Exterminating invasive species with gene drives

I can’t rave enough about Jennifer Kahn’s recent TED talk entitled Gene Editing Can Now Change an Entire Species.  The talk summarizes the new power of gene drives to eradicate malaria, dengue and yellow fever, and other dangerous diseases spread by insects.  It is truly a brave new world.    CRISPR (Clustered regularly interspaced short palindromic repeats) is a gene editing tool which allows scientists to edit genes precisely.  In Kahn’s phrasing, it is a “word processor for genes”.   Gene drives not only use CRISPR technology to edit genes but also include the mechanics of CRISPR in the DNA to enable the new gene to be passed on to offspring.

Among the intriguing uses of the new technology is to potentially rid the planet of invasive species that threaten indigenous ones.  A good example is the Asian carp that has invaded our Great Lakes.  Incorporate a gene drive in the Asian carp that has it producing only male offspring and within a matter of generations, the Asian carp will be gone.  Of course, Kahn gives the necessary genuflections toward the need to come to agreement on the ethical issues involved, but the future applications are breathtaking.

I remember reading the superb book Rat Island by William Stolzenburg1 about the monumental attempts that have taken place, primarily since the 1970s, to eliminate invasive species, particularly on islands.  Indigenous species are no match for invasive predators such as rats, feral cats, and a host of other animals that have hitched a ride with humans to these islands.  You can imagine why species like the flightless kakapoo, have been decimated or pushed to extinction at the hands of predators these species have been evolutionarily unprepared for.



Kahn makes a great point.  Using gene drives to eradicate species may backfire.  What if modified Asian carps return to Asia (let’s not forget, they are invasive species)?  The gene drive could wipe out the entire Asian carp population worldwide.  But the good news is that there is a reversal gene drive which can change the modified carp back to normal should they reach their home territories.  I know the new technology will have to go through a myriad of ethical panels and boards but ultimately it may have come just in time to save many species from the finality of extinction via invasive species.

The primary method of killing invasive rats has been through bait laced with Brodifacoum.  The poison is an anticoagulant and eventually causes the rat’s blood vessels to “leak” and, after about a week, the animal bleeds out.  Studies have shown it is probably a quite painful way to die.  As one might imagine, this has caused angst among conservationist.  On the one hand they want to return habitats to their pristine beauty, but on the other hand, the death of creatures, even rats, has caused somewhat of a “Sophie’s choice”.   The majority of conservationists have come down on the side of eradication in the face of massive island species extinctions.  David Steadman of the University of Florida estimated2 that 8,000 populations have disappeared from the islands of Oceania (about 800 islands).  Turns out there was an unintended outcome of using these poisons (isn’t there always?).  Some birds of prey including the bald eagle were eating the poisoned rats and dying.

Gene drives may be the silver bullet in the eradication of invasive species.  Conservationists using the new technology can avoid the need to kill targeted animals.  And no bykill!  I know, I know, we need to test the process to make sure we avoid all the potential unintended consequences, but even if it is only partially successful, it could be huge for the environment.

I vividly remember reading E. O. Wilson’s The Diversity of Life3 as he detailed the enchanting story of the repopulation of what was left of Krakatoa volcano after it blew itself out of the water in 1883.  It is clear that there is a capriciousness to repopulation.  Many species find themselves carried or blown to remote islands by currents, storms, and even tsunamis.   And in time, they may evolve into new species adapting to the often hostile new environments.  But why are these early inhabitants given precedence over late arrivals?  It appears to rest on the assumption that humans are unnatural – not part of the natural environment.  And therefore, if other animals tag along with us as a human food source for long voyages, or as our pets, or even surreptitiously, they are somehow unnatural in the grander scheme of things, demanding eradication.  You cannot read Rat Island and not be repulsed by the way rats prey on other creatures.   I am certainly not against the eradication of these invasive species, but it is not an easy thing deciding what lives and dies.

