With only two living females, the Northern white rhino is functionally extinct. Now, scientists are attempting to use assisted reproductive technology to save itby Philip Ball / July 5, 2018 / Leave a comment
The Northern white rhinoceros of the grasslands and savannah of southern Africa has been hunted to extinction. But modern assisted reproduction technology might yet rescue it.
That’s according to a new study which demonstrates a dramatic possibility for developments in embryology to transform nature conservation.
The population of Northern white rhinos has been tiny since the 1980s, rarely exceeding 30 or so.
Currently, there are just two alive. Both were born in captivity and belong to the Dvůr Králové Zoo in the Czech Republic but are kept under armed guard in the Ol Pejata Conservancy of Kenya.
Both, however, are females—a mother and daughter The last surviving male died of natural causes in March. So there is no way, now, for the species to persist by natural means; it is “functionally” extinct.
The reason for that is poaching. Rhino horn fetches huge prices on the black market, and conservators have been taking to sawing off the horns of rhinos under sedation to eliminate poachers’ key motivation.
To Jan Stejskal of the Dvůr Králové Zoo, the plight of the Northern white rhino is “a symbol of the human disregard for nature.”
To make matters worse, it’s rare for the rhinos to reproduce in captivity—which is why the Czech animals were originally returned to the wild.
Faced with this dire situation, in 2015 scientists at Berlin’s Leibniz Institute for Zoo and Wildlife Research, in collaboration with others, hatched a plan to maintain the endangered rhinos using reproductive technology.
The rhinos’ DNA was sampled and stored in gene banks, and the researchers decided to try to create rhino embryos using egg cells (oocytes) from the surviving females. Sperm had been taken, and frozen, from males of the species when they still survived.
This is, basically, emergency IVF—with scant and imperfect materials. With just two remaining females, the options both for collecting oocytes and gestating any embryos are severely limited. But there are alternatives.
One is cloning. This involves transferring the genetic material from an animal’s fully developed tissue cells into an oocyte that has been emptied of its own chromosomes, and then stimulating the egg to grow into an embryo by artificial means.
That’s how Dolly the Sheep was created in 1997, using chromosomes taken from the mammary cells of an adult ewe.
In this case, oocytes could be taken…