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NThe world’s two last surviving northern white rhinos, Ajin and his daughter Fatu, live in an evolutionary twilight zone. This is the last living evidence of a functionally extinct lineage that dates back millions of years.
But this week, scientists moved one step closer to bringing the species back from oblivion by successfully implanting the first embryo in a relative of the white rhinoceros.
The ultimate goal of restoring an entire herd of northern white rhinos using frozen egg, sperm, and embryo banks and gene-editing techniques may sound like the arrogant artifice of a scientist trying to play God. But the team behind this project and others believe that in vitro fertilization and other assisted reproductive technologies (ART) could transform conservation efforts for some species and mitigate the devastating effects of climate change and habitat loss. It says that there is a sex.
“Scientists can offer to undo some of the dramatic mistakes that humans have made,” said Professor Thomas Hildebrandt of the Leibniz Institute for Zoo and Wildlife Research in Berlin, who is working on the Rhino BioRescue Institute. Responsible for the project. “We are not playing God. We try to preserve what God created. All we bring back is what is on this earth and has been destroyed by humans.”
Hildebrandt sees this technology as a last insurance policy for “cornerstone” species such as the northern white rhino, whose loss would have cascading ramifications throughout the ecosystem. But for many species, efforts are underway long before the species reaches such apocalyptic levels.
“I’ve worked with giant pandas, great apes and elephants,” Hildebrandt said. His team has previously coordinated the collection of semen from wild elephants to improve the genetic diversity of zoo populations. The actual challenges can be quite large. A helicopter must be used to immobilize the elephant and electroejaculation must be used to extract the sperm. In rhinos, the ovaries are located about 2 meters deep in the abdomen, so ovary collection and embryo transfer are done through the rectum. “We’re dealing with an animal that weighs 2.2 tonnes,” Hildebrandt said.
According to Dr Andres Gambini from the University of Queensland, adapting IVF protocols developed for commercial livestock is not always easy. He is developing in vitro fertilization technology for endangered Somali wild donkeys and koalas.
“We thought this horse was very similar to a donkey, so we did the same thing and it didn’t work,” he said. “They have a different ecology.”
Although the research is still ongoing, he could help preserve the genes of populations living today. “We may not be able to transfer embryos tomorrow or use those samples today, but we know we can use them in the future,” he said. “It’s a must for us.”
Dr. Jennifer Barfield, a veterinary scientist at Colorado State University, is using in vitro fertilization to protect bison in Yellowstone National Park. The herd is susceptible to brucellosis, a bacterial disease that can cause miscarriages and infertility, but in vitro fertilization can produce healthy embryos that can be transferred to disease-free surrogate mothers.
“These techniques are also used to move valuable genetics between populations in the form of sperm, eggs and embryos, which is in many ways easier than moving live animals.” said Barfield.
Genetic diversity can become a problem long before a species reaches a critical mass. Habitat loss can fragment a species into isolated parts of its territory, which can cause genetic bottlenecks and inbreeding. ART acts as a genetic bridge between small at-risk populations.
In vitro fertilization and artificial insemination are used in zoos as an alternative to transporting potential mates around the world when pairs of animals fail to breed or when introduction into captivity could pose a risk. This is happening more and more often.
“Many animals choose their mates, but in captive breeding they often don’t have the ability to choose their mates,” said Professor Simon Girling, director of veterinary medicine at the Royal Zoological Society of Scotland, who supervised the pandas. Tian Tian and Yan Guan failed to conceive during their 10-year stay at Edinburgh Zoo.
“When we each had one, and when both of us didn’t work out, we didn’t have a chance,” Girling said. In the absence of romantic opportunities, in vitro fertilization was attempted, and Tian Tian had at least four chemical pregnancies, none of which resulted in implantation. The reason is not yet clear.
“Some prominent scientists came and wrote a report and we implemented all the recommendations. We had bamboo sent from China,” said Girling, adding that some other zoos He added that good results were obtained for pandas.
Hildebrand points out that IVF does not solve the problem of species loss, and that seeds are more than just genes. “We are under time pressure to produce the first calf to protect our heritage,” he says. “Living animals speak languages and know how to behave like northern white rhinos. We need to respect the complete package. We want animals in the wild, not zoo exhibits. It is a suitable ungulate.”
“We need to dramatically change our relationship with nature,” he added. “We find that the younger generation has a much better attitude about this.”
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