Tasmanian tigers were going extinct before we pushed them over the edge



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Gone since 1936, and ailing since long before that.
Tasmanian Museum and Art Gallery, Author provided

Andrew Pask, University of Melbourne

There’s no doubt that humans killed off the Tasmanian tiger. But a new genetic analysis suggests this species had been on the decline for millennia before humans arrived to drive them to extinction.

The Tasmanian tiger, also known as the thylacine, was unique. It was the largest marsupial predator that survived into recent times. Sadly it was hunted to extinction in the wild, and the last known Tasmanian tiger died in captivity in 1936.

In a paper published in Nature Ecology and Evolution today, my colleagues and I piece together its entire genetic sequence for the first time. It tells us that thylacines’ genetic health had been declining for many millennia before they first encountered human hunters.


Read more: Will we hunt dingoes to the brink like the Tasmanian tiger?


Hounded by hunters.
Tasmanian Museum and Art Gallery, Author provided

Our research also offered the chance to study the origins of the similarity in body shape between the thylacine and dogs. The two are almost identical, despite having last shared a common ancestor more than 160 million years ago – a remarkable example of so-called “convergent evolution”.

Decoding the thylacine genome allowed us to ask the question: if two animals develop an identical body shape, do they also show identical changes in their DNA?

Thylacine secrets

These questions were previously difficult to answer. The age and storage conditions of existing specimens meant that most thylacine specimens have DNA that is highly fragmented into very short segments, which are not suitable for piecing together the entire genome.

We identified a 109-year-old specimen of a young pouch thylacine in the Museums Victoria collection, which had much more intact DNA than other specimens. This gave us enough pieces to put together the entire jigsaw of its genetic makeup.

The preserved young, thylacine with enough DNA to reveal its whole genome.
Museums Victoria, Author provided

Next, we made a detailed comparison of thylacines and dogs to see just how similar they really are. We used digital imaging to compare the thylacine’s skull shape to many other mammals, and found that the thylacine was indeed very similar to various types of dog (especially the wolf and red fox), and quite different from its closest living marsupial relatives such as the numbat, Tasmanian devil, and kangaroos.

Our results confirmed that thylacines and dogs really are the best example of convergent evolution between two distantly related mammal species ever described.

We next asked whether this similarity in body form is reflected by similarity in the genes. To do this, we compared the DNA sequences of thylacine genes with those of dogs and other animals too.

While we found many similarities between thylacines’ and dogs’ genes, they were not significantly more similar than the same genes from other animals with different body shapes, such as Tasmanian devils and cows.

We therefore concluded that whatever the reason why thylacines and dogs’ skulls are so similarly shaped, it is not because evolution is driving their gene sequences to be the same.

Family ties

The thylacine genome also allowed us to deduce its precise position in the marsupial family tree, which has been a controversial topic.

Our analyses showed that the thylacine was at the root of a group called the Dasyuromorphia, which also includes the numbat and Tasmanian devil.

By examining the amount of diversity present in the single thylacine genome, we were able to estimate its effective population size during past millennia. This demographic analysis revealed extremely low genetic diversity, suggesting that if we hadn’t hunted them into extinction the population would be in very poor genetic health, just like today’s Tasmanian devils.

The less diversity you have in your genome, the more susceptible you are to disease, which might be why devils have contracted the facial tumour virus, and certainly why it has been so easily spread. The thylacine would have been at a similar risk of contracting devastating diseases.

The last thylacine alive.
Tasmanian Museum and Art Gallery, Author provided

This loss in population diversity was previously thought to have occurred as a population of thylacines (and devils) became isolated on Tasmania some 15,000 years ago, when the land bridge closed between it and the mainland.

But our analysis suggests that the process actually began much earlier – between 70,000 and 120,000 years ago. This suggests that both the devil and thylacine populations already had very poor genetic health long before the land bridge closed.


Read more: How curiosity can save species from extinction


The ConversationNow that we know the whole genome of the Tasmanian tiger, we know much more about this extinct animal and the unique place it held in Australia’s marsupial family tree. We are expanding our analyses of the genome to determine how it came to look so similar to the dog, and to continue to learn more about the genetics of this unique marsupial apex predator.

