Population structure of the endangered Siberian flying squirrel (Pteromys volans) revealed by genomic and mitochondrial data

The Siberian flying squirrel (Pteromys volans) is an arboreal rodent with a distribution range that covers large parts of the Eurasian taiga forest zone. However, extensive forestry has resulted in widespread local population declines and extinctions in recent decades. Even though it is widely distributed in Eurasia, almost nothing is known about its phylogeography. Here, we used genome-wide single nucleotide polymorphisms (SNPs) and mitochondrial DNA (mtDNA) to investigate population structure, connectivity, and genetic diversity in different sites throughout its distribution. Overall, the species shows low nucleotide diversity and heterozygosity. Locations in Finland, on the western edge of the distribution, had the lowest diversities in genomic SNPs and mtDNA, while individuals in the Far East (Sikhote-Alin, Russia) show the highest diversity. These findings fit with a rapid range expansion from the Far East to the west. We found a strong genetic differentiation between Sikhote-Alin ..., , # Data S1 - *P. volans* population structure

[https://doi.org/10.5061/dryad.3r2280grr](https://doi.org/10.5061/dryad.3r2280grr)

## Description of the data and file structure

Samples were obtained from Finland and Russia during the years of 2006 and 202. In Finland, the samples were obtained from several locations and grouped into two subgroups: Western and Eastern Finland. In Russia, the Siberian flying squirrel was sampled in three regions: Tyumen, Baikal, and Sikhote-Alin. Genomic DNA was extracted from individual frozen tissue samples using the NucleoSpin tissue kit (Macherey-Nagel®) following the manufacturer’s protocol. All DNA stocks were quantified and normalized to 12 ng/µL to be used for molecular processing. Double-digestion RADseq libraries were prepared using an adapted protocol for low-concentration samples, with the restriction enzymes PstI-HF™ and BamHI. Sequencing was performed using Illumina Novaseq6000 over one lane with 150 paired-end reads. While two mitochondria...,