  1. Stolzenburg, W. (2011) Rat Island: Predators in Paradise and the World’s Greatest Wildlife Rescue: New York, Bloomsbury
  2. Steadman, D. W. (1995) Prehistoric extinctions of Pacific Island brids: Biodiversity meets zooarchaeology: Science, 267, p. 1123- 1131.
  3. Wilson, E. O., (1999) The Diversity of Life: W. W. Norton & Company
15 replies
  1. lindsirusso1
    lindsirusso1 says:

    This blog explains the use of technology attempting to eliminate dangerous and threatening species. Such include insets that carry deadly diseases from one organism to the next and Asian carp that invade the Great Lakes. One way to potentially eliminate these species is to edit those species’ genes through CRISPR technology. This editing tool ensures that a certain trait is passed down from parent to its offspring. It eventually leads to genetic changes throughout the entire species. While some say gene drives show many promising benefits for the future and could be very useful, in return some fear the impacts of permanently altering life forms and possibly becoming irreversible. Due to previous methods of killing off invasive species in a suffering, nonhuman way, this new technology will have to go through many boards and ethical panels. The process needs to be tested to make sure there are no unforeseen results or consequences that can potentially harm the environment, but if proven to work it could be seen as a positive impact.

  2. NikDallas
    NikDallas says:

    The idea of exterminating invasive species with gene drives is an absolutely mind blowing concept. It is incredible to realize that science and technology has improved so much that there is a gene editing tool called CRISPR (Clustered regularly inter spaces short palindromic repeats) that can actually allow scientists to edit genes precisely. This idea is conceptually an amazing solution to eradicating invasive species, especially those that are the cause of decreasing diversity and extinction of native creatures. Though ethical and possibly moral issues arising about the context and boundaries within this can be sued and the fairness of humans to be able to hold such power as to ‘decide what lives’, in the long run it seems to be a feasible solution to exterminating invasive species. The idea of killing rats (even though they seem to be gross creatures) may be a conceptually harsh idea, but if it could protect many other species from extinction then is it not a small enough price to pay? Also, the article does explain that gene drives to exterminate invasive species isn’t aimed at making these invasive species extinct, but simply at trying to kill out these invasive species where they do not belong to give the native creatures there a chance to live and diversify naturally. They are trying to leave these species where they originated, not make them completely extinct.

  3. madisonclark
    madisonclark says:

    This article goes to describe a relatively new technology known as CRISPR, a gene editing tool that has the potential ability to get rid of invasive species that may be at harm to indigenous species. The tool may not only edit genes, but it can also enable new genes to be passed on to offspring. Arguments have been made on whether this technology would be the best route to take on the issue; Some say that this technique has the power to save species that are in danger of extinction. Though there may be some cons to the situation, overall the technology could avoid the need to kill targeted species. This could very well be a positive change for the environment.

  4. lindsirusso1
    lindsirusso1 says:

    After reading this post, I couldn’t help but do more research and read further on this discussion. I found a related article that I agreed strongly with. Basically stating that because we as humans are affected by the state of our ecosystems, public oversight of research, data, and findings is crucial and us as a society should be well-informed. They also stated that they society should be able to decide how to manage our environment. I found that very refreshing that these researchers value the opinions of the whole society.

    It’s amazing the technology we have today that allows us to modify gene make up in certain spices and organisms, giving us the ability to eliminate and/or temporarily remove them from the ecosystem. I cant help but think or imagine that the invasive species over time would have the ability to adapt and evolve to the gene drive, in return becoming immune or resistant to the modifications.
    As long as there is no suffering or inhumane practice being conducted on these species I would strongly support this movement and would encourage others to be involved or at least well educated on this topic.

  5. cbozek
    cbozek says:

    Very interesting post. I like seeing alternative methods of removing invasive species that threaten native ones. As you discussed in the article I feel like using gene drives to eliminate the unwanted species in certain areas where they are not native helps sway the conservationists that argue the obvious ethical concerns when it comes to eliminating a species. A good point is brought up with the Asian carp example. What would happen if the modified species did make its way back to its native habitats and started depopulating the remaining native species. The question I suppose would need to be answered as to what the main reason is that the invasive species ended up in the non native lands in the first place. I feel if the majority of the responsibility of this is due to humans the risk of the modified gened species returning to the native population would be low. There would need to be testing protocols implemented on on the native species habits to monitor whether this is becoming a concern or not. Methods like this must be explored as alternatives because as Steadman detailed eradication with poisons did have negative impacts on the native species. It would be hard to contain the population of the invasive species to avoid native natural predators from preying on the infected invasive species. Deciding what species lives and dies will always be a difficult conversation and decision but you have to look at the decision on a large scale. Would letting the invasive species continue to reproduce and compete with native species result in eliminating the natives? If they were eliminated what effects would that have on the ecosystem as a whole? I feel that most importantly though you have to ask what affects will it have on humans, as hard a question to answer and closed minded as that may sound, if it came down to animals or humans I would be surprised if anyone did not choose the latter. It would be a long process to confirm that the unintended and indirect consequences are minimal but a method that eliminates the invasive species with no by-kill is a huge advantage.