Andrew Pask, Associate Professor, University of Melbourne

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

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Even ugly animals can win hearts and dollars to save them from extinction



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It can be easier to raise money to aid animals like these African elephants than species that are more threatened with extinction but get humans less excited.
www.shutterstock.com

Diogo Veríssimo, Johns Hopkins University and Bob Smith, University of Kent

The Earth is home to millions of species, but you wouldn’t know it from the media’s obsession with only a few dozen animals like tigers and gorillas.

This narrow focus makes the most of popular fascination with large and cute creatures. Conservationists take advantage of these nonhuman celebrities to raise awareness about important issues and to seek donations to help save endangered animals. Given the multi-billion-dollar funding shortfall for nature conservation, public support is crucial.

Very popular species attract the most wildlife conservation funding. But what about the Nimba otter shrew, the Cuban greater funnel-eared bat or other threatened yet obscure species? And don’t all imperiled green spaces, not just the homes of snow leopards and orangutans, deserve attention?

Mining activities have destroyed parts of the Nimba otter shrew’s habitat.
Flickr/Julian Bayliss, CC BY-NC-SA

Conventional wisdom counsels sticking with the old approach to fundraising, and conservationists tend to see animals like bats and snakes as lost causes. As conservation scientists, we wanted to discover whether marketing could perhaps rescue these species. If companies can successfully sell mops and other humdrum products, why can’t conservationists raise money to save the unglamorous giant golden mole – even if it looks like a small cushion with a nose poking out of it? We sought the answer to this question by measuring the links between marketing efforts and conservation fundraising success.

Who will save the giant golden mole?
Gary Bronner, CC BY-NC-SA

Two different animals

Our recently published study contrasted online fundraising campaigns by two conservation charities: World Wildlife Fund-US (WWF-US) and the Zoological Society of London (ZSL), through its EDGE of Existence program.

These campaigns are very different. WWF-US raises money for a broad set of projects, addressing global issues from climate change and illegal wildlife trade to forest and ocean conservation. The EDGE campaign we analyzed focuses on saving 100 threatened mammal species.

Given these contrasting approaches, we wanted to see if and when marketing makes a difference. To do this we also had to account for whether the species used for fundraising mattered. This involved measuring an animal’s “appeal,” which depends on lots of factors, such as whether it is cute, large or famous. To see which animals were the most appealing, we showed 850 conservation supporters a random selection of the animal photos featured on the WWF-US and EDGE websites and asked these volunteers to rank the photos.

Let’s first consider WWF-US, which raises money through animal “adoptions.” When people donate, they signal their support for the well-known species. In return they get a stuffed toy, photos of the animals and adoption certificates. But the money WWF-US raised funds projects that benefit more than just the “adopted” animals.

We found two factors influenced WWF-US donors’ choices: the animals’ appeal and the degree of the threat of their extinction. Marketing efforts played no role. No matter how they were described or presented, the most appealing species always drew more donations. This was probably because people already knew and liked them.

The EDGE program raises money in a different way. It supports some universally familiar animals, like the Asian elephant, but many of the species it helps are less appealing to humans, including a variety of rats and bats. Each of these species is shown on their website, so people can click on a link to find out more and then donate.

We found that while people were generally more interested in donating to appealing species, the amount of marketing also made a difference. The animals EDGE actively promoted fared better with potential donors – including some homely ones. Similarly, pitches for the species shown higher up on EDGE’s site got more donors interested in funding the animals’ conservation.


https://cdn.theconversation.com/infographics/105/e3ab8b91f50afedb8ecf0ed8b623bf6f46fc331c/site/index.html

A way to save the rodents

EDGE’s track record suggests that using marketing techniques to raise money for wildlife conservation could increase donations aimed at helping less popular species. To estimate the difference that marketing could make in this regard, we created a mathematical model based on our analysis of the EDGE data. This is an equation that predicts donations based on a species’ appeal (which is fixed) and whether it was promoted by EDGE or shown high up on the website (which we could vary).

