‘Gene drives’ could wipe out whole populations of pests in one fell swoop



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Gene drives aim to deliberately spread bad genes when invasive species such as mice reproduce.
Colin Robert Varndell/shutterstock.com

Thomas Prowse, University of Adelaide; Joshua Ross, University of Adelaide; Paul Thomas, University of Adelaide, and Phill Cassey, University of Adelaide

What if there was a humane, targeted way to wipe out alien pest species such as mice, rats and rabbits, by turning their own genes on themselves so they can no longer reproduce and their population collapses?

Gene drives – a technique that involves deliberately spreading a faulty gene throughout a population – promises to do exactly that.

Conservationists are understandably excited about the possibility of using gene drives to clear islands of invasive species and allow native species to flourish.


Read more: Gene drives may cause a revolution, but safeguards and public engagement are needed.


Hype surrounding the technique continues to build, despite serious biosecurity, regulatory and ethical questions surrounding this emerging technology.

Our study, published today in the journal Proceedings of the Royal Society B, suggests that under certain circumstances, genome editing could work.

The penguins on Antipodes Island currently live alongside a 200,000-strong invasive mouse population.
Wikimedia Commons, CC BY

Good and bad genes

The simplest way to construct a gene drive aimed at suppressing a pest population is to identify a gene that is essential for the pest species’ reproduction or embryonic development. A new DNA sequence – the gene-drive “cassette” – is then inserted into that gene to disrupt its function, creating a faulty version (or “allele”) of that gene.

Typically, faulty alleles would not spread through populations, because the evolutionary fitness of individuals carrying them is reduced, meaning they will be less likely than non-faulty alleles to be passed on to the next generation. But the newly developed CRISPR gene-editing technology can cheat natural selection by creating gene-drive sequences that are much more likely to be passed on to the next generation.


Read more: Now we can edit life itself, we need to ask how we should use such technology.


Here’s how the trick works. The gene-drive cassette contains the genetic information to make two new products: an enzyme that cuts DNA, and a molecule called a guide RNA. These products act together as a tiny pair of molecular scissors that cuts the second (normal) copy of the target gene.

To fix the cut, the cell uses the gene drive sequence as a repair template. This results in a copy of the gene drive (and therefore the faulty gene) on both chromosomes.

This process is called “homing” and, when switched on in the egg- or sperm-producing cells of an animal, it should guarantee that almost all of their offspring inherit the gene-drive sequence.

As the gene-drive sequence spreads, mating between carriers becomes more likely, producing offspring that possess two faulty alleles and are therefore sterile or fail to develop past the embryonic stage.

Will it work?

Initial attempts to develop suppression drives will likely focus on invasive species with rapid life cycles that allow gene drives to spread rapidly. House mice are an obvious candidate because they have lots of offspring, they have been studied in great detail by biologists, and have colonised vast areas of the world, including islands.

In our study we developed a mathematical model to predict whether gene drives can realistically be used to eradicate invasive mice from islands.

Our results show that this strategy can work. We predict that a single introduction of just 100 mice carrying a gene drive could eradicate a population of 50,000 mice within four to five years.

But it will only work if the process of genetic homing – which acts to overcome natural selection – functions as planned.

Evolution fights back

Just as European rabbits in Australia have developed resistance to the viruses introduced to control them, evolution could thwart attempts to use gene drives for biocontrol.

Experiments with non-vertebrate species show that homing can fail in some circumstances. For example, the DNA break can be repaired by an alternative mechanism that stitches the broken DNA sequence back together without copying the gene-drive template. This also destroys the DNA sequence targeted by the guide RNA, producing a “resistance allele” that can never receive the gene drive.

A recent study in mosquitos estimated that resistance alleles were formed in at least 2% of homing attempts. Our simulation experiments for mice confirm this presents a serious problem.

After accounting for low failure rates during homing, the creation and spread of resistance alleles allowed the modelled populations to rebound after an initial decline in abundance. Imperfect homing therefore threatens the ability of gene drives to eradicate or even suppress pest populations.

One potential solution to this problem is to encode multiple guide RNAs within the gene-drive cassette, each targeting a different DNA sequence. This should reduce homing failure rates by allowing “multiple shots on goal”, and avoiding the creation of resistance alleles in more cases.

