A new study may hold the key to saving the northern white rhino's rapid descent into extinction.
The world's last male northern white rhino died in March, bringing the subspecies dangerously closer to extinction with only two female members left worldwide and living at the Ole Pejeta Conservancy in Kenya.
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With the death of the male rhino, scientists have scrambled to find ways to save the subspecies. Now a new DNA study shows northern white rhinos have mated and exchanged genes with the southern white rhinos in the past, and this would be a viable option if other methods of using pure northern white rhino genetic material fail, said Michael Bruford of Cardiff University and co-author of the study.
The study published in the journal Proceedings of the Royal Society B has revealed that the two subspecies are closer than previously thought, Bruford said.
In vitro experiments conducted in the lab between northern white sperm and southern white egg showed promising results, he said.
"They are different but have had the ability to exchange genes in the past," Bruford said. "This happened during the ice ages when African grasslands expanded, bringing the two populations into contact."
He said the subspecies mixed as recently as 15,000 years ago.
If reproductive technologies involving only northern white rhino genes fail, Bruford said, scientists could consider using southern white females for in vitro fertilization. He said a hybrid female rhino lived in a zoo in the Czech Republic and survived for 32 years.
The southern white rhinos are not as endangered -- Ol Pejeta has 32 -- and while the offspring would not be 100% northern white rhino, it would be better than nothing, experts said.
Researchers saved some of the male rhino's genetic material in the hopes of using it for artificial insemination, Elodie Sampere, a representative for Ol Pejeta, has previously said.
Scientists have used IVF techniques to develop hybrid rhino embryos -- "test-tube rhinos."
A team was also able to extract stem cell lines from southern white rhino embryos, which could be used to make reproductive cells such as eggs and sperm to create embryos.
The Ol Pejeta Conservancy acquired northern white rhinos -- two males and two females -- in 2009 from a zoo in the Czech Republic. Both male northern white rhinos died, leaving the fate of the subspecies on the female rhinos.