During the last glacial period (~118 to 11.7 ka), the Arctic has been characterized by a major redistribution of flora and fauna as a consequence of extreme climatic fluctuations, with associated glacial advances and retreats, sea-level changes, and shifting sea ice extent. In the high-latitude regions of Northern Europe that are currently subject to rapid climate warming, we lack a comprehensive understanding of faunal biodiversity in the last glacial period due to the extreme rarity of preserved organic remains. Here, we present a stratified sediment deposit with a diverse faunal composition preserved in a bone-bearing layer in Arne Qvamgrotta, part of the Storsteinhola cave system (68.10° N 16.38° E) in Northern Norway. Chronological analyses of sediments and bones including radiocarbon, optically stimulated luminescence, uranium–thorium, and phylogenetic dating place the faunal assemblage in Marine Isotope Stage 5a (MIS 5a, Odderade interstadial, ~85 to 71 ka). Combining comparative osteology and bulk-bone metabarcoding, we identify 46 taxa, including mammals, birds, and fish, with several species not previously found in Fennoscandia. The fauna implies a nonanalogous cold-adapted coastal community, with close proximity to sea ice and nearby freshwater bodies. Mitogenome analyses of a subset of taxa identify extinct lineages which attest to a lack of habitat tracking and the absence of a local refugium during the subsequent fully glaciated periods. This faunal record demonstrates long-term faunal dynamics and coastal environmental conditions during MIS 5a in the European Arctic.

Humans have relied on animal fur for centuries, yet fur farming only began recently during the mid-19th Century. Little is known about this incipient domestication or the genomic processes involved. Domestication may involve founder effects, population bottlenecks and low population size, which, when combined with intense artificial selection, lead to inbreeding, a limited gene pool and reduced fitness. The arctic fox (Vulpes lagopus) has been farmed intensively since the early 1900s and has been artificially selected for economic phenotypes. We investigated the origin of these lineages and the genomic consequences of intensive farming by comparing the genomes of farmed and wild arctic foxes from across their range. Our research indicates recent inbreeding through long Runs of Homozygosity and reduced genomic variation in farmed foxes relative to their respective wild populations. We identified a coastal ecotype origin for all Fennoscandian farmed arctic foxes, aligning them phylogenetically with the wild Icelandic population, a geographically isolated and phenotypically distinct coastal lineage. The depleted genome-wide heterozygosity and increased recent inbreeding in farmed fox lineages is consistent with a heavy consequence of domestication, shedding light on the demographic history and genomic consequences of human manipulation. We highlight the need for increased genomic investigations into fur farm populations to understand the incipient domestication process and uncover the cost of intense farming. The genomic consequences of domestication must be considered in the management of fur farms, with actionable steps needed to prevent descendants of escaped farmed foxes from polluting the gene pool in the wild through introgression.

Accelerating climate change is causing severe habitat fragmentation in the Arctic, threatening the persistence of many cold-adapted species. The Scandinavian arctic fox (Vulpes lagopus) is highly fragmented, with a once continuous, circumpolar distribution, it struggled to recover from a demographic bottleneck in the late 19th century. The future persistence of the entire Scandinavian population is highly dependent on the northernmost Fennoscandian subpopulations (Scandinavia and the Kola Peninsula), to provide a link to the viable Siberian population. By analyzing 43 arctic fox genomes, we quantified genomic variation and inbreeding in these populations. Signatures of genome erosion increased from Siberia to northern Sweden indicating a stepping-stone model of connectivity. In northern Fennoscandia, runs of homozygosity (ROH) were on average ~1.47-fold longer than ROH found in Siberia, stretching almost entire scaffolds. Moreover, consistent with recent inbreeding, northern Fennoscandia harbored more homozygous deleterious mutations, whereas Siberia had more in heterozygous state. This study underlines the value of documenting genome erosion following population fragmentation to identify areas requiring conservation priority. With the increasing fragmentation and isolation of Arctic habitats due to global warming, understanding the genomic and demographic consequences is vital for maintaining evolutionary potential and preventing local extinctions.