Tag Archives: de-extinction

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

De-Extinction: Bring Back the Passenger Pigeon

The Crispr-Cas9 system consists of two main parts: an RNA guide, which scientists program to target specific locations on a genome, and the Cas9 protein, which acts as molecular scissors. The cuts trigger repairs, allowing scientists to edit DNA in the process. Think of Crispr as a cut-and-paste tool that can add or delete genetic information. Crispr can also edit the DNA of sperm, eggs and embryos—implementing changes that will be passed down to future generations. Proponents say it offers unprecedented power to direct the evolution of species.

The technology is widely used in animals. Crispr has produced disease-resistant chickens and hornless dairy cattle. Scientists around the world routinely edit the genes in mice for research, adding mutations for human diseases such as autism and Alzheimer’s in a search of possible cures. Crispr-edited pigs contain kidneys that scientists hope to test as transplants in humans.  Crispr has been discussed as a de-extinction tool since its earliest days. In March 2013 the conservation group Revive & Restore co-organized the first TedXDeExtinction conference in Washington, D.C. Revive & Restore was co-founded by Stewart Brand, the creator of the counterculture Whole Earth Catalog and a vocal advocate for a passenger pigeon revival.

The last known passenger pigeon—a bird named Martha—died in captivity at a Cincinnati zoo in 1914….The first step was to sequence the passenger pigeon genome…Sequencing an extinct species’ genome is no easy task. When an organism dies, the DNA in its cells begins to degrade, leaving scientists with what Shapiro describes as “a soup of trillions of tiny fragments” that require reassembly. For the passenger pigeon project, Shapiro and her team took tissue samples from the toe pads of stuffed birds in museum collections. DNA in the dead tissue left them with tantalizing clues but an incomplete picture. To fill in the gaps, they sequenced the genome of the band-tailed pigeon, the passenger pigeon’s closest living relative.

By comparing the genomes of the two birds, researchers began to understand which traits distinguished the passenger pigeon. In a paper published last year in “Science,” they reported finding 32 genes that made the species unique. Some of these allowed the birds to withstand stress and disease, essential traits for a species that lived in large flocks. They found no genes that might have led to extinction. “Passenger pigeons went extinct because people hunted them to death,” Shapiro says

.Revived passenger pigeons could also face re-extinction. The species thrived in the years before European settlement of North America, when vast forests supported billions of birds. Those forests have since been replaced by cities and farmland. “The habitat the passenger pigeons need to survive is also extinct,” Shapiro says.  But what does it mean to bring an extinct species back? Andre E.R. Soares, a scientist who helped sequence the passenger pigeon genome, says most people will accept a lookalike as proof of de-extinction. “If it looks like a passenger pigeon and flies like a passenger pigeon, if it has the same shape and color, they will consider it a passenger pigeon,” Soares says.

Shapiro says that’s not enough. Eventually, she says, gene-editing tools may be able to create a genetic copy of an extinct species, “but that doesn’t mean you are going to end up with an animal that behaves like a passenger pigeon or a woolly mammoth.” We can understand the nature of an extinct species through its genome, but nurture is another matter. 

After he determines how passenger pigeon DNA manifests in the rock pigeons, Novak hopes to edit the band-tailed pigeon, the passenger pigeon’s closest living relative, with as many of the extinct bird’s defining traits as possible. Eventually, he says, he’ll have a hybrid creature that looks and acts like a passenger pigeon (albeit with no parental training) but still contains band-tailed pigeon DNA. These new-old birds will need a name, which their human creator has already chosen: Patagioenas neoectopistes, or “new wandering pigeon of America.”

Excerpts from Amy Dockser Marcus, Meet the Scientists Bringing Extinct Species Back From the Dead, WSJ, the Future of Everything, Oct. 11, 2018

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