Scientists analyzed the genome of a 14,400-year-old woolly rhinoceros found in the stomach of an ancient wolf pup. The results give experts insight into the rapid extinction of the woolly rhinoceros, likely due to climate change.
Tissue from the woolly rhinoceros (Coelodonta antiquitatis) was found inside the mummified remains of a wolf cub, which was first discovered in Siberian permafrost in 2011. A subsequent autopsy of the puppy revealed that it had last eaten. It turns out it was eating one of the last woolly rhinos on Earth. But now scientists have discovered a way to sequence an animal’s complete genome from a piece of undigested rhino meat.
“Sequencing the entire genome of an Ice Age animal found in the stomach of another animal has never been done before,” Camilo Chacón-Duque, a bioinformatician at Uppsala University in Sweden and co-author of the new study, said in a statement.
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In a new study published Wednesday (January 14) in the journal Genome Biology and Evolution, researchers analyzed woolly rhinoceros muscle tissue and compared it to older examples to investigate population size and levels of inbreeding in species on the verge of extinction. The mass provided unprecedented information about the woolly rhinoceros’ demise.
Many extinct species leave behind clues about their geographic range, population size, and genome decline. When animal populations decline, animals may become concentrated in certain areas. For example, the woolly mammoth (Mammuthus primigenius) lived on a remote Siberian island until about 4,000 years ago. However, the small population contributed to inbreeding, and this lack of genetic diversity may have ultimately determined the woolly mammoth’s fate. (However, other research suggests that the mammoths on these islands died in a random mysterious event.)
However, woolly rhinos were widespread in northern Eurasia until about 35,000 years ago. Its geographic range shrank over time, and the species became concentrated in northeastern Siberia, where it became extinct around 14,000 years ago. A piece of woolly rhinoceros tissue found in a wolf pup’s stomach has been carbon dated to be 14,400 years old. This means the woolly rhinoceros is likely the last of its kind.
The researchers generated the woolly rhinoceros genome from preserved muscle tissue and compared it with two older genomes, one from 18,000 years ago and one from 49,000 years ago. They found that the three rhinos had similar levels of inbreeding and genetic diversity, suggesting that there must have been a relatively stable woolly rhino population in northern Siberia until at least 14,400 years ago, after which it rapidly became extinct.
“Our results show that woolly rhinos maintained viable populations for 15,000 years after the first humans arrived in northeastern Siberia, suggesting that climate warming, rather than human hunting, was the cause of their extinction,” study co-author Rav Dalen, professor of evolutionary genomics at the Swedish Center for Paleogenetics, said in a statement. This result builds on previous work by several of the same researchers.
Towards the end of the Pleistocene (last ice age), a rapid change in the world’s climate occurred and many large mammals became extinct. The disappearance of the woolly rhino coincides with a period called the Boring-Allerod Interperiod, when the Northern Hemisphere’s climate rapidly warmed from about 14,700 to 12,900 years ago. This dramatic warming may have caused the woolly rhinoceros, a cold-adapted herbivore, to lose its favorite food, contributing to its rapid decline.
Although the new genome does not solve all the mysteries surrounding the woolly rhino’s extinction, researchers have demonstrated that it is possible to recover DNA from one animal from within another.
“Extracting the complete genome from such a rare sample was very exciting, but also very difficult,” study lead author Solveig Gjonsdottir, a researcher at Stockholm University, said in a statement.
The researchers hope their results will pave the way for future DNA and genomic analysis of animal tissue from “unlikely sources.”
Mammoth Quiz: Test your knowledge about Ice Age beasts
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