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 and all other populations investigated, which might warrant a
revision of their taxonomic classification. The inferred low genetic
diversities at the western edge of their distribution are especially
worrisome as they are currently experiencing strong population declines
and major habitat changes, which can be especially detrimental when
standing variation is low. Thus, there is a pressing need to revise the
species' conservation status.