To wipe out a population of 200,000 mice living on an island, we calculate that the gene-drive sequences would need to contain at least three different guide RNA sequences, to avoid the mice ultimately getting the better of our attempts to eradicate them.

From hype to reality

Are gene drives a hyperdrive to pest control, or just hype? Part of the answer will come from experiments with gene drives on laboratory mice (with appropriate containment). That will help to provide crucial data to inform the debate about their possible deployment.

The ConversationWe also need more sophisticated computer modelling to predict the impacts on non-target populations if introduced gene drives were to spread beyond the populations targeted for management. Using simulation, it will be possible to test the performance and safety of different gene-drive strategies, including strategies that involve multiple drives operating on multiple genes.

Thomas Prowse, Postdoctoral research fellow, School of Mathematical Sciences, University of Adelaide; Joshua Ross, Associate Professor in Applied Mathematics, University of Adelaide; Paul Thomas, , University of Adelaide, and Phill Cassey, Assoc Prof in Invasion Biogeography and Biosecurity, University of Adelaide

This article was originally published on The Conversation. Read the original article.

Who’s afraid of the giant African land snail? Perhaps we shouldn’t be



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Giant African land snails can grow up to 15cm long.
Author provided

Luke S. O’Loughlin, La Trobe University and Peter Green, La Trobe University

The giant African land snail is a poster child of a global epidemic: the threat of invasive species. The snails are native to coastal East Africa, but are now found across Asia, the Pacific and the Americas – in fact, almost all tropical mainlands and islands except mainland Australia.

Yet, despite their fearsome reputation, our research on Christmas Island’s invasive snail population suggests the risk they pose to native ecosystems has been greatly exaggerated.

Giant African land snails certainly have the classic characteristics of a successful invader: they can thrive in lots of different places; survive on a broad diet; reach reproductive age quickly; and produce more than 1,000 eggs in a lifetime. Add it all together and you have a species recognised as among the worst invaders in the world.

The snails can eat hundreds of plant species, including vegetable crops (and even calcium-rich plaster and stucco), and have been described as a major threat to agriculture.

They have been intercepted at Australian ports, and the Department of Primary Industries concurs that the snails are a “serious threat”.

Despite all this, there have been no dedicated studies of their environmental impact. Some researchers suggest the risk to agriculture has been exaggerated from accounts of damage in gardens. There are no accounts of giant African land snails destroying natural ecosystems.

Quietly eating leaf litter

In research recently published in the journal Austral Ecology, we tested these assumptions by investigating giant African land snails living in native rainforest on Christmas Island.

Giant African land snails have spread through Christmas Island with the help of another invasive species: the yellow crazy ant.

Until these ants showed up, abundant native red land crabs ate the giant snails before they could gain a foothold in the rainforest. Unfortunately, yellow crazy ants have completely exterminated the crabs in some parts of the island, allowing the snails to flourish.

We predicted that the snails, which eat a broad range of food, would have a significant impact on leaf litter and seedling survival.

Unexpectedly, the snails we observed on Christmas Island confined themselves to eating small amounts of leaf litter.
Author provided

However, our evidence didn’t support this at all. Using several different approaches – including a field experiment, lab experiment and observational study – we found giant African land snails were pretty much just eating a few dead leaves and little else.

We almost couldn’t distinguish between leaf litter removal by the snails compared to natural decomposition. They were eating leaf litter, but not a lot of it.

We saw almost no impact on seedling survival, and the snails were almost never seen eating live foliage. In one lab trial, we attempted to feed snails an exclusive diet of fresh leaves, but so many of these snails died that we had to cut the experiment short. Perhaps common Christmas Island plants just aren’t palatable.

It’s possible that the giant African land snails are causing other problems on Christmas Island. In Florida, for example, they carry parasites that are a risk to human health. But for the key ecological processes we investigated, the snails do not create the kind of disturbance we would assume from their large numbers.

We effectively excluded snails from an area by lining a fence with copper tape.
Author provided

The assumption that giant African land snails are dangerous to native plants and agriculture comes from an overriding sentiment that invasive species are damaging and must be controlled.

Do we have good data on the ecological impact of all invasive species? Of course not. Should we still try to control all abundant invasive species even if we don’t have evidence they are causing harm? That’s a more difficult question.

