Ruminations on the hologenomics of prehistoric reindeer (Rangifer tarandus)

Abstract

What we can learn from prehistoric reindeer

Global climate is a major challenge of our time, and climate warming is especially rapid and dangerous in the Arctic. One arctic animal which will be greatly affected in the future is the reindeer. Luckily, we can learn from prehistory how reindeer have fared during past episodes of climate warming at the end of the last ice age. Comparing how reindeer lived in the past with reindeer which live today, will help to predict how reindeer will fare in the future.

The research here aims to find out what we can learn about prehistoric reindeer from ancient DNA preserved in their bones and teeth, some of which are up to 50,000 years old. Since the DNA was highly degraded and difficult to work with, specialized techniques were required. Despite these challenges, ancient DNA is a very valuable and versatile tool because it gives us unique opportunities to directly investigate prehistoric reindeer.

Here we shed light on three aspects of prehistoric reindeer: First, we show how historical hunting on Svalbard has negatively impacted the gene pool of Svalbard reindeer in the long term. Second, we compared microbes from reindeer teeth and found that some aspects of the reindeer mouth microbiome are stable, while others have changed over time. Third, we investigated the evolutionary relationships between reindeer remains from all over the Arctic and northern Europe over the past 50,000 years, concluding that the reindeer population has been subject to major changes in size and that there have been several complete replacements of evolutionary lineages. Using ancient DNA made it possible to include reindeer from many places where they are now extinct. Overall, this thesis highlights how combining different types of ancient DNA data can inform about the ecology and evolution of ancient animals and potentially to help protect endangered wild animals from climate change.