New DNA insight may open door to saving northern white rhino on brink of extinction

Science

Genetic analysis has provided hope for the survival of a rhino sub-species that is perilously close to extinction.

When the world’s last male northern white rhino, Sudan, died in March, hope for the continued survival of his kind passed away with him.

However, since his death scientists have stepped up efforts to preserve the northern whites, employing the latest reproductive technologies to bring them back from the brink.

One of the key avenues being pursued is a “hybrid rescue” strategy, creating rhino embryos using sperm collected from northern whites before they died combined with eggs from the far more common southern variety.

Scientists hope that the resulting hybrid rhinos could be used to effectively resurrect this species, but there are concerns about whether they would grow up to be healthy and capable of producing offspring.

Now, a new paper published in the journal Proceedings of the Royal Society B has revealed an ancient link between the two sub-species that could make the process smoother than previously imagined.

DNA sampled from over 200 northern and southern rhinos revealed that during the last ice age the two groups, which in recent years have inhabited separate regions in central and southern Africa, mingled and mated with each other, sharing genetic information.

This suggests that as the continent cooled and grassland expanded to replace forest, the populations linked up.

“If they have been in genetic contact relatively recently – for example within the last 20,000 years – they may be less genetically incompatible than previously thought, making it more likely that hybrids could survive and reproduce,” explained Professor Michael Bruford, one of the study’s authors.

The only known hybrid in recent years was a female born in captivity in 1977, and while she lived 32 years in a zoo she never mated.

With just two female northern white rhinos remaining, the creation of hybrids to help bolster the population has been suggested as a key part of a future conservation strategy.

“We don’t know how they’d fare in the wild. But it is an option and with these data a more viable one than previously appreciated,” said Professor Bruford.

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In July scientists announced they had produced the first hybrid embryos ready to place in mothers, while southern white rhinos in zoos have been suggested as viable surrogates.

Once they have obtained permission to use eggs from the last remaining northern whites, the next step will be to create pure-breed embryos using them.

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