Monday, July 1, 2024

[PaleoMammalogy • 2024] Temporal Dynamics of Woolly Mammoth Genome Erosion prior to Extinction


woolly mammoth Mammuthus primigenius wanders the frozen shore of Wrangel Island. 

in Dehasque, Morales, et al., 2024. 
    DOI: 10.1016/j.cell.2024.05.033    
 Artwork by Beth Zaiken

Highlights: 
• Analysis of long-term genomic changes using 21 high-coverage woolly mammoth genomes
• Severe bottleneck of the last surviving population when Wrangel Island was isolated
• The population partially recovered within a few generations and then remained stable
• Inbreeding depression and purging persisted for thousands of years after the recovery

Summary:
  A number of species have recently recovered from near-extinction. Although these species have avoided the immediate extinction threat, their long-term viability remains precarious due to the potential genetic consequences of population declines, which are poorly understood on a timescale beyond a few generations. Woolly mammoths (Mammuthus primigenius) became isolated on Wrangel Island around 10,000 years ago and persisted for over 200 generations before becoming extinct around 4,000 years ago. To study the evolutionary processes leading up to the mammoths’ extinction, we analyzed 21 Siberian woolly mammoth genomes. Our results show that the population recovered quickly from a severe bottleneck and remained demographically stable during the ensuing six millennia. We find that mildly deleterious mutations gradually accumulated, whereas highly deleterious mutations were purged, suggesting ongoing inbreeding depression that lasted for hundreds of generations. The time-lag between demographic and genetic recovery has wide-ranging implications for conservation management of recently bottlenecked populations.

Keywords: Mammuthus primigenius, woolly mammoth, extinction, ancient DNA, paleogenomics, mutation load, inbreeding, bottleneck, climate, Wrangel Island

The last woolly mammoth Mammuthus primigenius wanders the frozen shore of Wrangel Island. 
 Artwork by Beth Zaiken

 
M. Dehasque, H. E. Morales, et al. 2024. Temporal Dynamics of Woolly Mammoth Genome Erosion prior to Extinction. Cell.  DOI: 10.1016/j.cell.2024.05.033    

New genetic study reveals the woolly mammoths' journey towards extinction