Partnering with an EDGE staff member, we then modeled different fundraising scenarios for the 10 most appealing and 10 least appealing animals, as rated by our conservation volunteers. With no marketing effort, our model predicted that the most appealing species would raise 10 times more money than the least appealing animals. This was in line with what we expected and supported the WWF-US strategy.

However, things changed when we modeled the impact from EDGE’s marketing efforts. If the group highlighted the least appealing species by making them prominent on its website, our model predicted a 26-fold increase in donations for those specific animals. This suggests that charities could raise conservation funds for species like bats and rodents, if they tried hard enough.

Our findings indicate that conservationists have more options than they may realize to raise money to aid wildlife.

When can marketing boost donations?

But when should they fundraise for more obscure species? The answer depends on how threatened the animal is, how much help it already gets, the cost of saving it and the chances of the project succeeding. When conservationists focus only on saving elephants, rhinos or other popular species, they often overlook these considerations.

That doesn’t mean WWF-US should end its focus on familiar animals. Since the money it raises funds broad projects that benefit more than just the “adopted” animals, catering to widespread fixations with particular species makes sense.

To be sure, our research did not measure whether marketing efforts pay off by increasing donations overall. But including more kinds of species in a campaign may boost donations – especially for endangered frogs and tarantulas or other underappreciated animals – and even plants.

It might also increase the total number of species in the public eye, highlighting the many ways everyone can help save wildlife.

Conservationists often complain animals that are important to save can get ignored. Our results suggest that they should stop complaining and start marketing.

The ConversationThe graphic containing endangered animals in this article that was originally published on June 21, 2017 was corrected on July 5, 2017. The new version contains the top five animals for EDGE’s fundraising. The old version misidentified and featured the other five in the group’s top 10.

Diogo Veríssimo, David H. Smith Conservation Research Fellow, Johns Hopkins University and Bob Smith, Director, Durrell Institute of Conservation and Ecology, University of Kent

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.

Radical overhaul needed to halt Earth’s sixth great extinction event


Bill Laurance, James Cook University and Paul Ehrlich, Stanford University

Life has existed on Earth for roughly 3.7 billion years. During that time we know of five mass extinction events — dramatic episodes when many, if not most, life forms vanished in a geological heartbeat. The most recent of these was the global calamity that claimed the dinosaurs and myriad other species around 66 million years ago.

Growing numbers of scientists have asserted that our planet might soon see a sixth massive extinction — one driven by the escalating impacts of humanity. Others, such as the Danish economist Bjørn Lomborg, have characterised such claims as ill-informed fearmongering.

We argue emphatically that the jury is in and the debate is over: Earth’s sixth great extinction has arrived.

Collapse of biodiversity

Mass extinctions involve a catastrophic loss of biodiversity, but what many people fail to appreciate is just what “biodiversity” means. A shorthand way of talking about biodiversity is simply to count species. For instance, if a species goes extinct without being replaced, then we are losing biodiversity.

But there’s much more to biodiversity than just species. Within each species there usually are substantial amounts of genetic, demographic, behavioural and geographic variation. Much of this variation involves adaptations to local environmental conditions, increasing the biological fitness of the individual organism and its population.

Natural variation within two species of sea snails. Upper row: Littorina sitkana. Lower row: Littorina obtusata.
Copyright David Reid/Ray Society.

And there’s also an enormous amount of biodiversity that involves interactions among different species and their physical environment.

Many plants rely on animals for pollination and seed dispersal. Competing species adapt to one another, as do predators and their prey. Pathogens and their hosts also interact and evolve together, sometimes with remarkable speed, whereas our internal digestive systems host trillions of helpful, benign or malicious microbes.

Hence, ecosystems themselves are a mélange of different species that are continually competing, combating, cooperating, hiding, fooling, cheating, robbing and consuming one another in a mind-boggling variety of ways.

All of this, then, is biodiversity – from genes to ecosystems and everything in between.

The modern extinction spasm

Cumulative vertebrate species extinctions since 1500 compared to the ‘background’ rate of species losses.
G. Ceballos et al. (2015) Scientific Advances.

