Genetic Rescue Is Huge For De-Extinction, But Not For The Reasons You Think

By November 3, 2020November 12th, 2020Uncategorized

This post was written by James Osborne, on his blog, A Mammoth Task.

On August 6th, 2020, a male foal called Kurt was born at the San Diego Zoo. Kurt is a Przewalski’s horse, and he is a clone. The once desperately endangered subspecies of horse – spectacularly recorded by the artists of the palaeolithic – has been under the looming threat of extinction since it was first scientifically categorised in the 19th century. In the 1960s the subspecies became extinct in the wild as the last of its dwindling population was confined to breeding programmes in captivity.

The worry of conservationists was not that there weren’t enough individuals to prevent total extinction in the short term, but that the tiny captive population was in the midst of a genetic bottleneck – a problem that would only be made worse by inevitable inbreeding. The inbreeding resulted in lower levels of fertility, and the population continued to shrink.

Today, thanks to focused and coordinated population management programmes, Przewalski’s horses roam in the wild again. Populations can be found in Mongolia, China, and in the Chernobyl exclusion zone, as well as worldwide across zoos. However, the genetic diversity of the subspecies is still an area for concern for conservation scientists. Kurt was cloned from the cryogenically preserved cells of a Przewalski’s stallion that died in 1998, after pedigree analysis of the cells revealed an unmatched level of genetic diversity. When Kurt matures and starts to mate, he will – hopefully – contribute this rescued genetic diversity to the subspecies, helping to ensure the security of their uncertain future.

As animal populations continue to decline and genetic bottlenecks become more common, it seems that genetic rescue could have an important role to play in the future of many endangered species. Each individual that is cloned creates a blueprint for the future, with lessons to be learned from. When these clones are derived from cryogenically preserved cells, these blueprints become increasingly relevant for other cloning-based conservation programmes. As Dr Shapiro explains in her essay ‘Pathways to De-Extinction’, the most feasible route for future de-extinction programmes will likely make use of cloning in some form, and cryogenically preserved cells.

The prize for conservationists open to the positive potential of cloning for conservation benefit, isn’t necessarily the cloning of a member of an endangered species (though this can’t be under celebrated!), but that the principle has been successfully introduced to the public without controversy. Due to a cocktail of unfavourable media coverage, religious beliefs, and natural suspicion, the public is broadly sceptical of cloning and its associations. Often the first thing that comes to mind isn’t Dolly the sheep, but rumours of experiments in Chinese labs, associations with human cloning, and stem cell research.

De-extinction is already a controversial topic, and this is only exacerbated by links with cloning. So, un-controversially introducing the public to the idea that cloning can be used for conservation benefit is truly progress. As cloning based conservation programmes prove their utility, they create options that would otherwise be unworkable. They do not determine the future of conservation science; they simply ensure that a (hopefully never necessary) insurance policy is functional if called upon.

For more pictures and information on Kurt, visit www.reviverestore.org/p-horse