Researchers have sequenced the full genome of a woolly rhinoceros from a 14,400-year-old wolf puppy's stomach contents, offering insights into the species' final days before extinction. The discovery reveals a genetically healthy population on the brink of disappearance. This breakthrough marks the first time such a genome has been extracted from one animal's digestive remains.
In a pioneering achievement for paleogenomics, scientists dissected the frozen remains of an Ice Age wolf puppy discovered near the Siberian village of Tumat in 2011 and 2015. The 2022 lab examination uncovered partially digested woolly rhinoceros meat in the puppy's stomach, dating back 14,400 years. DNA analysis confirmed the meat belonged to Coelodonta antiquitatis, the woolly rhinoceros, a massive herbivore that roamed Eurasian tundras.
"Sequencing the entire genome of an Ice Age animal found in the stomach of another animal has never been done before," stated Uppsala University paleogeneticist Camilo Chacón-Duque, a co-author of the study. Despite the challenges of degraded DNA from permafrost preservation and separating rhino sequences from the wolf's, Stockholm University's Sólveig Guðjónsdóttir and colleagues successfully assembled the full genome.
The genome indicates the rhino came from a large, healthy population free of inbreeding signs, such as long stretches of homozygous genes. This contrasts with expectations, as woolly rhinos vanished from the fossil record around 14,000 years ago, just 400 years later. Their range had contracted eastward since 35,000 years ago, with the last holdouts in northeastern Siberia.
Comparisons with a 49,000-year-old specimen from nearby Rakvachan show the population's effective size—breeding individuals contributing to the gene pool—dropped sharply from about 15,600 to 1,600 between 114,000 and 63,000 years ago, then stabilized. Ecologists note that 1,600 exceeds the 1,000 threshold needed to avoid genetic pitfalls like inbreeding and drift.
A prior genome from 18,400 years ago also showed stability, suggesting the end came abruptly after 14,400 years ago. Likely culprit: the Bølling–Allerød interstadial, a rapid warming from 14,700 to 12,800 years ago, which melted ice sheets and transformed habitats too quickly for adaptation.
"In the current biodiversity crisis driven by anthropogenic climate change, it becomes increasingly important to understand the underlying drivers of population declines and the propensity of species going extinct," wrote Guðjónsdóttir and colleagues in their paper published in Genome Biology and Evolution (DOI: 10.1093/gbe/evaf239). Future sequencing of even later specimens could clarify if extinction left genomic traces.