No matter how you measure it, a mass extinction has arrived. A 2015 study that one of us (Ehrlich) coauthored used conservative assumptions to estimate the natural, or background rate of species extinctions for various groups of vertebrates. The study then compared these background rates to the pace of species losses since the beginning of the 20th century.

Even assuming conservatively high background rates, species have been disappearing far faster than before. Since 1900, reptiles are vanishing 24 times faster, birds 34 times faster, mammals and fishes about 55 times faster, and amphibians 100 times faster than they have in the past.

For all vertebrate groups together, the average rate of species loss is 53 times higher than the background rate.

Extinction filters

To make matters worse, these modern extinctions ignore the many human-caused species losses before 1900. It has been estimated, for instance, that Polynesians wiped out around 1,800 species of endemic island birds as they colonised the Pacific over the past two millennia.

And long before then, early human hunter-gatherers drove a blitzkrieg of species extinctions — especially of megafauna such as mastodons, moas, elephant birds and giant ground sloths — as they migrated from Africa to the other continents.

In Australia, for instance, the arrival of humans at least 50,000 years ago was soon followed by the disappearance of massive goannas and pythons, predatory kangaroos, the marsupial “lion”, and the hippo-sized Diprotodon among others.

Changes in climate could have contributed, but humans with their hunting and fires were almost certainly the death knell for many of these species.

As a result of these pre-1900 extinctions, most ecosystems worldwide went through an “extinction filter”: the most vulnerable species vanished, leaving relatively more resilient or less conspicuous species behind.

Giant ground sloths such as this elephant-sized Megatherium vanished soon after humans arrived in the New World.
Copyright Catmando.

And it’s the loss of these survivors that we are seeing now. The tally of all species driven to extinction by humans from prehistory to today would be far greater than many people realise.

Vanishing populations

The sixth great extinction is playing out in other ways too, especially in the widespread annihilation of millions (perhaps billions) of animal and plant populations. Just as species can go extinct, so can their individual populations, reducing both the genetic diversity and long-term survival prospects of the species.

For example, the Asian two-horned rhinoceros once ranged widely across Southeast Asia and Indochina. Today it survives only in tiny pockets comprising perhaps 3% of its original geographic range.

Three-quarters of the world’s largest carnivores, including big cats, bears, otters and wolves, are declining in number. Half of these species have lost at least 50% of their former range.

Likewise, except in certain wilderness areas, populations of large, long-lived trees are falling dramatically in abundance.

WWF’s 2016 Living Planet Report summarises long-term trends in over 14,000 populations of more than 3,700 vertebrate species. Its conclusion: in just the last four decades, the population sizes of monitored mammals, birds, fish, amphibians and reptiles have shrunk by an average of 58% worldwide.

And as populations of many species collapse, their crucial ecological functions decline with them, potentially creating ripple effects that can alter entire ecosystems.

Hence, disappearing species can cease to play an ecological role long before they actually go extinct.

Once a widespread and dominating predator, the tiger today is vanishingly rare across most of its former range.
Copyright Matt Gibson

Paying the extinction debt

Everything we know about conservation biology tells us that species whose populations are in freefall are increasingly vulnerable to extinction.

Extinctions rarely happen instantly, but the conspiracy of declining numbers, population fragmentation, inbreeding and reduced genetic variation can lead to a fatal “extinction vortex”. In this sense, our planet is currently accumulating a large extinction debt that must eventually be paid.

And we’re not just talking about losing cute animals; human civilisation relies on biodiversity for its very existence. The plants, animals and microorganisms with which we share the Earth supply us with vital ecosystem services. These include regulating the climate, supplying clean water, limiting floods, running nutrient cycles essential to agriculture and forestry, controlling serious crop pests and carriers of diseases, and providing beauty, spiritual and recreational benefits.

Are we preaching doom? Far from it. What we’re saying, however, is that life on Earth is ultimately a zero-sum game. Humans cannot keep growing in number and consuming ever more land, water and natural resources and expect all to be well.

Limiting harmful climate change has become a catchphrase for battling such maladies. But solutions to the modern extinction crisis must go well beyond this.

