A pair of southern white rhinos named Victoria and Amani at the San Diego Zoo Safari Park are expecting, and while any pregnancy is reason to celebrate, these have the potential to save an animal essentially poached out of existence.
If their pregnancies through artificial insemination are successful, it could be a significant step in helping the northern white rhino recover.
Only two northern white rhinos, a distant subspecies, are alive; both are female but they cannot bear a calf. The last northern white male rhino, named Sudan, was euthanized in March at a preserve in Kenya due to age-related health problems.
Researchers hope that one day Victoria and Amani could serve as a surrogate mothers, giving birth to a northern white rhino baby. They're optimistic that a northern white calf could be born this way within 10 to 15 years, and the work could also be applied to other rhino species, including critically endangered Sumatran and Javan rhinos.
"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, Ph.D., director of reproductive sciences at the San Diego Zoo Institute for Conservation Research.
Victoria and Amani are two of six female southern white rhinos relocated to the San Diego park from private reserves in South Africa. The San Diego Zoo Institute for Conservation Research is conducting tests on all of them to see if they would be successful as surrogate mothers.
Seven-year-old Victoria was the first to become pregnant in July, and 10-year-old Amani became pregnant in September. Researchers will be watching them closely to see if they will successfully carry their calves through the gestation period, which typically lasts 16 to 18 months.
The zoo institute has the cells of 12 individual northern white rhinos stored at its "Frozen Zoo." Scientists hope to convert those preserved cells to stem cells, which could develop into sperm and eggs to be used to artificially inseminate the female southern white rhinos.
A breakthrough with embryos
A couple months after the announcement of Victoria's pregnancy, a team of international scientists announced the successful creation of embryos from the sperm of deceased northern white rhinos and the eggs of southern white rhinos. They used electrical pulses to stimulate the sperm and egg to fuse together. After this success, the hope is that they can extract eggs from the last two surviving northern white rhinos — who are currently living in a Kenyan national park under 24-hour guard.
A new study offers hope that artificial insemination will be successful in the future. Researchers analyzed DNA from living southern white rhinos and compared it to DNA from museum specimens of northern white rhinos. They discovered the two sub-species are more closely related than previously thought and cross-bred for thousands of years after the species split into two.
"Everyone believed there was no hope for this sub-species," said professor Thomas Hildebrandt, from the Leibniz Institute for Zoo and Wildlife Research in Berlin, told BBC News. "But with our knowledge now, we are very confident that this will work with northern white rhino eggs and that we will be able to produce a viable population."
Editor's note: This article has been updated since it was originally published in May 2018.
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