The precautionary principle drives much of the thinking behind the management of invasive species, including the giant African land snail. The cost of doing nothing is potentially very high, so it’s safest to assume invasive species are having an effect (especially when they exist in high numbers).

But we should also be working hard to test these assumptions. Proper monitoring and experiments give us a true picture of the risks of action (or inaction).

The ConversationIn reality, the giant African land snail is more the poster child of our own knee-jerk reaction to abundant invaders.

Luke S. O’Loughlin, Research fellow, La Trobe University and Peter Green, Head of Department, Ecology, Environment and Evolution, La Trobe University

This article was originally published on The Conversation. Read the original article.

Publish and don’t perish – how to keep rare species’ data away from poachers



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Birdwatchers are keeping the location of the newly rediscovered night parrot a closely guarded secret.
Adventure Australia, Author provided

Andrew Lowe, University of Adelaide; Anita Smyth, University of Adelaide; Ben Sparrow, University of Adelaide, and Glenda Wardle, University of Sydney

Highly collectable species, especially those that are rare and threatened, can potentially be put at risk from poaching if information describing where they can be found is published. But rather than withholding this information, as has been recently recommended, scientists should publish such information through secure data repositories so that this knowledge can continue to be used to help conserve and manage the world’s most threatened species.

Scientists are encouraged to publish data so their discoveries can be shared and scrutinised. However, a recent article has identified the risks of publishing the locations of rare, endangered or newly described species.

The example of the Chinese cave gecko shows that these concerns may be warranted. The species went extinct at the location where it was discovered, potentially at the hands of scientifically literate poachers.

But instead of withholding such information, we suggest (in a letter published today in Science) that scientists can publish sensitive data securely, while minimising the risk of misuse, by using one of a range of currently available tools.

A little knowledge

Typically, the problem for threatened species is not that too much information is available on their population and location, but rather quite the opposite. For example, in New South Wales more than 150 species have missed out on conservation funding because of a lack of such information.

On the flip side, there is little evidence that encouraging researchers to withhold this information will thwart people who are determined to find specific species. Collectors who specialise in highly collectable species can get location information from a variety of sources such as wildlife trade websites, pet and naturalist clubs, social media, and the popular press. This is despite the range of laws, regulations (such as scientific and collecting permits) and community reporting aimed at restricting the collection and trade of endangered species.

Grove of Wollemi pine, the location of which has been kept secret for more than 25 years.
Jaimie Plaza

How to publish sensitive data

Many governments have implemented sensitive data policies to protect ecological and species data, based on their own lists of sensitive species. Many of these policies have been in place for almost a decade and have kept secure the locations of hundreds of highly collectable species such as Australia’s Wollemi pine.

These policies are practised by numerous data portals worldwide, including DataONE, South Africa’s National Biodiversity Institute, Australia’s Virtual Herbarium, Australia’s Department of Environment, the Global Biodiversity Information Facility, the Terrestrial Ecosystem Research Network, and the Atlas for Living Australia.

A wealth of advice is also available to researchers and data managers on how to manage sensitive species information, such as the guidance provided by Science International and the Australian National Data Service. Science journals also work closely with open data repositories to ensure that sensitive species information is securely published – see, for example, the policies of leading journals Science and Nature.

Information entropy – why it’s a good idea to publish data before they are lost in the mists of time.
Michener (2006) Ecol. Informatics

One example of good data management is the AEKOS data portal run by Australia’s Terrestrial Ecosystem Research Network (TERN). AEKOS contains data from different government monitoring surveys covering almost 100,000 sites across the country. Its default position is to make ecological data and information freely available for land-management or wildlife research.

However, sensitive data are flagged during the early stages of the publishing process. The data are then secured in one of three ways:

  • masking sensitive information by giving only approximate locations or non-specific species names

  • making data available only after approval by the legal owners

  • embargoing the data for a maximum of two years.

To ensure data trustworthiness, TERN’s data reviewers further check for any data sensitivities that may have been overlooked during submission.

What’s the alternative?

We recognise the importance of keeping the locations of highly collectable species secure, and the need for caution in publishing precise site locations. But despite recent concerns, the examples given above show how online scientific data publishing practices have sufficiently matured to minimise misuses such as illegal or excessive collection, disturbance risk, and landholder privacy issues.

