May 26, 2018
Cloning The Northern White Rhino: Scientists Find Genetic Material To Revive The Nearly Extinct Species

The northern white rhinoceros (NWR) is facing imminent extinction, after the last remaining male of the subspecies, Sudan (pictured above), died in captivity on March 20.

With no other northern white rhinos roaming in the wild and just two females left in captivity at the Ol Pejeta Conservancy in Kenya, the subspecies seems to be utterly doomed.

But researchers at the San Diego Zoo Institute for Conservation Research believe these rhinos could be given a second chance with cloning and the right advances in artificial insemination, the New York Times reports.

The scientists have found a way to bring back the northern white rhino with the help of cryopreserved genetic material — frozen cells stored in the zoo's collection of preserved samples, dubbed the Frozen Zoo.

According to a study published this week in the journal Genome Research, the samples currently found in the cryopreserved cells bank hold enough genetic diversity to see the northern white rhinos be reborn.

The team sequenced the DNA of nine cryopreserved cell lines belonging to northern white rhinos and compared them with southern white rhinoceros (SWR) samples, ScienceDaily reports.

The analysis uncovered that the two white rhino subspecies are more related than previously thought — they were initially considered distinct species, notes the New York Times — and that they diverged into separate populations some 80,000 years ago, each retaining high levels of genetic variation.

This means that southern white rhinos, which underwent a fantastic recovery over the last century, could be used as surrogates to revive their almost extinct cousins.

The team points out that northern white rhino embryos could be artificially implanted into the subspecies' closest relative, ushering in a new dawn for the nearly doomed rhinos.

"The SWR went through a severe genetic bottleneck but is now the most populous of all forms of rhino at approximately 20,000 individuals, suggesting that a genetic rescue utilizing these cell lines could be the foundation for a similar recovery in the NWR," said study lead author Tate Tunstall.

Dr. Oliver Ryder, research co-author and the director of conservation genetics at San Diego Zoo Global, points out that genetic recovery methods could give northern white rhinos a fighting chance against their looming extinction.

"If it came down to the materials in the Frozen Zoo, we could turn those cells into animals."
The researchers explain that similar methods based on advanced sequencing technology, cryopreservation, and novel reproductive strategies could help save other critically endangered species as well.

"Our study demonstrates the emerging role for whole-genome-sequencing analysis to evaluate the potential for population recovery," says Cynthia Steiner, who directed the San Diego Zoo study.

Nevertheless, not all scientists agree that we should interfere with the laws of nature just because we have the means to do it.

While Joseph Bennett, a conservation researcher at Carleton University in Ontario, believes that bringing back the northern white rhino could be a "really nice 'good news story' for people" and much easier to achieve than the ongoing project to resurrect the woolly the mammoth, other scientists disagree.

Among their reasons, the New York Times cites the concern that the pouring money into projects aimed at resurrecting functionally extinct creatures cuts back the funding, and thereby the chances of survival, for other endangered species that are more likely to make a swift recovery.

In addition, some voices argue that the resurrected animals would probably be confined to living in captivity, perhaps never roaming in the wild like their predecessors, and could potentially be affected by harmful mutations.

Jason Gilchrist, an ecologist at Edinburgh Napier University in Scotland, says that conservation efforts should focus on returning animals to their native way of life, something that would be questionable in the case of the revived northern white rhinos.

"As an ecologist, what I want is to see wild ecosystems functioning as close to naturally as they can."