These baboons borrowed a third of their genes from their cousins

Deze bavianen leenden een derde van hun genen van hun neven

The vast majority of baboons in Kenya’s Amboseli Basin carry genes from a closely related species, new study finds in the journal Science. Credit: Arielle Fogel, Duke University

New genetic analyzes of wild baboons in southern Kenya reveal that most of them carry traces of hybridization in their DNA. As a result of crossings, about a third of their genetic makeup consists of genes from another, closely related species.

The research took place in a region near Kenya’s Amboseli National Park, where yellow baboons occasionally meet and mingle with their anubis baboon neighbors who live in the northwest.

Researchers have monitored these animals almost daily since 1971, noting when they mate with outsiders and how the resulting offspring fared throughout their lives as part of the Amboseli baboon research projectone of the longest-running field studies of wild primates in the world.

Yellow baboons have a tan coat with white cheeks and undersides. Anubis baboons have green-gray fur and males with shaggy manes around their heads. Although they are different types of that diverged 1.4 million years ago, they can hybridize where their ranges overlap.

In all respects, the descendants of these unions are doing just fine. Fifty years of observations yielded no clear signs that hybrids are doing worse than their counterparts. Some even do better than expected: baboons that carry more Anubis DNA in their genome mature faster and form stronger social bonds, and males are more successful at winning mates.

But new genetic findings published Aug. 5 in the journal Science suggest that appearances are deceiving.

The research sheds light on how species diversity on Earth is preserved even when genetic lines between species are blurred, said Duke University professor Jenny Tung, who led the project with her PhD students Tauras Vilgalys and Arielle Fogel.

Interspecies mating is surprisingly common in animals, said Fogel, who has a Ph.D. candidate in the Duke University program in genetics and genomics. About 20% to 30% of monkeys, monkeys and others primate species cross and mix their genes with others.

Even modern people carry a mix of genes from now-extinct relatives. As much as 2% to 5% of the DNA in our genomes points to past hybridization with the Neanderthals and Denisovans, ancient hominids that our ancestors encountered and mated with as they migrated from Africa to Europe and Asia. Those liaisons left behind a genetic legacy that is still present today that influences our risk of depression. blood clotseven tobacco addiction or complications from COVID-19.

The researchers wanted to gain insight into the potential costs and benefits of this genetic admixture in primates, including humans. But modern humans stopped interbreeding with other hominids tens of thousands of years ago when all but one species – our own – became extinct. However, Amboseli’s wild baboons make it possible to study primate hybridization that is still ongoing.

The researchers analyzed the genomes of some 440 Amboseli baboons, spanning nine generations, looking for bits of DNA that may have been inherited from Anubis immigrants.

They found that all baboons in the Amboseli Basin in southern Kenya today are a mix, with anubis DNA making up about 37% of their genomes on average. Some have Anubis ancestry due to crosses that occurred quite recently, within the last seven generations. But for nearly half of them, the mixing happened further back, hundreds to thousands of generations ago.

During that time, the data shows that certain bits of Anubis DNA came at the expense of the hybrids they inherited, affecting their survival and reproduction in such a way that these genes are less likely to appear in the genome of their offspring today, Vilgalys said, now a postdoctoral researcher at the University of Chicago.

Their results are consistent with genetic research in humans, suggesting that our early ancestors also paid a price for hybridization. But exactly what the Neanderthal and Denisovan genes did to harm them has been difficult to determine from the limited fossil and DNA evidence available.

The researchers say the baboons at Amboseli provide clues as to the cost of the hybridization. Using RNA sequencing to measure gene activity in the baboons blood cellsthe researchers found that natural selection is more likely to remove bits of borrowed DNA that act as switches, turning other genes on and off.

The next step, Fogel said, is to more accurately determine what ultimately affects these hybrid baboons’ ability to survive and reproduce.

Genomic data allows researchers to look back many generations and study historical processes that can’t be seen directly in the field, Vilgalys said.

“But you have to look at the animals themselves to understand what genetic changes actually mean,” Tung said. “You need both fieldwork and genetics to understand the whole story.”

“We’re not saying this is what the Neanderthal and Denisovan genes did in humans,” added Tung, now at the Max Planck Institute for Evolutionary Anthropology in Germany. “But the baboon case makes it clear that genomic evidence for the costs of hybridization may be consistent with animals that not only survive, but often thrive.”

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More information:
Tauras P. Vilgalys et al, Selection against gene mixing and divergence in a long-term primate field study, Science (2022). DOI: 10.1126/science.abm4917.

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Duke University

Quote: These baboons borrowed a third of their genes from their cousins ​​(2022, August 4), retrieved August 4, 2022 from

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