We also have to move urgently to slow human population growth, reduce overconsumption and overhunting, save remaining wilderness areas, expand and better protect our nature reserves, invest in conserving critically endangered species, and vote for leaders who make these issues a priority.

Without decisive action, we are likely to hack off vital limbs of the tree of life that could take millions of years to recover.

The Slow Loris, a primitive primate, is a denizen of intact rainforests in southern Asia.
Copyright hkhtt hj

Paul Ehrlich will present a lecture on the current mass extinction, at James Cook University’s Cairns campus on November 10.

The Conversation

Bill Laurance, Distinguished Research Professor and Australian Laureate, James Cook University and Paul Ehrlich, President, Center for Conservation Biology, Bing Professor of Population Studies, Stanford University

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

Some of the world’s strangest species could vanish before they’re discovered


Bill Laurance, James Cook University

Scientists have described around 1.5 million species on Earth – but how many are still out there to be discovered? This is one of the most heated debates in biology. Discounting microbes, plausible estimates range from about half a million to more than 50 million species of unknown animals, plants and fungi.

This biodiversity matters because it could be used to fight human diseases, produce new crops, and offer innovations to help solve the world’s problems.

Why is there so much uncertainty in the numbers? The biggest reason, I argue, is that a lot of biodiversity is surprisingly hard to find or identify. This has profound implications for nature conservation and for our understanding of life on Earth.

Hidden biodiversity

We find new species every day but the organisms that we’re now discovering are often more hidden and more difficult to catch than ever before.

Not surprisingly, the first species to be described scientifically were big and obvious. The earliest naturalists to visit Africa, for instance, could hardly fail to discover zebras, giraffes and elephants.

But recent discoveries are different. For instance, lizard species found today are generally smaller and more often nocturnal than other species of lizard. The tiniest of them, a thumbnail-sized chameleon from Madagascar, was discovered just a few years ago.

Three newly discovered species: (a) a snake-like amphibian from India; (b) the world’s tiniest lizard, and © the only lungless frog species.
B. Scheffers et al. (2014) Trends in Ecology & Evolution

Other unknown species are notoriously difficult to capture. For example, a biologist friend of mine was visiting his mother-in-law in north Queensland when her cat strolled in with an odd-looking animal in its mouth. He wrestled the cat’s dinner away and found that it was a mammal species never before seen in Australia called the prehensile-tailed rat.

Now known to be quite common in the Wet Tropics, this tree-dwelling rat almost never enters conventional wildlife traps. We can thank my mate’s mother-in-law’s cat for the discovery.

Other poorly explored places where new species wait to be discovered include the deep sea, soils and caves. After spending some 1,100 hours digging holes in the ground, biologists stumbled over the first species of Indian caecilian, a primitive, snake-like burrowing amphibian never before seen on the subcontinent.

On a far-flung beach in Alaska, a dead animal that washed ashore just last year turned out to be a completely new species of whale.

A frog species discovered in Borneo is the only frog in the world that completely lacks lungs. It lives in fast-flowing streams that are so oxygen-rich that it can breathe solely through its skin.

And a newly discovered spider in Morocco has evolved to move and escape predators by somersaulting over sand dunes.

The rainforest rooftop

High on the list of places to discover new species include rainforest canopies. In the early 1980s a Smithsonian Institution ecologist, Terry Erwin, used an insecticidal fog on several trees in the Panamanian rainforest and was stunned by his findings. Most of the insects that fell to the ground were entirely new species. Based on quick calculations he estimated that there could be 30 million species of insects residing in the canopies of the world’s rainforests.

Erwin’s conclusions, as it would be expressed today, went viral. In one fell swoop he had increased estimates of global biodiversity at least tenfold. Most biologists today consider his original estimate too high, however some believe he only overestimated a little.

Rainforest canopies are one of the world’s great biological frontiers.
William Laurance

Cryptic species

Beyond species that are difficult to find or catch, a lot of unknown biodiversity is staring us right in the face but we simply can’t see it. For these species, new discoveries are down to advances in molecular genetics. Around 60% of all new organisms described today are so-called “cryptic species” that are nearly indistinguishable from one another.

