Invasive weeds may save Australia's blue-tongue lizards from cane toad poison.
Since the cane toad was introduced to Australia in 1935, it has killed swathes of Australia's native animals including quolls, crocodiles and blue-tongue lizards (Tiliqua scincoides).
Native species that prey on the alien amphibians die because the toads produce a lethal toxin called bufadienolide.
Some blue-tongue lizards in eastern Australia can dine on the cane toads and live, though. Oddly enough, they might owe their immunity to another invasive species.
An ornamental plant native to Madagascar called mother-of-millions (Bryophyllum delagoense) is common in eastern Australia, and has also become part of the lizards' diet. The plants' flowers contain a poison similar to bufadienolide. Rick Shine at the University of Sydney, Australia, suspected that lizards which have already gained immunity to this toxin might be in a better position to withstand the toad toxin too.
His team caught 75 lizards that lived in areas containing either the toad and the ornamental plant, just one of the two, or neither of the toxic invaders. Shine injected toad poison into the lizards, administering a dose high enough to provoke a reaction, but not enough to kill the animal. His team then timed how fast the lizards could swim 50 centimetres.
Blue-tongue lizards from areas containing mother-of-millions were affected to a lesser degree than any others. This was true even for lizards that lived in regions of eastern Australia that contain no cane toads.
"Eastern blue-tongue lizards are able to defend themselves well against cane toads even though they've never actually met one," says Shine.
Mother-of-millions has been recorded in Australia for 70 years or so, suggesting that the lizards have gained tolerance to its toxin rapidly. Blue-tongue lizards create a new generation every two to four years, says study co-author Gregory Brown, also at the University of Sydney.
"It is extremely surprising that one of the lizard populations should genetically change over such a relatively short period of time," says Michael Tyler, an evolutionary biologist at the University of Adelaide, South Australia, who was not involved in the work. "But I am convinced. There is no other explanation I can find."
Showing posts with label cane toads. Show all posts
Showing posts with label cane toads. Show all posts
Thursday, February 9, 2012
Thursday, January 5, 2012
Northern quoll threatened by cane toads
There has been an alarming drop in numbers of the northern quoll with the arrival of the cane toad in its habitat.
VIDEO AND TRANSCRIPT HERE: http://www.abc.net.au/news/2012-01-03/northern-quoll-threatened-by-cane-toads/3757428
Sarah Everingham
VIDEO AND TRANSCRIPT HERE: http://www.abc.net.au/news/2012-01-03/northern-quoll-threatened-by-cane-toads/3757428
Sarah Everingham
Tuesday, September 13, 2011
Cane toads proving highly adaptable - Fast colonisers
They climb, they swim and they're taking over...
September 2011: Scaling cliffs, swimming extraordinary distances and negotiating cave systems - no wonder the cane toads' colonisation of Australia has been so fast.
Kimberley Toad Busters (KTB), a volunteer organisation working to stop the relentless spread of the super-toads which have a negative impact on native wildlife, say it is the toad's hardy nature that has seen such an unprecedented rate of colonisation.
Toads, long thought not to have the ability to climb, to hibernate, to swim well and to remain immersed in water for long periods of time have been shown to do just these things.
Is the cane toad evolving at unprecedented rate?‘The number of toads I've seen and photographed happily climbing up a cliff face, or deep in the bowels of the earth should lay to rest the idea that they are not proficient at these tasks,' said John Cugley, administrative coordinator for KTB and ex-president of the Australian Cavers Association.
‘I wouldn't have believed it if I wasn't there myself,' said Macca, owner of Go-wild eco-canoeing and a KTB volunteer said. ‘I was in the middle of Lake Argyle, some 20 nautical miles from the Eastern shore and low and behold we find a toad happily swimming along. It beggars belief just how long it must have been swimming for to get to that point.'
'This animal will adapt to any climatic conditions'KTB volunteer Dean Goodgame warned: ‘With the toad still holding the record for being the most fertile animal found in the world, it takes no great leap of faith, nor any in depth understanding of biological evolution to realise that this animal will adapt to any of the climatic conditions found in Australia, it really is only a matter of time.'
Lee Scott-Virtue, who founded KTB, said the unique adaptability of the cane toad posed a question: ‘Is the cane toad evolving at a rate far ahead of what science has deemed probable and do scientists appointed by the Federal government really understand the full impact of the cane toad and the work undertaken by community volunteers to mitigate this impact?'
KTB have been recording cane toads breeding and they are well established in areas that defy measures such as ‘fencing'.
http://www.wildlifeextra.com/go/news/cane-toad-australia.html
September 2011: Scaling cliffs, swimming extraordinary distances and negotiating cave systems - no wonder the cane toads' colonisation of Australia has been so fast.
Kimberley Toad Busters (KTB), a volunteer organisation working to stop the relentless spread of the super-toads which have a negative impact on native wildlife, say it is the toad's hardy nature that has seen such an unprecedented rate of colonisation.
