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

Abstract

Aim: Maintenance of genetic diversity and connectivity is important for the potential of a species to adapt to environmental changes. Studying these can also assist in understanding local patterns for planning conservation measures. The Siberian flying squirrel (Pteromys volans) is experiencing population declines in parts of its range and is listed as endangered in some countries. Here we studied the population genetic diversity and structure of the species in five areas across its distribution range in the Eurasian taiga forest zone. Location: Multiple sites throughout Finland and three regions in Russia. Methods: We used genome-wide single nucleotide polymorphisms (SNPs) to study genetic diversity within sampling locations. We estimated population structure and level of connectivity between the sampling locations. To understand potential dispersal barriers between the locations we used an estimated effective migration model. In addition, we used mitochondrial DNA (mtDNA) from the same populations to study historical ancestry and species delimitation. Results: The species presents low nucleotide diversity and heterozygosity in all locations studied. Locations in Finland, on the western edge of distribution, had the lowest diversities. In both marker types (genomic SNPs and mtDNA), Finland and Tyumen, in western Siberia, grouped together. Baikal, in East Siberia, separated from the western group indicating geographical barriers restricting gene flow. However, Baikal grouped more closely to western sites than with easternmost Sikhote-Alin, which likely constitutes a separate genetic lineage. Main conclusions: Our findings highlight the need for a taxonomic review and to determine the species conservation status across its entire distribution range. Sikhote-Alin has a different genetic lineage with higher genetic diversity. Finnish samples present very low genetic diversity, potentially due to declining populations as well as being located at the leading edge of range expansion. This can make them more susceptible to the adverse effects of habitat change.