Search for the mythical Asian unicorn: New genetic clues emerge

In the remote, misty highland forests straddling Vietnam and Laos, a rare creature may still roam unseen. Known as the saola, this elusive animal was only discovered by scientists in 1992 and has since earned the nickname “Asian unicorn” due to its near-mythical status.

The saola looks like an antelope but is more closely related to cattle. Both males and females have a pair of long, straight horns that may be reminiscent of a unicorn’s single spike, when seen side on.

Mystery of the Asian unicorn

Even at the time of its discovery, the saola (Pseudoryx nghetinhensis) was already in trouble. Today, fewer than 100 are thought to remain – if they’re alive at all.

“Right now, the existence of live saolas can neither be proven nor disproven. The last evidence we have was from 2013, when one was captured on a camera trap,” said Nguyen Quoc Dung from the Forest Inventory and Planning Institute in Vietnam.

“But given the remoteness of its habitat, it is extremely difficult to say for sure whether there are still a few out there. There are some signs and indications that still give us hope.”

A surprising genetic discovery

Dung is part of an international research team that has now achieved something remarkable. Scientists from the University of Copenhagen and institutions across the globe have, for the first time, mapped the genome of the saola.

Until now, there was virtually no genetic data on this critically endangered species. The researchers worked with saola remains gathered from hunter households in the region.

Using fragments from these remains, they assembled complete genomes for 26 individuals. What they found reveals a new chapter in the Asian unicorn’s story – and possibly, a path forward for its survival.

“We were quite surprised to find that the saola is split into two populations with considerable genetic differences. The split happened between 5,000 and 20,000 years ago,” said Genís Garcia Erill, lead author of the study.

“That was completely unknown before, and there was also no way we could have known without genetic data. It is an important result because it affects how the genetic variation in the species is distributed.”

Loss of genetic diversity

The analysis also showed that both populations have been shrinking since the end of the last Ice Age.

Over the past 10,000 years, the total number of saolas likely never exceeded 5,000 individuals. This long decline has caused a gradual loss of genetic diversity in both groups – but not the same genetic diversity.

“This means that the genetic variation lost in each population complements the other. So, if you mix them, they could compensate for what the other is missing,” said Garcia Erill.

In short, the key to saving the saola might lie in bringing these two populations back together.

A plan for saola survival

The researchers used computer models to explore different scenarios for conservation. Their results suggest that mixing individuals from both populations in a captive breeding program could give the species its best shot at survival.

“If we can bring together at least a dozen saolas – ideally a mix from both populations – to form the foundation of a future population, our models show the species would have a decent chance of long-term survival,” noted Rasmus Heller, senior author of the study.

“But it hinges on actually locating some individuals and starting a breeding program. That has worked before when species were on the brink of extinction.”

New hope for the Asian unicorn

The researchers hope that the newly mapped genome will make it easier to locate any remaining saolas.

Until now, teams have searched using environmental DNA (eDNA) – traces of genetic material left behind in water, soil, or even inside leeches. These techniques depend on detecting tiny DNA fragments, which has proven difficult.

“Many researchers have unsuccessfully tried to find traces of saola through methods like environmental DNA in water and even in leeches, the blood suckers inhabiting the same habitat,” said study co-author Minh Duc Le of Vietnam National University.

“These techniques all rely on detecting tiny DNA fragments, and now that we know the complete saola genome, we have a much larger toolkit for detecting those fragments.”

The future of Asian unicorns

Even if none of the enigmatic Asian unicorns are ever found, this new information could still play a role in the future.

“Our results could, in theory, be used if we were ever to succeed in bringing the saola back through genetic de-extinction technologies, which are a hot topic right now,” said Heller.

“In that case, our new insights into saola genetic variation could make a huge difference in creating a viable population.”

Still, there’s a sense of urgency and realism behind the hope. Heller noted that scientists have been searching for saolas since the 1990s, and it’s only gotten harder, because there were more of them back then.

“I’m not overly optimistic, I have to admit – but I really hope the saola is still out there,” concluded Heller.

The full study was published in the journal Cell.

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