It’s tricky with birds, we are told:
While efforts are underway to bring back extinct mammals, such as the woolly mammoth and quagga, through cloning, artificial insemination, and a breeding process that aims to revert domesticated species to phenotypes that closely resemble their wild ancestors, birds’ reproductive systems are not as amenable to these techniques.
So scientists are turning to cultured germ cell transmission, a promising technique that has been used to propagate gene-edited domesticated chickens for more than a decade. The idea is that genes from extinct birds could be replicated and introduced into host embryos’ germlines.
While the technique works well in chickens, current cell culture media do not support wild bird primordial germ cells (PGCs), the precursors to sperm and egg. PGCs ferry genetic sequences into a host so they can be passed down through generations. Revive & Restore, an organization weaving biotechnologies into wildlife conservation and backing much of the research into de-extinction, has made it a priority to develop such media. It would enable the large-scale amplification of wild bird PGCs, perhaps including those of endangered birds, and offer a platform for gene modification that could help return extinct species to life.W. S. Roberts, “The Booming Call of De-extinction” at The Scientist
Here are some of the real-life challenges that must be faced when, for example, reintroducing the Tasmanian devil to Australia:
Earlier this month, an environmental organization announced it had released 26 Tasmanian devils (Sarcophilus harrisii) into a sanctuary north of Sydney as part of a project to reintroduce the species to the Australian mainland, where it has not existed in the wild for about 3,000 years …
[conservation biologist] John Ewen: This is one of the one of many tricky challenges when it comes to conservation translocation. When a species is lost from a system, something’s gone wrong, and oftentimes, we’re not entirely clear what exactly were the key drivers of the past extinction. Compounding that, the longer the time it’s been since that extinction event and when you’re trying to put the species back, a whole bunch of other things in that ecosystem could also have changed. And so there’s this significant challenge of uncertainty and very complex ecosystems that we’re working within. You have to confront that and try and make the best decisions that you possibly can.
I think that systems like the Australian mainland have changed a lot in 3,000 years. And I’m not sure that we’ve got a complete understanding of what caused the Tasmanian devils to be lost in the first place. . .Shawna Williams, “How to Reintroduce a Long-Lost Species” at The Scientist
The interesting part will be to see whether—if both the animals and the environment have changed—reintroduction or recreation from advanced genomic techniques produces a viable independent species or a species that humans must indefinitely maintain.