The alternative is not to deposit these valuable data at all. But this risks the loss of vital knowledge in the quest to protect wildlife.

In tackling poaching, we should perhaps seek to motivate poachers to help protect our most endangered wildlife. Such tactics are thought by some to have contributed to the discovery of several endangered bird species populations, and potentially the recent rediscovery of the night parrot, after a century of elusiveness in Australia. If poachers are willing to turn gamekeeper, getting them to share their rare species knowledge securely would certainly improve conservation outcomes.


The ConversationThe authors acknowledge their co-signatories of the letter published in Science: Ken Atkins (WA Department of Parks and Wildlife), Ron Avery (NSW Office of Environment and Heritage), Lee Belbin (Atlas of Living Australia), Noleen Brown (Qld Department of Science, Information Technology and Innovation), Amber E. Budden (DataONE, University of New Mexico), Paul Gioia (WA Department of Parks and Wildlife), Siddeswara Guru (TERN, University of Queensland), Mel Hardie (Victoria Department of Environment, Land, Water and Planning), Tim Hirsch (Global Biodiversity Information Facility), Donald Hobern (Global Biodiversity Information Facility), John La Salle (Atlas of Living Australia, CSIRO), Scott R. Loarie (California Academy of Sciences), Matt Miles (SA Department of Environment, Water and Natural Resources), Damian Milne (NT Department of Environment and Natural Resources), Miles Nicholls (Atlas of Living Australia, CSIRO), Maurizio Rossetto (National Herbarium of NSW), Jennifer Smits (ACT Environment, Planning and Sustainable Development Directorate), Gregston Terrill (ACT Department of Environment and Energy), and David Turner (University of Adelaide).

Andrew Lowe, Director of Food Innovation, University of Adelaide; Anita Smyth, Data manager, TERN, University of Adelaide; Ben Sparrow, Associate professor and Director – TERN AusPlots and Eco-informatics, University of Adelaide, and Glenda Wardle, Professor in Ecology and Evolution, University of Sydney

This article was originally published on The Conversation. Read the original article.

Zoos aren’t Victorian-era throwbacks: they’re important in saving species



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A meerkat at the National Zoo and Aquarium in Canberra. The Zoo has recently announced an expansion that will double its size.
AAP Image/Stefan Postles

Alienor Chauvenet, The University of Queensland

The National Zoo and Aquarium in Canberra recently announced a new expansion that will double its size, with open range space for large animals like white rhinos and cheetahs.

As well as improving visitors’ experience, the expansion is touted as a way to improve the zoo’s breeding program for threatened animals. However, zoos have received plenty of criticism over their capacity to educate, conserve, or even keep animals alive.

But while zoos began as 19th-century menageries, they’ve come a long way since then. They’re responsible for saving 10 iconic species worldwide. Without captive breeding and reintroduction efforts, there might be no Californian Condor or Przewalski’s Horse – the only truly wild horse – left in the wild.

Australian zoos form part of a vital global network that keeps our most vulnerable species alive.

What is the role of zoos for conservation?

Although Canberra Zoo is relatively new compared with others in Australia – Melbourne zoo, for example, was opened in 1862 – it adds to a collection of conservation-orientated establishments.

In Australia, Taronga Conservation Society Australia, the Royal Melbourne Zoological Gardens, Adelaide Zoo and Perth Zoo are all members of the World Association of Zoos and Aquariums (WAZA). WAZA is an international organisation that aims to guide and support zoos in their conservation missions, including captive breeding, reintroductions into the wild, habitat restoration, and genetic management.

From the perspective of nature conservation, zoos have two major roles: educating the public about the plight of our fauna, and contributing to species recovery in the wild.

Conservation education is deeply embedded in the values of many zoos, especially in Australia. The evidence for the link between zoo education and conservation outcomes is mixed, however zoos are, above anybody else, aimed at children. Evidence shows that after guided experiences in zoos children know more about nature and are more likely to have a positive attitude towards it. Importantly, this attitude is transferable to their parents.

Zoos contribute unique knowledge and research to support field conservation programs, and thus species recovery. In Australia, zoos are directly involved in monitoring of free-ranging native fauna and investigations into emerging diseases. Without zoos many fundamental questions about a species’ biology could not be answered, and we would lack essential knowledge on animal handling, husbandry and care.

