December 1, 2021

I, Science

The science magazine of Imperial College

Conservation has started to turn to more drastic measures to preserve endangered species ...


Despite conservation efforts, approximately 30% of all marine, fresh-water and land animals will become extinct in the next 50 years. In desperation, conservationists are turning towards the ‘Plan B’ approach of conserving animals outside of their natural habitat. But some of these methods are a bit more ambitious than a simple zoo: namely, the cryopreservation and cloning of endangered species.

Using cryopreservation, tissue samples from animals can be stored in liquid nitrogen (at −196 °C) for potentially hundreds of years, later to be thawed out and re-grown. Normal body cells can be stored safely and one day used to reproduce the animal via cloning. Several projects have already been established to start collecting samples of living animals before they become extinct. For example, the University of Nottingham, the Zoological Society of London and the Natural History Museum have been running their Frozen Ark Project since 1996.

Animal cloning uses a method called ‘somatic cell nuclear transfer’. A nucleus is extracted from a normal body cell (a ‘somatic’ cell) and transferred to an empty egg cell that has had its own nucleus removed. An electric current is then applied to make the nucleus and egg cell fuse together. If it is successful, and the egg begins to divide normally, the resulting embryo is then implanted into the uterus of a surrogate mother to continue developing.

As cloning only requires a body cell from the animal to be cloned, it is particularly useful when the egg or sperm cells of the animal are difficult to acquire. Just look at the movie Jurassic Park: scientists used blood cells to resurrect dinosaurs. So, by using cryopreservation and cloning, could we preserve cells from currently endangered animals and one day resurrect them even after they’ve gone extinct?

It has, in fact, already been done. In January 2009, a Pyrenean ibex was cloned from the preserved DNA of a skin sample taken before the last animal died in 2000. However this individual, the first animal to ever become ‘un-extinct’, only survived for seven minutes before dying of lung defects.

A major problem with the cloning approach is its dismally low success rate of only 6%. There can be many complications, such as early stage incompatibility of the nucleus and egg cell, complications in pregnancy or a long list of abnormalities in the clone due to incorrect gene expression.

But cloning technology is fast improving.

In November of 2012, Brazilian scientists announced they were preparing to clone eight endangered species, including black lion tamarin monkeys, collared anteaters and jaguars. And in December 2011 a research team declared they were hoping to clone a woolly mammoth within five years, using a well-preserved sample of bone marrow and an African elephant as a surrogate mother.

However, many conservationists dislike the idea of relying on cloning to save endangered species, and insist that all efforts must primarily be focused on habitat conservation: after all, what use is being able to clone an animal if its natural habitat is gone? These cloned animals will not be adapted to live in the new environment. In addition, a population of clones originating from only a few individuals would be genetically weak, and with no parents to teach them their natural behaviour they might not survive at all. So while it may be possible, cloned animals would only really hold aesthetic value. Surviving in zoos as nothing more than exhibits, rather than repopulate the planet, they would simply remind us of the awful job we had done at sustaining the biodiversity of our planet.