The last male northern white rhinoceros, Sudan, has recently recovered from an age-related infection that almost took his life earlier this month. The scare has sparked a surge of talks on conservation and on the chances of Sudan’s subspecies surviving in the future.
Sudan is a celebrity of sorts, attracting thousands to his conservancy and being listed as “The Most Eligible Bachelor in the World” on the Tinder dating app last year in a fundraising effort.
Forty-five-year-old Sudan is one of three northern white rhinos left. The other two are his daughter, Najin, and his granddaughter, Fatu. They live under armed guard and 24-hour care in Ol Pejeta Conservancy in Kenya.
None of these rhinos can reproduce again. Sudan’s prospects do not have a bright future because of his sperm quality, which was last measured in 2014. In the March 13 Scientific American article titled “Northern White Rhinos are about to Die Out—Should We Save Them?” Jan Stejskal wrote that, “Regarding saving the subspecies, Sudan is already functionally obsolete.” Stejskal is the director of communications and international projects at Dvr Králové Zoo in the Czech Republic.
Najin, meanwhile, is too old to bear the weight of a mating male or to carry a pregnancy and Fatu has uterine issues. However, both Najin and Fatu still produce eggs. As such, their donor eggs can be used for in vitro fertilization, or IVF, with stored sperm from a deceased male. The fertilized egg can then be put into a southern white rhinoceros, a closely related subspecies. IVF is already used in the cattle industry to breed more robust herds, providing precedence for this process. The magazine article also noted that this zoo technically owns the three rhinos.
It is obvious that it is possible to save the subspecies, but the question becomes one of whether or not they should be saved.
Some organizations are against the idea of saving the northern white rhino, labeling the saving as a poor use of resources. One such organization, Save the Rhinos, arsuggests that saving the subspecies with IVF and surrogacy would be similar to reviving extinct woolly mammoths rather than saving an endangered species. The organization points out that it is better to allocate the money into poaching prevention and saving habitats, which could help living rhinos.
The organizations that back the idea of using IVF to save the three rhinos are not those that are concerned with rhino conservation, but those that have a stake in developing IVF technologies for other species, according to Stejskal.
Advancement in this area is slow. According to an article titled ‘A Race Against Time’: Scientists Hope to Save Northern White Rhino From Extinction” from NBC San Diego, experts from around the world met in Vienna in December 2015 to hash out a plan to save the northern white rhino. Then, in May 2016, the group issued its plan in the open-access journal Zoo Biology. The first step of the process involved extracting the eggs, which was difficult because the eggs of a rhino are stored 5 feet inside its body, and the egg follicle is a millimeter or two in diameter.
Progress was made since 2016. Ovaries were taken from Nabire, a northern white rhino who died in 2015. Although the eggs were old and in bad shape, they provided information about the rhinos and about how the fertilized embryo developed.
There are still concerns, however, that cannot be overlooked. There are only two sources of eggs: the two living female northern white rhinos This would result in offspring that lack genetic diversity. Therefore, another line of work, spearheaded by the San Diego Zoo Conservation Research, is dedicated to turning somatic rhino cells into sperm and egg cells. Body tissue was collected from an additional five rhinos. If this research is successful, then it could boost the size of the population to 12.
Despite all these setbacks, the research team and Stejskal are hopeful. While progress is slow, Najin and Fatu are likely to survive and continue producing eggs, meaning the research team can continue moving forward.
Editor’s Note: Sudan was put to sleep on Monday, March 19, after this article was written.