Through captive breeding, zoos can secure healthy animals that can be introduced to old or new habitats, or bolster existing wild populations. For example, a conservation manager at Taronga Zoo told me they’ve released more than 50,000 animals that were either bred on-site or rehabilitated in their wildlife hospitals (another important function of zoos).

Criticisms of captive breeding programs

The critics of captive breeding as a conservation strategy raise several concerns. Captive bred population can lose essential behavioural and cultural adaptations, as well as genetic diversity. Large predators – cats, bears and wolves – are more likely to be affected.

Some species, such as frogs, do well in captivity, breed fast, and are able to be released into nature with limited or no training. For others, there is usually a concerted effort to maintain wild behaviour.

There’s a higher chance of disease wiping out zoo populations due to animal proximity. In 2004 the largest tiger zoo in Thailand experienced an outbreak of H5N1 bird flu after 16 tigers were fed contaminated raw chicken; ultimately 147 tigers died or were put down.

However, despite these risks, research shows that reintroduction campaigns improve the prospects of endangered species, and zoos can play a crucial role in conservation. Zoos are continually improving their management of the genetics, behaviour and epidemiology of captive populations.

They are the last resort for species on the brink of extinction, such as the Orange-bellied Parrot or the Scimitar-horned Oryx, and for those facing a threat that we cannot stop yet, such as amphibians threatened by the deadly Chytrid fungus.

Orange-bellied parrots are ranked among the most endangered species on the planet – their survival depends on zoos.
Chris Tzaros/AAP

Zoos need clear priorities

A cost-benefit approach can help zoos prioritise their actions. Taronga, for example, uses a prioritisation system to decide which projects to take on, with and without captive breeding. Their aim is to a foresee threats to wildlife and ecosystems and implement strategies that ensure sustainability.

Developing prioritisation systems relies on clearly defined objectives. Is there value in keeping a species in captivity indefinitely, perhaps focusing only on education? Is contributing to a wild population the end goal, requiring both education and active conservation?

Once this is defined, zoos can assess the benefit and costs of different actions, by asking sometimes difficult questions. Is a particular species declining in the wild? Can we secure a genetically diverse sample before it is too late? Will capturing animals impact the viability of the wild population? How likely is successful reintroduction? Can we provide enough space and stimulation for the animals, and how expensive are they to keep?

Decision science can help zoos navigate these many factors to identify the best species to target for active captive conservation. In Australia, some of the rapidly declining northern mammals, which currently do not have viable zoo populations, could be a good place to start.

Partnerships with governmental agencies, universities and other groups are essential to all of these activities. Zoos in Australia are experts at engaging with these groups to help answer and address wildlife issues.


The ConversationAlienor Chauvenet would like to acknowledge the contribution of Hugh Possingham to this article, and thank Nick Boyle and Justine O’Brien from Taronga Conservation Society Australia for the information they provided.

Alienor Chauvenet, Postdoctoral Research Fellow, The University of Queensland

This article was originally published on The Conversation. Read the original article.

Scientists are accidentally helping poachers drive rare species to extinction



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The beautiful Chinese cave gecko, or Goniurosaurus luii, is highly prized by poachers.
Carola Jucknies

Benjamin Scheele, Australian National University and David Lindenmayer, Australian National University

If you open Google and start typing “Chinese cave gecko”, the text will auto-populate to “Chinese cave gecko for sale” – just US$150, with delivery. This extremely rare species is just one of an increasingly large number of animals being pushed to extinction in the wild by animal trafficking.

What’s shocking is that the illegal trade in Chinese cave geckoes began so soon after they were first scientifically described in the early 2000s.

It’s not an isolated case; poachers are trawling scientific papers for information on the location and habits of new, rare species.

As we argue in an essay published today in Science, scientists may have to rethink how much information we publicly publish. Ironically, the principles of open access and transparency have led to the creation of detailed online databases that pose a very real threat to endangered species.

We have personally experienced this, in our research on the endangered pink-tailed worm-lizard, a startling creature that resembles a snake. Biologists working in New South Wales are required to provide location data on all species they discover during scientific surveys to an online wildlife atlas.

But after we published our data, the landowners with whom we worked began to find trespassers on their properties. The interlopers had scoured online wildlife atlases. As well as putting animals at risk, this undermines vital long-term relationships between researchers and landowners.

