Not all reindeer (Rangifer tarandus) spend the winter in Santa’s enclosure, preparing for the biggest present voyage of the year. Some separated from their Nordic cousins and settled on the islands of the Svalbard archipelago – even further north than Santa’s Village. Approximately 8000 years BP, less than 100 individuals form Russia colonised Svalbard, dispersing via Novaya Zemlya and the Franz Josef Land archipelago (Dussex et al., 2023). Since then, this small Arctic population has abandoned migration and chosen its own version of Márquez – Thousands Years of Solitude. Isolation, ecological changes and genetic forces drove Svalbard reindeer to develop unique adaptations, differentiating them into an endemic subspecies Rangifer tarandus platyrhynchus.

The changes in appearance are visible at first glance (Fig. 1, Fig. 2). Compared with mainland reindeer (Fig. 3), their insular relatives are stockier, smaller in size, with thicker fat layer and insulating fur. Their bodies are compact to minimise the risk of frostbite, hence shorter tails, ears, and legs. All these adaptations are believed to grant reindeer a special tolerance to cold and wind. To investigate this distinctiveness further, scientists analysed the primary source of every biological variability – DNA (Dussex et al., 2025).

The study selected genes responsible for these unique phenotypic traits, highlighting the importance of bone density, cartilage development, and tibia measurements. Surprisingly, even a gene associated with dwarfism in humans was found in reindeer genome.

Fig. 1. A Svalbard reindeer feeding on Tempelfjorden on Spitsbergen in late April, photographed by Bjørn Christian Tørrissen, under Creative Commons Deed – Attribution-ShareAlike 4.0 International – Creative Commons.

Morphology, however, is not the only characteristic distinguishing Svalbard reindeer. Arctic climate forces adaptation in nearly all its inhabitants – including flora. Since lichens – common reindeer winter food – are scarce on the archipelago, Svalbard reindeer have altered their diet to survive. They feed mostly on mosses (bryophytes) and small plants found under the snow cover. Latest research showed that, to deposit more energy from this diet, this polar subspecies has changed on a genetic level. For example, it developed unique alleles of genes related to metabolism, providing higher glycogen uptake and increasing chances of surviving periods of undernourishment.

The drastic annual shifts in daylight also affect reindeer biology. They carry a significantly distinctive variant of a gene partly regulating circadian rhythm, although the consequences of such a change are still under investigation. Genetic analyses indicated some divergence in genes associated with vision as well. While the exact effects of these changes on visual perception remain unknown, it is unsurprising that these animals developed mechanisms to possibly cope with longer periods of light deficient.

Fig. 2. Svalbard reindeer on Spitsbergen, photographed by Perhols, under Creative Commons Deed – Attribution 2.5 Generic – Creative Commons.

Fig. 3. Reindeer Rangifer tarandus photographed in Sweden by Alexandre Buisse, under Creative Commons Deed – Attribution-ShareAlike 3.0 Unported – Creative Commons.

New discoveries usually raise new questions. What can be said with a high dose of certainty is that avoiding Santa’s sleigh was not the cause of Rangifer tarandus platyrhynchus differentiation. Nevertheless, it cannot be overlooked that the climate crisis we face today is caused mainly by anthropogenic factors. Studies on Rangifer tarandus suggest that ongoing warming may significantly affect the size of mainland populations (Canteri et al., 2025). Considering the narrow distribution of their insular counterparts and their exceptional adaptation to cold environments, it can be presumed that Svalbard reindeer may be even more strongly affected by climate change. Although they may wish to escape Santa, his annual carbon footprint will certainly reach them wherever they are.

References

• Dussex, N., Tørresen, O. K., van der Valk, T., Le Moullec, M., Veiberg, V., Tooming-Klunderud, A., … & Martin, M. D. (2023). Adaptation to the High-Arctic island environment despite long-term reduced genetic variation in Svalbard reindeer. iScience 26, 107811. Article ADS PubMed PubMed Central.
• Dussex, N., Bieker, V. C., Sun, X., Le Moullec, M., Ersmark, E., Røed, K. H., … & Martin, M. D. (2025). The Genomic Basis of the Svalbard Reindeer’s Adaptation to an Extreme Arctic Environment. Genome Biology and Evolution, 17(9), evaf160.
• Canteri, E., Brown, S. C., Post, E., Schmidt, N. M., Nogues-Bravo, D., & Fordham, D. A. (2025). Mismatch in reindeer resilience to past and future warming signals ongoing declines. Science Advances, 11(33), eadu0175.