  6. cbozek
    cbozek says:

    I really enjoyed reading this article. I feel like there needs to be more publication about these type of methods to eliminate invasive animal species. I have never heard of gene drives as a method for dealing with this growing situation. There are many instances right here in Florida that this type of strategy could be implemented to help decrease the number of invasive species that are negatively affecting native ones specifically in our marine life. Over the last 25 years the population of lion fish has increased immensely in Florida, first showing up on the Atlantic coast in 1985 and as recent as the last 5 years they have begun populating on the gulf coast. This species poses a large threat to the native species of fish that inhabit the same areas as the invasive lion fish. The predatory lion fish feeds on smaller native fish and this has negative effects to overall reef habitat and health as they are eliminating species that have important ecological roles such as ones that control the algae amounts on the reef, in addition, the lion fish competes for food with native predatory fish such as snapper and grouper. In 2013 the FWC (Fish and Wildlife Commission) increased the harvesting opportunities of lion fish eliminating recreational and commercial bag limits. As an avid Florida fisherman I can definitely appreciate alternative methods of eliminating invasive species that threaten our native species that I often target. As you mentioned there are several ethical implications to consider but a method that prevents the species from reproducing as opposed to just eradicating the species all together seems to be something that will satisfy all parties involved and most importantly, the native species.

  7. courtney piccirilo
    courtney piccirilo says:

    this article was a little disturbing seeing that scientists are able to manipulate genes with animals, makes me wonder and worry with the technology and knowledge increasing as time goes on eventually they are going to start using it on humans. If it is not used on humans some way we are still going to be affected due to animals eating others that were infected such as the rats it will eventually pass on to a animal that humans eat and then they will get sick and die.

  8. Trista Broome
    Trista Broome says:

    I enjoyed this article, and thought the multiple examples you provided of different failed methods of the removal of invasive species was very helpful. I was curious though, after reading the introduction, to hear more about how CRISPR technology actually works. How, in fact, does it have the capability of rewriting genes? I support the idea of making the offspring infertile to prevent the future of invasive species. However, I do not support the current methods of poaching invasive species, as it is not the animals’ fault that they are there, it is ours. I do not find this method humane. This is what will make CRISPR technology so important for the future of life on earth. It will help us correct our wrongs, and to create a more successful future for the native species of different regions, and to help eliminate the extinction rates that are so drastically high right now.

  9. Elizabeth Rubiano
    Elizabeth Rubiano says:

    After rereading, I noticed that you said there was a reversal gene that could be used to change the modified animal back to their original state upon reaching their original environments, which answers the question of the how the targeted animals will not be killed. This ultimately changes my whole mindset on gene drives. If this device has the ability to save animals from the treat of invasive species while saving the invasive species and returning them back to their former state than we should definitely make use of this tool. Though it will have to go through many ethical panels and boards, like you said, it offers benefits to both sides, even conservationist who might be on the fence about the idea. Of course the gene drives will not be able to fully stop invasive species from entering unwarranted places due to the changing environment and many will die before they are even able to return home, but even if there is some positive outcome by it, why shouldn’t we try? I still agree that we should let the earth and it’s inhabitants be, but for the sake of saving animals close to extinction, gene drives will play a vital role.

    • Marc Defant
      Marc Defant says:

      I just wanted to make sure you understand that the invasive species are not “killed”. They will just have offspring that will not be able to reproduce. Therefore the invasive species that are already in the region will live out their lives but their offspring will be kept from reproducing. As I pointed out in the article, this is much more humane than the poisoning and other things that are taking place now.

  10. Elizabeth Rubiano
    Elizabeth Rubiano says:

    I thought this article was very insightful and shed some interesting light on gene drives. The concept of gene drives is truly amazing and evolutionary, but is very controversial and complex at the same time. The idea of eliminating invasive species is entirely mesmerizing, but not when it still brings potential harm to the very animals it is supposed to be saving. Also, you said that gene drives can be used in a way where targeted animals will not get killed, but how will this happen? What plan of action will be taken in order to make this happen? Once that issue is resolved, I think gene drives will be very useful, but for now it should not be used if it going to harm either the targeted animals or the non-targeted animals. Also, why should some of these invasive animals be punished or killed when many have been displaced? Eventually animals and plants are going to evolve in new places so why should me medal in that just because we discovered some new technology. Sometimes we should let the earth and its inhabitants be and let them evolve in the natural processes that occur.

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