The endangered pink-tailed worm-lizard (Aprasia parapulchella).
Author provided

The illegal trade in wildlife has exploded online. Several recently described species have been devastated by poaching almost immediately after appearing in the scientific literature. Particularly at risk are animals with small geographic ranges and specialised habitats, which can be most easily pinpointed.

Poaching isn’t the only problem that is exacerbated by unrestricted access to information on rare and endangered species. Overzealous wildlife enthusiasts are increasingly scanning scientific papers, government and NGO reports, and wildlife atlases to track down unusual species to photograph or handle.

This can seriously disturb the animals, destroy specialised microhabitats, and spread disease. A striking example is the recent outbreak in Europe of a amphibian chytrid fungus, which essentially “eats” the skin of salamanders.

This pathogen was introduced from Asia through wildlife trade, and has already driven some fire salamander populations to extinction.

Fire salamanders have been devastated by diseases introduced through the wildlife trade.
Erwin Gruber

Rethinking unrestricted access

In an era when poachers can arm themselves with the latest scientific data, we must urgently rethink whether it is appropriate to put detailed location and habitat information into the public domain.

We argue that before publishing, scientists must ask themselves: will this information aid or harm conservation efforts? Is this species particularly vulnerable to disruption? Is it slow-growing and long-lived? Is it likely to be poached?

Fortunately, this calculus will only be relevant in a few cases. Researchers might feel an intellectual passion for the least lovable subjects, but when it comes to poaching, it is generally only charismatic and attractive animals that have broad commercial appeal.

But in high-risk cases, where economically valuable species lack adequate protection, scientists need to consider censoring themselves to avoid unintentionally contributing to species declines.

Restricting information on rare and endangered species has trade-offs, and might inhibit some conservation efforts. Yet, much useful information can still be openly published without including specific details that could help the nefarious (or misguided) to find a vulnerable species.

There are signs people are beginning to recognise this problem and adapt to it. For example, new species descriptions are now being published without location data or habitat descriptions.

Biologists can take a lesson from other fields such as palaeontology, where important fossil sites are often kept secret to avoid illegal collection. Similar practices are also common in archaeology.

Restricting the open publication of scientifically and socially important information brings its own challenges, and we don’t have all the answers. For example, the dilemma of organising secure databases to collate data on a global scale remains unresolved.

For the most part, the move towards making research freely available is positive; encouraging collaboration and driving new discoveries. But legal or academic requirements to publish location data may be dangerously out of step with real-life risks.

The ConversationBiologists have a centuries-old tradition of publishing information on rare and endangered species. For much of this history it was an innocuous practice, but as the world changes, scientists must rethink old norms.

Benjamin Scheele, Postdoctoral Research Fellow in Ecology, Australian National University and David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University

This article was originally published on The Conversation. Read the original article.

Widespread invasive species control is a risky business



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Partula snails were driven to extinction in the wild by introduced predators.
Wikimedia Commons

R. Keller Kopf, Charles Sturt University; Dale Nimmo, Charles Sturt University, and Paul Humphries, Charles Sturt University

In 1977, on the islands of French Polynesia, government authorities released a predatory snail. They hoped this introduction would effectively control another species of invasive snail, previously introduced to supply escargot.

Instead, by the early 1980s, scientists reported alarming declines of native snail populations. Within ten years, 48 native snail species (genus Partula) had been driven to extinction in the wild.

The extinction of the Partula is notorious partially because these snails were, before going extinct, the study subjects of the first test in nature of Darwin’s theory of evolution by natural selection.

In the decades since, attempts to control and eradicate invasive species have become common, generally with far better results.

However, our paper, published today in Nature Ecology and Evolution, highlights the importance of scientific evidence and independent assessments when deciding whether to control or eradicate invasive species.

From islands to continents

Increasingly, large-scale invasive species control initiatives are being proposed worldwide. As early as 2018, a herpes virus will be released in Australia’s largest river system, targeting invasive common carp. As part of its Threatened Species Strategy, Australia is also planning to kill two million feral cats.

Across the Tasman Sea, New Zealand has made a bold commitment to remove three groups of invasive predators entirely by 2050.

