Periodic Reporting for period 1 - SURVIVOR (Historic response of a wide-ranging carnivore to climate change)
Periodo di rendicontazione: 2018-06-01 al 2020-05-31
The cave lion is an extinct relative of the African lion, which lived until around fourteen-thousand years ago. If we could better understand the reasons that this animal went extinct (for example was it due to the climate warming, being hunted by humans, or their habitat disappearing?), we could use this information to help protect its current-day relatives. These relatives are some of the most endangered species on the planet, such as Amur leopards, Iberian lynxes, and Asiatic cheetahs.
On the other hand, wolves lived at a similar time to cave lions, but are still around today and so on the face of it, did not go extinct. However, when we look at the genetics of very old fossils from wolves, we see that there were varieties around in the past that are not here today, so like the cave lion, some wolves did go extinct. What are the differences between these evolutionary "success" and "failure" examples? It may be that they naturally had genetic traits that better enabled them to adapt to the quickly warming climate at the time, or perhaps they inherited those traits by breeding with closely related species that we know existed at the time? If we knew that this breeding between closely related species was needed to stop them from going extinct, it might make us change the way that we manage similar species today.
This research project aimed to get a better understanding why cave lions went extinct and wolves did not. Specifically, we used DNA from the bones of these animals (up to 40,000 years old) to attempt to answer the questions: 1) When did these populations or species go extinct? 2) How are the extinct populations related to the living ones? 3) Are there any genetic traits that are associated with these species either going extinct or surviving? 4) Can this tell us anything about how animals are likely to respond to the changing climate in the future?
On the other hand, wolves lived at a similar time to cave lions, but are still around today and so on the face of it, did not go extinct. However, when we look at the genetics of very old fossils from wolves, we see that there were varieties around in the past that are not here today, so like the cave lion, some wolves did go extinct. What are the differences between these evolutionary "success" and "failure" examples? It may be that they naturally had genetic traits that better enabled them to adapt to the quickly warming climate at the time, or perhaps they inherited those traits by breeding with closely related species that we know existed at the time? If we knew that this breeding between closely related species was needed to stop them from going extinct, it might make us change the way that we manage similar species today.
This research project aimed to get a better understanding why cave lions went extinct and wolves did not. Specifically, we used DNA from the bones of these animals (up to 40,000 years old) to attempt to answer the questions: 1) When did these populations or species go extinct? 2) How are the extinct populations related to the living ones? 3) Are there any genetic traits that are associated with these species either going extinct or surviving? 4) Can this tell us anything about how animals are likely to respond to the changing climate in the future?
We sampled DNA from over 250 ancient wolves and cave lions bones, from a range of locations across the Northern Hemisphere, and from a range of ages, some of which being over 100 thousand years ago. Our results show that for both wolves and cave lions there used to exist at least two distinct evolutionary lineages, but while both of these lineages went extinct for cave lions, one survived for wolves. In cave lions these lineages had different distributions: One occupying North-East Siberia and Beringia, and the other occupying the areas to the West of Eastern Siberia, as far as Central Europe. For wolves, there was a population turnover that occurred during the Last Glacial Maximum (approximately 22 thousand years ago). Prior to this time, all our wolf samples belong to the now extinct "Pleistocene wolf" lineage, whereas after this time they all belong to the "Holocene wolf" lineage that is widespread today. It is not clear where the modern wolf lineage originated, but our results suggest that it was unlikely to be from Siberia or Eastern Europe.
Included in this study were two very well preserved cave lions cubs "Boris" and "Spartak" that were found in such close proximity that they were originally thought to be siblings, however it was later demonstrated that they were separated in age by over 10 thousand years (https://siberiantimes.com/science/casestudy/news/cute-first-pictures-of-new-50000-year-old-cave-lion-cub-found-perfectly-preserved-in-permafrost-of-yakutia/). Boris was shown to be 46 thousand years old and Spartak 31 thousand years old.
One of the important samples for the wolf analysis was an exceptionally well-preserved wolf pup, which we radiocarbon dated to 18 thousand years old. We sequenced the genome of this individual and showed that it was male, and our collaborators in Russia who provided the sample named the individual "Dogor" which means "Friend" in Yakut. Interestingly, we were unable to assign this specimen to the Pleistocene wolf, modern wolf or the dog lineage, suggesting that it may be very close to all three. This result was disseminated very widely via numerous media outlets (e.g: https://www.bbc.co.uk/news/world-europe-50586508).
Included in this study were two very well preserved cave lions cubs "Boris" and "Spartak" that were found in such close proximity that they were originally thought to be siblings, however it was later demonstrated that they were separated in age by over 10 thousand years (https://siberiantimes.com/science/casestudy/news/cute-first-pictures-of-new-50000-year-old-cave-lion-cub-found-perfectly-preserved-in-permafrost-of-yakutia/). Boris was shown to be 46 thousand years old and Spartak 31 thousand years old.
One of the important samples for the wolf analysis was an exceptionally well-preserved wolf pup, which we radiocarbon dated to 18 thousand years old. We sequenced the genome of this individual and showed that it was male, and our collaborators in Russia who provided the sample named the individual "Dogor" which means "Friend" in Yakut. Interestingly, we were unable to assign this specimen to the Pleistocene wolf, modern wolf or the dog lineage, suggesting that it may be very close to all three. This result was disseminated very widely via numerous media outlets (e.g: https://www.bbc.co.uk/news/world-europe-50586508).
We are currently investigating if we can find evidence of inbreeding and natural selection in the genomes of these individuals, to investigate what the differences may be between these evolutionary "successes" and "failures". The potential impacts of these findings are to gain a better understanding of why some species are able to survive long-term climate changes, whereas others are not. If we can get a better understanding of this process, and these differences, it will allow us to be better able to predict which species are likely to go extinct in the future.