
As a flagship species for this biome, the Siberian flying squirrel may help rally public interest in conserving both the animal itself and the rich forest habitats it calls home.
