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A research team from the Natural Resources Institute Finland (Luke) has sequenced the reindeer genome. The researchers identified several genes which have promoted the adaptation of reindeer to Arctic environments.

Luke’s research team sequenced the entire genome of reindeer (Rangifer tarandus), named genes and defined their functions. This project resulted in the reindeer reference genome, to which genetic samples of reindeer and their wild relatives, i.e. different deer species and caribou, can be compared.

Photo: Juha Kantanen

According to the study, the reindeer genome consists of nearly three million base pairs, from which the researchers identified more than 27,000 genes. An article on the sequencing of the reindeer genome was published in Scientific Reports journal at the beginning of June.

While genomic methods have  been used in studies of many domestic animals for many years, research in reindeer  is in its infancy. The reindeer genome is the first reference genome of a mammal species published and coordinated by a Finnish research team. Currently, Luke is also sequencing the reference genome of Finnsheep.

Partners of Luke’s research team in the reindeer genome study come from the Norwegian University of Life Sciences and BGI-Genomics, a China-based company. The study was funded by the Academy of Finland and Luke.

The reference genome forms the basis of genetic analyses

Juha Kantanen, director of the study and research professor at Luke, says that the reference genome of reindeer lays an important foundation for genetic research and animal breeding. It is a kind of data library or map for analyses on reindeer genes.

“Genomic research helps to evaluate the diversity of different flocks to promote the maintenance of the vitality of the reindeer population. What is more, genome research sheds light on the reindeer domestication history and, for example, helps to sequence Finnish forest reindeer populations in detail”, Kantanen says.

Luke’s research team characterized the reindeer reference genome by sequencing DNA samples taken from Juhani Maijala’s male reindeer. The sample underwent complex de novo sequencing approach to make the reference genome sufficiently comprehensive. Genes were identified using the well-known reference genomes of five other mammals, including human and dog genomes.

In addition to the reference genome, genomes were sequenced from 23 reindeer individuals using samples that the research team obtained from its international partners, such as, reindeer and wild deer samples from Norway, Svalbard, Novaya Zemlya and Yamal Peninsula, as well as caribou samples from Alaska.

Genes reveal information about evolution

The reindeer genome tells the researchers about the evolution and domestication history of reindeer. Luke’s researchers sequenced reindeer genes that have significantly helped the species to adapt to environments in the Arctic. For example, the retina of reindeer has adapted to the polar night and the midnight sun, and genes that improve the sense of smell help reindeer to find food under the snow.

Photo: Mervi Honkatukia

“We also sequenced genes that affect the circadian rhythm, the fastest growing antler tissue among all animals, the intense vitamin D metabolism and the ability to withstand pain induced by cold weather”, Kantanen says.

Genomic research showed that reindeer have been domesticated from wild tundra deer at least twice, as the genome of Fennoscandian reindeer differs slightly from their near relatives living in Siberia and Alaska. Kantanen assumes that, during the previous ice age, reindeer populations found refugia in different parts of the Eurasian continent.

“The ice age has also left other signatures on the reindeer genome. The most recent ice age more than 10,000 years ago significantly reduced the genetic diversity of the tundra reindeer, a wild ancestor of the Fennoscandian domestic reindeer. This observation shows that any radical climate change has a significant impact on the genetic diversity of wild animals”, Kantanen concludes.

Weldenegodguad, M., Pokharel, K., Ming, Y. et al. Genome sequence and comparative analysis of reindeer (Rangifer tarandus) in northern Eurasia. Sci Rep 10, 8980 (2020). https://doi.org/10.1038/s41598-020-65487-y

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