In recent years, for example, we’ve discovered that Africa has not just one species of elephant but two. Formerly considered different subspecies, genetic analyses reveal that they’re as dissimilar to one another as the Asian elephant is to the extinct woolly mammoth.

Genetic studies have also revealed hidden variation among Africa’s giraffes. Just last year, researchers revealed that what was once considered a single species of giraffe is actually four.

And in Costa Rica, one putative species of butterfly turned out to be at least ten.

Genetic studies have revealed that one apparent species of giraffe is actually four.
William Laurance

Molecular genetics is turning biology on its head in other ways. Organisms we used to think were only distantly related, such as antelopes, dolphins and whales, are practically cousins in evolutionary terms.

Epicentres of unknown species

One last reason why many species are yet to be discovered is that they only live in a small area of the world. Known as “restricted endemics”, these species are geographically concentrated in certain regions such as tropical mountains, islands, and climatically unusual environments.

Most of Earth’s restricted endemics reside in “biodiversity hotspots”, defined by having more than 1,500 locally endemic plant species and less than 30% of their original habitat remaining. Of 35 currently recognised hotspots, half are in the species-rich tropics with the remainder divided among Mediterranean, islands and other ecosystems.

The world’s 35 recognised biodiversity hotspots.
Conservation International

Today, the bulk of new species are being discovered in the biodiversity hotspots. The scary thing is that our recent analyses show that more than half of all hotspots have already lost over 90% of their intact habitat.

Further, most hotspots occur in poorer nations with rapidly-growing populations and escalating social and economic challenges, creating even greater pressures on their already beleaguered ecosystems and species.

Scary implications

Taken collectively, these studies suggest that there’s an enormous wealth of biodiversity on Earth left to discover and that much of it is in danger.

Further, our present knowledge is just scratching the surface. Evolution has had billions of years to create biologically active compounds that can combat human diseases, generate genetic diversity that could save our food crops from disastrous pathogens, and spawn ecological innovations that can inspire marvellous new inventions.

What a tragedy it would be to lose this biodiversity before we have ever had the chance to discover and learn from it.

A new species of Anglerfish discovered this year in the Gulf of Mexico. This bizarre fish has bioluminescent algae in the ‘fishing pole’ above its head to attract prey.
Theodore W. Pietsch, University of Washington

The Conversation

Bill Laurance, Distinguished Research Professor and Australian Laureate, James Cook University

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

Invasive predators are eating the world’s animals to extinction – and the worst is close to home


Tim Doherty, Deakin University; Chris Dickman, University of Sydney; Dale Nimmo, Charles Sturt University, and Euan Ritchie, Deakin University

Invasive species are a threat to wildlife across the globe – and invasive, predatory mammals are particularly damaging.

Our research, recently published in Proceedings of the National Academy of Sciences, shows that these predators – cats, rats and foxes, but also house mice, possums and many others – have contributed to around 60% of bird, mammal and reptile extinctions. The worst offenders are feral cats, contributing to over 60 extinctions.

So how can we stop these mammals eating away at our threatened wildlife?

Counting the cost

Our study revealed that invasive predators are implicated in 87 bird, 45 mammal and 10 reptile extinctions — 58% of these groups’ contemporary extinctions worldwide.

Invasive predators also threaten 596 species classed as vulnerable, endangered or critically endangered on the International Union for the Conservation of Nature Red List. Combined, the affected species include 400 birds, 189 mammals and 149 reptiles.

Twenty-three of the critically endangered species are classed as “possibly extinct”, so the number of extinctions above is likely to be an underestimate.

Until now, these shocking statistics have been unknown, and the heavy toll of invasive predators on native biodiversity grossly underappreciated. Species extinctions attributed to invasive predators include the Hawaiian rail (Zapornia sandwichensis) and Australia’s lesser bilby (Macrotis leucura).

Australia’s lesser bilby, now extinct.

Who are the worst offenders?

We found that three canids (including the red fox and feral dogs), seven members of the weasel family or mustelids (such as stoats), five rodents, two primates, two mongooses, two marsupials and nine species from other families negatively impact threatened species. Some of these species, such as hedgehogs and brushtail possums, don’t immediately spring to mind as predators, yet they are known to prey on many threatened species.