New Zealand looks to eradicate three groups of invasive predators: rodents, mustelids, and the common brushtail possum.
Geoff Whalan/Flickr, CC BY-NC-SA

It’s not just Australians and Kiwis making ambitious invasive species control proposals: bounties are being paid to catch invasive fish in the United States. The European Union has blacklisted 37 species of plants and animals within 4 million square kilometres, many of which are well-established and will be targeted by control (not preventative) measures.

Meanwhile, new gene editing technology has made the continental-scale eradication of invasive species a real possibility, for example by implementing gene drives that reduce breeding success. If you haven’t heard of it, CRISPR is a startling new biotechnology that makes genetic modification of plants and animals much easier. It offers new potential solutions to some of the world’s worst environmental, agricultural and human health problems.

These schemes will be implemented across large and complex social-ecological systems, and some options – like releasing a virus or genetically engineered species – may be irreversible.

Managing risk

While these projects may yield great benefits, we must be aware of the potential risk of unexpected and undesirable outcomes.

A prime example is the project to remove invasive carp from a million square kilometres of Australia’s rivers. Some scientists have expressed concern about the potential for the virus to jump species, and the effects of having hundreds of tonnes of dead fish fouling waterways and sapping oxygen from the water. The CSIRO and those planning the release of the virus suggest it is safe and effective.

Despite extensive media reporting giving the impression that the plan is approved to go ahead, the National Carp Control Plan has yet to publish a risk assessment, and is planning to deliver a report in 2018.

Removing well-established invasive species can create unforeseen consequences. These species can play significant roles in food webs, provide shelter for native animals, support ecosystem services, and their sudden death can disrupt ecological processes that are important to native species.

For example, a large amount of time and effort was spent in removing the non-native tamarix (or “salt cedar”) in the southwestern United States, because of the belief it was harming the water table.

Yet, subsequent research has indicated that the negative effects of tamarix have been exaggerated. In some areas, the plant is actually used by large numbers of endangered flycatchers to nest and fledge their young.

A corn bunting perches on a blooming tamarix.
Georgios Alexandris/shutterstock

A science-based solution

In our paper, we highlight a series of considerations that should be addressed before plunging into large-scale invasive species control.

Fundamentally, there must be a demonstrable ecological and social benefit from control or eradication, above and beyond the purely ideological. At first this might seem facile, but invasive species control initiatives are often highly politicised, with science taking a back seat. Given scarce funding for conservation, it is crucial that resources are not squandered on programmes that may not deliver – or could cause environmental damage.

We must avoid assuming that attempting to control invasive species will, by default, solve our environmental problems. This means addressing the full range of human pressures which negatively affect biodiversity. We must also consider how removing an influential invasive species could benefit other invasive species, harm native species through increased predation and competition, or alter ecological processes or habitat.

Comprehensive risk-benefit assessment of invasive species control programs allow decision-makers to proactively avoid, manage or accept these risks.

For example, tonnes of decomposing carp post-virus may cause short-term water quality issues, or the death of native species. Ultimately, however, these risks could be acceptable if the virus is effective, and allows native species a window of opportunity to recover.

The ConversationLarge-scale invasive species control demands careful investigation of the risks and rewards. We hope our paper can provide policy-makers with better guidelines for science-based decision-making.

R. Keller Kopf, Research fellow, Charles Sturt University; Dale Nimmo, ARC DECRA Fellow, Charles Sturt University, and Paul Humphries, Senior lecturer in Ecology, Charles Sturt University

This article was originally published on The Conversation. Read the original article.

Maybe we can, but should we? Deciding whether to bring back extinct species



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Immortalised on a stamp, New Zealand’s stout-legged wren went extinct in the 1990s.
Boris15/www.shutterstock.com

Gwenllian Iacona, The University of Queensland and Iadine Chadès, CSIRO

De-extinction – the science of reviving species that have been lost – has moved from the realm of science-fiction to something that is now nearly feasible. Some types of lost mammals, birds or frogs may soon be able to be revived through de-extinction technologies. The Conversation

But just because we can, does it mean we should? And what might the environmental and conservation impacts be if we did?

Prominent conservation biologist Stuart Pimm has been one of the vocal opponents of de-extinction because, among other concerns,

Without an answer to “where do we put them?” — and to the further question, “what changed in their original habitat that may have contributed to their extinction in the first place?” — efforts to bring back species are a colossal waste.

