Mike McKenney <\/p>\n
The last male northern white rhino has seen better days. At the advanced age of 43, arthritic in leg and blind in one eye, Sudan struggles to get around. Since he now finds other rhinos intolerable, he has his enclosure at the Ol Petja Conservancy in Kenya all to himself. On occasion he welcomes human presence he is partial to a hind leg scratch, in particular but like other crotchety males he would sometimes rather not be disturbed, shaking his head and snorting to make his displeasure known. <\/p>\n
Conservation is a discipline driven by crisis and perhaps nothing illustrates this better than the northern white rhino. Before they were poached near out of existence, northern whites roamed central and eastern Africa. As recently as the 1960s there were 2,300 in the wild. Today just three individuals remain: Sudan, his daughter and granddaughter, all at Ol Petja. Neither female can carry a calf to term. With a limited gene pool and the prospect of natural reproduction extinguished, the subspecies is considered functionally extinct. <\/p>\n
In this moment of climactic disruption, poaching and urban expansion, species are lost all the time, of course. Since 1900 about 70 mammals are believed to have gone extinct, along with some 400 other types of vertebrate. Perhaps due to the abject hopelessness of their situation, northern whites are at the centre of a daring effort to arrest what seems inevitable: to bring them back from the brink. <\/p>\n
The plan is two-pronged. First, a team of scientists at the Leibniz Institute for Zoo and Wildlife Research in Germany, along with international specialists, are attempting to grow a northern white embryo in-vitro, using oocytes, or eggs, from the two living females and frozen sperm. Once the embryo reaches the relatively stable blastocyst stage, it will be implanted in a surrogate southern white rhino, a sister subspecies, who will carry the northern white calf to term. So far the team has reached the zygote stage of embryonic development; next is the blastocyst. Thomas Hildebrandt, head of reproduction management at the Leibniz institute, says he is quite confident that the goal will be achieved soon. <\/p>\n
Yet for a new generation of northern white rhinos to thrive, its gene pool must be diversified. We have an active population of three and they are all related to each other, so you never can produce a viable self-sustaining population out of these three, says Hildebrandt. That would make no sense at all. <\/p>\n
So, for step two of the scheme, Hildebrandt is collaborating with Katsuhiko Hayashi, a reproductive biologist at Kyushu University in Fukuoka, Japan. Their aim is to transform skin cells from the living animals and from tissue samples kept in cryonic storage into stem cells. These cells, called induced pluripotent stem cells (iPS), have the capacity to develop into any type of tissue, including eggs and sperm, which could be used to produce gametes. Though difficult, this objective might not be far off in real terms. In 2011, a team at the Scripps Research Institute in La Jolla, California, created iPS cells from the younger female rhinos skin. In October, Hayashis team in Japan transformed mouse skin cells into eggs in-vitro and then used those eggs to birth healthy pups, a scientific first. <\/p>\n
Although, in theory, this technique could be applied to other critically endangered mammals, Hildebrandt doesnt think this cellular-based approach to conservation should be routine. It requires a lot of resources, he says. But mankind is responsible for the dramatic situation of the northern white rhinos and with the knowledge we have in our hand we might be capable, and Im fairly confident we are, of saving the species, of not losing them. <\/p>\n
Some are sceptical about whether this radical intervention is worthwhile. Not only does it carry the implicit message that it is okay to drive a species to extinction, since it can always be reversed, it fails to redress the conditions that decimated the species in the first place. To truly wrest a species from extinction we need to provide and protect the habitat in which it lives. Hildebrandts scheme is also expensive; he estimates it will cost $5m to produce a northern white rhino calf, though his team currently operates on a yearly budget of 40,000, plus about 60,000 for equipment. <\/p>\n
What are we moving towards, some sort of virtual conservation? says Michael Knight, chair of the International Union for Conservation of Natures African Rhino Specialist Group. If you want to make the best contribution to conserve rhinos in Africa, we should be securing the landscape and making sure those 25,000 [southern white] rhinos on the landscape are breeding as fast as they possibly can. <\/p>\n
Knight advocates pursuing a fall-back policy crossbreeding the northern white rhino with its southern cousin. The southern white is a conservation success story. Once thought to be extinct, in 1895 a population of fewer than 100 individuals was discovered in Kwazulu-Natal, South Africa. Through traditional conservation mechanisms, that population has now bloomed to some 25,000 rhinos. Crossbreeding will preserve at least some of the genetic traits unique to the northern white. Knight calls it hedging our bets. <\/p>\n
This move seems sensible. Yet the effort to rewind the extinction process is not about saving the northern white rhino alone. Its decline is a symptom of the broader loss of biodiversity worldwide. Biologists have found that the Earth is currently losing mammal species 20 to 100 times the rate of the past, and there is a growing consensus in the scientific community that we are on the brink of the sixth mass extinction the last such event took out the dinosaurs. If climate change is the largest collective-action problem humankind has faced, preserving biodiversity requires all hands on deck. <\/p>\n
I dont think one should look at it as saving a species, says Richard Vigne, chief executive office, Ol Petja Conservancy. Theres lots of arguments about whether [northern whites] are a separate species or a subspecies, or whatever, but frankly it doesnt matter that much. <\/p>\n
What is important, he says, is protecting a rhino with the specific genetic traits, evolved over millions of years, that enables it to inhabit central Africa. \"We don't know what the situation will be like in central Africa in 4,000 years,\" says Vigne. \"National parks may want to bring rhinos back. We need to retain the opportunity to do that.\" <\/p>\n
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