When in 1914 at the Cincinnati zoo died the passenger pigeon Martha, began the end of a great era. Once the dominant species in Eastern North America, the passenger pigeon was a forest inhabited by huge flocks, up to several billions of individuals for tens of thousands of years before you die completely. A huge number of these birds, combined with their diet based on seeds of trees, turned them into one of the most important engineers-ecologists of the time, forming the dynamics of the habitats, which relied on these forests. Now these ecosystems are losing biodiversity, says Ben Novak, lead researcher of Revive & Restore.
“When in 1914, this bird became extinct, held a dark force awakening industrial humanity, designed to destroy even the most abundant natural resources,” he says. So Novak, working with the California Institute, creates Revive & Restore — the program aimed at recovery of these species and the colonization of their natural habitats — with the usual pigeons and strength CRISPR.
Can we resurrect the dead?
Novak is part of a small group of engineers “definirane”, a relatively large group of scientists who hope to use genetic engineering to protect or revival of the iconic species of animals, destroyed by human activity.
For some definiranje (or extincti, de-extinxtion) — it’s a journey of atonement ecological scale. Yes, biodiversity is important, but who’s to say that an extinct species can adapt and survive in the ecological system that is constantly changing and has changed since his death? Or, more importantly, what if the resurrected animals — essentially, the “aliens” on Earth will do more harm than good to our fragile ecosystem?
“Why do we need this trouble”, asks the team of Novak. In the case of itinerant pigeons the answer is simple: recently, after almost a Millennium after the disappearance of people, we finally realized the crucial role they played in the formation of the Eastern North American ecosphere.
At the moment scientists have found that the passenger pigeon appeared more than 12 million years ago and were extremely adapted to life in dense flocks. New results, combined with the study of forest ecology, clearly show that these birds were the key engineers of the dynamics of the forest.
This Central role suggests that the passenger pigeon is much more important to the ecosystem than a simple attempt to succeed in resurrection of extinct species. “The return of the passenger pigeon will restore the regenerative cycles of forest dynamics, which need dozens of species that are reduced at the present time and trying to survive,” says Novak.
“The passenger pigeon is not just a model; it is perhaps the most important for future conservation of forest biodiversity in the Eastern part of America,” he says.
The two-step process: first, extinct species need to be resurrected from the dead. Secondly, you need to carefully evaluate the re-introduction of the species in the environment.
We have similar examples for the second step, explains Novak. Re-introduction of species to areas where they were eradicated, is a long-term science and scientists have already seen some success: the wolves in Yellowstone, elk in Kentucky, beavers in Scotland. The ultimate goal is to weigh the risks in order to do or not to do it: what will happen to the ecosystem if we stop to interfere.
In the case of the passenger pigeon is the result of his re-introduction is likely to be neutral — that is, it will become just another bird in the forest without any measurable impact or positive for the survival of other species.
In any case, the odds are in favor of Novak.
The first requirement is to bring the dead to life is a very new science. But thanks to a little tool called CRISPR, definiranje can take place.
Here’s the thing: unlike Jurassic Park, the scientists are not trying to revive an animal, based solely on his DNA.
The team approach uses the “find and replace”: let’s start with the usual dove, who rummaged through the trash in the city, and include genes characteristic of wandering pigeons. Use close relatives of pigeons with a striped tail. By selective withdrawal of the genes the animal has, the team hopes to concentrate once again on the genes in the offspring and thus promote “human surrogates” passenger pigeons at the genetic level.
When a sufficient number of generations, we can obtain interesting types of the artificial DNA is indistinguishable from extinct animals. But will a hybrid animal is the passenger pigeon, this is a philosophical question.
This strategy, which is shared by most of the bands trying to revive the animals. But the team Novak has the answer.
Compared to Dodo, for example, “there is usable DNA, because in the museums and collections of stuffed taxidermists taxidermy wandering pigeons more than any other bird,” says Novak. Add the fact that we have access to pigeons with a striped tail, and understanding their reproductive patterns, and get that “science of the resurrection could get all the right incentives and be persistent.”
Definiranje in practice
Since 2012, team Novak might have achieved greater success than any other project of definirane.
First, in a series of works and cooperation, the team gradually revealed the important influence that the passenger pigeon had on their ecosystems, and answered a longstanding question about how that number had dropped so quickly from billions to zero. Birds have evolved to adapt to life in a large population. Although they could probably to recover from low genetic diversity, human hunting drove the last nail in their coffin.
These studies together help the return of the passenger pigeon. Novak explained that in accordance with these results, we first must provide the pigeons with striped tails necessary mutations that will cause them to multiply as did the passenger pigeon, and they can live in dense communities. Then we should give the birds the necessary adaptation for effective existence in conditions of high social density, for example, features that will allow them to be more sensitive to social clues, or rapid maturation of offspring, so they devoted less time to raising children in large numbers.
The emergence of CRISPR changed everything. For the first time Novak and his team received access to relatively simple and low cost tool for editing genes that will allow them to work with the DNA of an ordinary pigeon.
So far they have taken several approaches to improve the efficiency of the tool. The best way is direct editing of the sperm or the egg of a dove, because these changes will be transmitted to the next generation. What’s the problem? Scientists are still not able to grow these cells in vitro.
The following important point: the introduction of a tool to edit DNA with the necessary tools in the embryo. But scientists and here faced a problem: they had to rely on viruses for delivery of CRISPR tools. As a result, the pack became too big for that, so it can be safe to implement.
To circumvent these obstacles, the team Novak has focused its efforts on the creation of a completely new line of pigeons, each of which contains the genetic material for easier editing of DNA.
CRISPR-Cas9 is a two-step process, explains Novak. Part CRISPR lies in the target DNA, whereas the Cas9 carries out the cutting. Birds bred with Cas9 in every cell, there is a part functional tool for editing genes in their bodies, which greatly facilitates the delivery of other essential nutrients.
“In the next three years the world may see the first genetic traits of the passenger pigeon, reborn into the living, breathing birds,” says Novak.
If all goes as planned, in the next twenty years we will witness the revival of extinct species. Dodo birds, and woolly mammoths, too, will be resurrected. Sooner or later, the extinction will remain a thing of the past — the worst and best to do.
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