These are valid concerns, and difficult to consider in light of the many competing factors involved.

We’ve recently outlined a deliberate way to tackle this problem. Our new paper shows that an approach known as “decision science” can help examine the feasibility of de-extinction and its likely impact on existing environmental and species management programs.

Applied to the question of possible de-extinction programs in New Zealand, this approach showed that it would take money away from managing extant (still alive) species, and may lead to other species going extinct.

Solving complex problems

The potential to reverse species extinction is exciting from both a science and a curiosity perspective. But there is also great concern that in the passionate rush to implement new technology, we don’t properly consider environmental, economic and social issues.

Balancing these multiple objectives requires decision makers to understand how various project endpoints relate to all the different project goals.

Decision science methods simplify complex problems into parts that describe the benefit, cost and feasibility of the different possible solutions. They allow for “apples to apples” comparisons to be made about different but essential aspects of the projects being considered.

Decision science in action

When applied to de-extinction projects, decision science lets researchers:

  • compare different possible outcomes of de-extinction approaches
  • better understand future expected costs and benefits, and
  • see impacts of using de-extinction technology on other species that we care about.

New Zealand and New South Wales are home to more than 1,100 threatened species of conservation concern between them.

Over the past decade their management agencies have built on a decision science approach to prioritise their conservation efforts, and increase the number of species they are able to put on the road to recovery.

New Zealand in particular is a prime candidate for considering de-extinction because they have had many recent extinctions, such as the huia.

The New Zealand native bird ‘huia’ went extinct in 1907.
Photographed by Kendrick, J. L. and with thanks from NZ Department of Conservation, Author provided

These lost species fit many of the criteria for species appropriate for de-extinction technologies.

A recent study took the process that was developed to rank New Zealand species according to priority for action, and included 11 possible candidates for de-extinction in the ranking process. These were birds, frogs and plants, including the little bush moa, Waitomo frog and laughing owl.

By applying a decision science process, the authors found that adding these species to the management worklist would reduce their ability to adequately fund up to three times the number of currently managed species, and essentially could lead to additional species going extinct.

The study also showed that private agencies wishing to sponsor the return of resurrected extinct species into the wild, could instead use the money to fund conservation of over eight times as many species, potentially saving them from extinction.

Crucially, this study could not examine the initial costs of using genetic technology to resurrect extinct species, which is unknown but likely to be substantial. If it could have included such costs, de-extinction would have come out as an even less efficient option.

The laughing owl went extinct in New Zealand in 1914.
Photographed by Kendrick, J. L. and with thanks from NZ Department of Conservation, Author provided

Could de-extinction ever be the right option?

The New Zealand example is not a particularly rosy picture, but it may not always be the case that de-extinction is a terrible idea for conservation.

Hypothetically, there are situations where the novelty and excitement of a de-extinct species could act as a “flagship species” and actually attract public interest or funding to a conservation project.

There also is an interesting phenomenon where even just the possibility of having a management action such as de-extinction may change how conservation problems are formulated.

Conservation management currently aims to do the best it can, while operating under the constraint that biodiversity is a non-renewable resource. With this constraint we can apply theory that is used for managing the extraction of non-renewable resources like oil or diamonds to determine the best strategy for management.

However, if extinction was no longer forever, the problem could be considered as one that would be managing a renewable resource, like trees or fish.

Of course, the ability to revive species is nowhere near as simple as regrowing trees, and a species being revived does not necessarily equate to conservation.

But changing the way that conservation managers think about the problem could present conservation gains in addition to losses.

Theoretically, different methods may be used for conservation benefit and there may be different strategies to produce the best outcomes. For example, species that could easily be de-extinct may get less funding attention that the ones for which the de-extinction technology isn’t available, or are too costly to produce.

This research does not advocate for or against de-extinction, rather, it provides strategies to deal with alternatives from the start with a clear representation of the trade-offs.

This work aims to step back and take a realistic look at the implications of new technology, including its costs and its risks, within the context of other conservation actions. Decision theory helps to do just that.

Gwenllian Iacona, Postdoctoral Research Fellow, The University of Queensland and Iadine Chadès, Leader of the Conservation Decisions Team and Senior research scientist, CSIRO

This article was originally published on The Conversation. Read the original article.