Pregnant southern white rhino raises hopes northern white rhino can be saved

Ultrasound image. Southern White Rhino at San Diego Zoo Safari Park pregnant through artificial insemination. Picture credit: San Diego ZOONOOZ
21 May 2018

BONN, Germany (Landscape News) — A southern white rhino named Victoria has been successfully impregnated through artificial insemination with sperm from a male counterpart, raising hopes that preservation of the northern white rhino is possible, according to an announcement last week by researchers at the San Diego Zoo Institute for Conservation Research.

In March, Sudan, the last known male northern white rhino died in captivity, leaving only two remaining female survivors. The only prospect for conservation of the distant subspecies of the southern white rhino now lies in artificial insemination, scientists say.

Researchers are optimistic that through artificial insemination, in vitro fertilization and embryo transfer, southern white rhinos could potentially serve as surrogates to carry northern white rhino embryos, according to the statement released several days before the International Day for Biological Diversity on March 22.

“The confirmation of this pregnancy through artificial insemination represents an historic event for our organization but also a critical step in our effort to save the northern white rhino,” said Barbara Durrant, director of reproductive sciences at the San Diego zoo institute.

“The sperm had excellent motility and the procedure went very well – we are excited to confirm a pregnancy has occurred but we have a long time before we can declare a real success with the birth of a healthy southern white rhino baby.”

If Victoria carries the southern white rhino calf to term, it will be born in summer 2019.

Despite the inevitable challenges that lie ahead, researchers are optimistic that a northern white rhino calf could be born within 10 to 15 years, the statement said. The procedure could also be applied to other rhino species, including critically endangered Sumatran and Javan rhinos.

To successfully produce a northern white rhino, multiple steps must be achieved. The genome of the northern white rhino must be sequenced to clarify the extent of genetic divergence from its closest relative, the southern white rhino.

Another step requires conversion of cells preserved from 12 individual northern white rhinos in the San Diego Zoo Institute into stem cells that could develop into sperm and eggs—a process successfully begun in the the Scripps Research Institute laboratory with results published in 2011, the statement said.

SPECIES AT RISK

The white rhino (Ceratotherium simum) comprises two subspecies: the northern white rhino (Ceratotherium simum cottoni) and the southern white rhinocerous (Ceratotherium simum simum). The latter was nearly extinct in the 19th century, but conservation efforts succeeded and, according to the last published estimates from the International Union for Conservation of Nature (IUCN), by 2012 there were over 20,000 of them.

For the northern white rhino –which once roamed Central African Republic, Chad, Democratic Republic of Congo, Kenya, South Sudan and Uganda — things have been different.

In the 1960s their population was around 2,300, but poaching and civil wars substantially reduced their number in the 1980s. After 20 years of hard conservation work, in 2003 the population was at about 30, according to IUCN. But once again, extreme poaching reduced the population to just four three years later.

When Sudan was euthanized by his Kenyan caretakers on March 19, he was 45 years old and his health had deteriorated after a series of age-related complications worsened.

A report from the Kenyan conservancy where he died states that Najin and Fatu, the last two surviving females, cannot reproduce; one is sterile and the other has not been able to carry a calf to full term.

Signs of the northern white rhino were last seen in 2007 in the wild, IUCN reports. It is now considered extinct in the wild.

Between 1948 and the mid-1970s, there were 22 northern white rhinos in captivity and despite efforts to reproduce them, by 2000 there were only three alive including Sudan, his daughter Najin and his granddaughter Fatu, according to a 2016 report in Zoo Biology journal.

The loss of Sudan is a reminder of the dire situation other rhino species face.

Rhino horns have been an important part of traditional Chinese medicine for centuries and more recently, an upsurge in their demand has been linked to their popularity in Vietnam as a “party drug” and as a cure for cancer.

China, a signatory to Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), banned the rhino horn trade and Vietnam has voiced its determination to stop the exploitation of elephant ivory and rhino horns. However, the trade has continued, reports show.

FIGHTING BACK

Not surprisingly, the last images of Sudan show him heavily guarded at Ol Pejeta Conservancy in Kenya, his refuge during his final years and where Najin and Fatu still live.

Ol Pejeta Conservancy and Dvůr Králové Zoo in the Czech Republic (which was once Sudan´s home) are trying to raise $9 million to save the northern white rhino. Every passing day the species grows closer to extinction, despite the many years of international joint efforts to save it.

As part of those efforts, a group of scientists met in December 2015 in Vienna to formulate a road map that could bring the northern white rhino back from the brink. According to the scientists, if their proposed plan goes well northern white rhino offspring could appear within a decade or so. But they project it would require at least 50 years “for the NWR population to grow out of its current critically endangered status.”

The journey will be long and difficult, requiring the optimization of several in vitro fertilization techniques and stem cell technology procedures along the way, according to the report, which also states that several of these procedures would require a steep learning process and an appropriate ethical surveillance to ensure that other species are not subjected to strenuous medical procedures in the name of northern white rhino survival.

Embarking on a journey like this means facing up to other ethical challenges.

Conservation resources are limited as there will always be competition for scarce funds between species and between species and ecosystems.

Additionally, the dilemma of whether we should mend the wrongs of the past or prevent future extinctions will always arise, even if help is provided by private donors or institutional grants like the funds managed by Revive and Restore, an initiative that aims to rescue extinct and endangered species.

But even if a viable northern white rhino population is attained, involvement from a variety of stakeholders would be required to restore rhino habitat and ensure the protection of the future northern white rhino population.

This is easier said than done. Social conflicts within the northern white rhino habitat area and the involvement of criminal syndicates in the rhino horn trade have made their protection more difficult. Also, innovative approaches might be needed to eliminate or significantly reduce the illegal trade.

Whatever happens, it is becoming clearer that humans are accelerating the extinction of a variety of species due to overexploitation, land use change and/or habitat loss in what has been called the earth’s sixth mass extinction–and the first due to human activities.

The northern white rhino is at a crossroads. If we want to restore a self-sustaining population there is a long, but not impossible, way ahead.