Tag Archives: extinction

De-Extinction: Horse Revival


A little baby horse named Kurt is a symbol of renewed hope for the survival of his kind. Born on 6 August 2020, he is the world’s first ever successfully cloned Przewalski’s horse, an endangered wild horse native to the steppes of central Asia. What makes Kurt even more exciting is that he was cloned from genetic material cryopreserved 40 years ago – reviving genetic diversity thought to have been lost decades ago…

Przewalski’s horses roaming the steppes declined dramatically after World War II, due to a combination of factors such as hunting, competition with livestock as humans moved into their territory, and severe winters. The last confirmed sighting of a Przewalski’s horse in the wild was in 1969. Luckily, some of the horses still remained in zoos. But not many. A total of 12 horses made up the ancestors of a captive breeding program – 11 Przewalski’s horses wild-caught between 1899 and 1902, and another caught in 1947. Thanks to this breeding program, there are around 2,000 individuals today. That’s incredibly impressive, but the growing population isn’t without problems.

Those 12 ancestor individuals represent what is known as a population bottleneck – when a species undergoes a severe reduction in numbers. From that point, a population can recover, but it can also be the beginning of the end. One of the reasons for that is lower genetic diversity. With less variation, a population is less able to adapt to potential stressors or changes to their environment…

Enter a Przewalski’s horse named Kuporovic, who lived from 1975 to 1998. An analysis of the captive breeding pedigree revealed that Kuporovic’s genome had unique ancestry from two wild founders. This meant he offered significantly more genetic variation than any of his living relatives, so in 1980, scientists took a sample and preserved it in San Diego Zoo’s Frozen Zoo.  San Diego Zoo partnered with wildlife conservation group Revive & Restore and pet cloning company ViaGen Equine to create an embryo using Kuporovic’s genetic material. This embryo was implanted in a domestic horse (Equus ferus caballus) surrogate, and was born healthy after a normal pregnancy.

Excerpt from Scientists Clone an Endangered Przewalski’s Horse For The First Time, Science Alert, Sept 7, 2020

What You Can Do with $1 Million: Saving the New Zealand Parrot

Scientists in New Zealand have genetically sequenced every adult kakapo.  The kakapo, a cuddly bird that lives in New Zealand, is not designed for survival. Weighing up to 4kg, it is the world’s fattest and least flighty parrot. It mates only when the rimu tree is in fruit, which happens every few years.  It evolved in the absence of land-based predators, so instead of soaring above the trees it waddles haplessly across the dry forest floor below. When it stumbles across something that might kill it, it has the lamentable habit of standing still….Such oddities turned the kakapo into fast food for human settlers—and for the cats, rats and possums they brought with them. It seemed extinct by the 1970s, until scientists stumbled on two undiscovered populations in the country’s south. These survivors were eventually moved to small predator-free islands, where the Department of Conservation has spent decades trying to get them to breed…Its patience may finally be rewarded. The rimu was in fruit this year, and more than 80 chicks hatched after a bumper crop, making this the best breeding season on record. Many have survived into adolescence, increasing the number of adult kakapos by a third, to 200 birds.

But another threat to the kakapo is a lack of genetic diversity, because of low numbers and inbreeding. This is one reason why fewer than half of kakapo eggs hatch. By sequencing the genome of every living bird, scientists can identify closely related individuals and prevent more inbreeding by putting them on different islands. Well-matched birds cannot be forced to mate, but artificial insemination is also proving effective. Every bird is fitted with a transmitter to track its slightest movement. If a female mates with an “unsuitable” male, the process can be “overridden” with another bird’s semen. Time is of the essence, so drones are being used to whizz kakapo sperm to the right place.

All these efforts cost almost nz$2m ($1.3m) this breeding season. Yet the kakapo’s future still looks precarious. Earlier this year a fungal disease tore through the population. And tiny as the number of kakapos is, space is running out on the two islands where most of them live. New predator-free havens must soon be found. 

Excerpts from How eugenics is saving a pudgy parrot, Economist, Aug. 31, 2019

Fixing the Earth: De-Extinction

Is extinction forever? Efforts are under way to use gene editing and other tools of biotechnology to “recreate” extinct species such as the woolly mammoth and the passenger pigeon. Could such “de-extinction” initiatives aid conservation by reviving species lost to habitat destruction and climate change?…. These are some of the questions addressed in Recreating the Wild: De-extinction, Technology, and the Ethics of Conservation, a new special report of the Hastings Center Report.

Advances in biology have revealed the ways the environment influences species’ genomes. Even if scientists could produce creatures with DNA identical to that of extinct species, different environmental pressures would alter their genomes in novel ways, raising the possibility that those creatures would differ from the extinct species…

Many scientists believe that although the maintenance of biodiversity benefits ecosystems, changes to the environment could make the reintroduction of extinct species difficult—possibly even ecologically disruptive. …Several commentators in the report raise the concern that the notion that extinct species might be “brought back” could weaken efforts to prevent extinctions. “By proposing that we can revive species through modern technology, we give the impression that species are ‘throwaway’ items,” write Robert DeSalle, a curator at the American Museum of Natural History’s Sackler Institute for Comparative Genomics, and George Amato, director of the conservation genomics program at the institute.

Excerpt from Recreating the wild: De-extinction, technology, and the ethics of conservation, https://phys.org/news/, Aug. 2017