Feral cats threaten the most species overall (430), including 63 that have become extinct. This equates to one-quarter of all bird, mammal and reptile extinctions – making the feral cat arguably the most damaging invasive species for animal biodiversity worldwide.

Five species of introduced rodent collectively threaten 420 species, including 75 extinctions. While we didn’t separate out the impacts of individual rodent species, previous work shows that black rats (Rattus rattus) threaten the greatest number of species, followed by brown rats (R. norvegicus) and Pacific rats (R. exulans).

The humble house mouse (Mus musculus) is another interesting case. Despite their small size, house mice have been recorded eating live chicks of albatrosses, petrels and shearwaters.

Other predators that threaten large numbers of species are the domestic dog (Canis familiaris), pig (Sus scrofa), small Indian mongoose (Herpestes auropunctatus), red fox (Vulpes vulpes) and stoat (Mustela erminea).

Invasive mammalian predators (clockwise from top left): feral dog, house mouse, stoat, feral pig, feral cat, brushtail possum, black rat, small Indian mongoose and red fox (centre).
Clockwise from top-left: Andrey flickr CC BY 2.0 https://flic.kr/p/4M2E7y; Richard Adams flickr CC BY 2.0 https://flic.kr/p/7U19v9; Mark Kilner flickr CC BY-NC-SA 2.0 https://flic.kr/p/4D6LPe; CSIRO CC BY 3.0 http://www.scienceimage.csiro.au/image/1515; T. Doherty; Toby Hudson CC BY-SA 3.0 https://commons.wikimedia.org/wiki/File:BrushtailPossum.jpg; CSIRO CC BY 3.0 http://www.scienceimage.csiro.au/image/10564; J.M.Garg CC BY-SA 3.0 https://commons.wikimedia.org/wiki/File:Herpestes_edwardsii_at_Hyderaba.jpg; Harley Kingston CC BY 2.0 https://flic.kr/p/ceWFr7 (centre).

Island species most at risk

Species found only on islands (insular endemics) account for 81% of the threatened species at risk from predators.

The isolation of many islands and a lack of natural predators mean that insular species are often naive about new predators and lack appropriate defensive responses. This makes them highly vulnerable to being eaten and in turn suffering rapid population decline or, worse, extinction. The high extinction rates of ground-dwelling birds in Hawaii and New Zealand — both of which lack native mammalian predators — are well-known examples.

Accordingly, the regions where the predators threatened the greatest number of species were all dominated by islands – Central America and the Caribbean, islands of the Pacific, the Madagascar region, New Zealand and Hawaii.

Conversely, the continental regions of North and South America, Europe, Africa and Asia contain comparatively few species threatened by invasive predators. While Australia is a continent, it is also an island, where large numbers of native birds and mammals are threatened by cats and foxes.

Along with feral cats, red foxes have devastated native mammals in Australia.
Tom Rayner

Managing menacing mammals

Understanding and mitigating the impact of invasive mammal predators is essential for reducing the rate of global biodiversity loss.

Because most of the threatened species studied here live on islands, managing invasive predators on islands should be a global conservation priority. Invasive predators occur on hundreds of islands and predator control and eradication are costly exercises. Thus, it is important to prioritise island eradications based on feasibility, cost, likelihood of success and potential benefits.

On continents or large islands where eradications are difficult, other approaches are needed. This includes predator-proof fencing, top-predator restoration and conservation, lethal control, and maintenance of habitat structure.

Despite the shocking statistics we have revealed, there remain many unknowns. For example, only around 40% of reptile species have been assessed for the Red List, compared to 99% for birds and mammals. Very little is known about the impact of invasive predators on invertebrate species.

We expect that the number of species affected by invasive predators will climb as more knowledge becomes available.


This article was co-authored by Al Glen from Landcare Research, New Zealand.

The Conversation

Tim Doherty, Research Fellow, Deakin University; Chris Dickman, Professor in Terrestrial Ecology, University of Sydney; Dale Nimmo, Lecturer in Ecology, Charles Sturt University, and Euan Ritchie, Senior Lecturer in Ecology, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University

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