Toads, long thought not to have the ability to climb, to hibernate, to swim well and to remain immersed in water for long periods of time have been shown to do just these things.
Is the cane toad evolving at unprecedented rate?‘The number of toads I've seen and photographed happily climbing up a cliff face, or deep in the bowels of the earth should lay to rest the idea that they are not proficient at these tasks,' said John Cugley, administrative coordinator for KTB and ex-president of the Australian Cavers Association.
‘I wouldn't have believed it if I wasn't there myself,' said Macca, owner of Go-wild eco-canoeing and a KTB volunteer said. ‘I was in the middle of Lake Argyle, some 20 nautical miles from the Eastern shore and low and behold we find a toad happily swimming along. It beggars belief just how long it must have been swimming for to get to that point.'
'This animal will adapt to any climatic conditions'KTB volunteer Dean Goodgame warned: ‘With the toad still holding the record for being the most fertile animal found in the world, it takes no great leap of faith, nor any in depth understanding of biological evolution to realise that this animal will adapt to any of the climatic conditions found in Australia, it really is only a matter of time.'
Lee Scott-Virtue, who founded KTB, said the unique adaptability of the cane toad posed a question: ‘Is the cane toad evolving at a rate far ahead of what science has deemed probable and do scientists appointed by the Federal government really understand the full impact of the cane toad and the work undertaken by community volunteers to mitigate this impact?'
KTB have been recording cane toads breeding and they are well established in areas that defy measures such as ‘fencing'.
http://www.wildlifeextra.com/go/news/cane-toad-australia.html
Wednesday, March 9, 2011
Adders, toads and lizards are disappearing from UK
Wednesday, 9 March 2011
By Emma Brennand
Earth News reporter
The native adder is effectively disappearing from our landscape, a study has revealed.
The first nationwide survey of UK amphibian and reptiles has found that Britain's most widespread snake, the adder, is in decline.
Slow worms, common lizards and grass snakes are also becoming less widespread, as are the common toad, common frog and the great crested newt.
The only species found to be increasing its range is the palmate newt.
These startling trends come from a report produced by the Amphibian and Reptile Conservation (ARC) Trust, which has been gathering data on 12 species since 2007.
The trust's National Amphibian and Reptile Recording Scheme (NARRS) has presented its interim findings, which cover the first half of the six-year survey period from 2007 to 2012.
The full survey aims to establish baselines for widespread species - figures against which future status changes can be assessed.
The survey focuses on widespread amphibian and reptile population. These include the great crested, smooth and palmate newts, common toad and frog, common lizard, slow-worm, grass snake and adder, as well as the wall and green lizards and agile frog in Jersey.
The rarest species, such as the great crested newt, already have high levels of protection, but it is strongly suspected that some formerly common species now in decline.
For this reason, the UK government passed legislation in 2007 prioritising the protection of common toads and all UK reptiles.
But this survey suggests that their numbers continue to fall.
Out of approximately 250 square kilometres surveyed, adders were found in about 20.
"Though we suspected that adders were getting much less common, it is very alarming that they turn up in only 7% of reptile surveys nationally," Dr John Wilkinson, Research and Monitoring Officer for the Amphibian and Reptile Conservation Trust, told BBC News.
"Adder occupancy is poor everywhere, making them our rarest widespread reptile by far and in need of serious conservation attention."
Historically, it was believed that adders were most at risk from persecution - people killing the snakes because they are venomous. But the ARC Trust say that their decline may also be caused by development and disturbance.
Under threat
Other widespread amphibians and reptiles also appear to be in trouble.
"There is no single trend as different species are sensitive to different issues," explained Dr Wilkinson.
"Broadly, though, our reptiles and amphibians are doing poorly and adders in particular."
Common frogs are becoming less common in the south of England, particularly in areas which have experienced the most development in recent decades.
And, in the same area of England, the common toad is only half as widespread as the common frog.
"Great crested newts may be much rarer in Scotland than we thought - they haven't turned up in any of our NARRS surveys [there]," said Dr Wilkinson.
Common lizards, thought to occur throughout the UK, were seen rarely in the north and central regions, including Wales. Slow-worms were also found to be scarce in these areas.
Dr Wilkinson believes that this may be because these leg-less lizards are more difficult to find, as they burrow in undergrowth. So a reduced number of sightings may not necessarily reflect a decrease in their population.
Acid-lover
Surprisingly, palmate newt numbers are higher than expected, which might indicate changes in the quality of Britain's ponds.
Unlike many other amphibian species, these small newts thrive in acidic pools that are formed through acid rain fall or agricultural run-off.
The main drive of amphibian and reptile decline is thought to be habitat fragmentation and development.
Conservationists say this is a particular problem for toads, which are more sensitive than frogs to changes in habitat.
The final NARRS report is due to be published in Spring 2014.
See video at: http://news.bbc.co.uk/earth/hi/earth_news/newsid_9405000/9405801.stm
(Submitted by Liz R.)
By Emma Brennand
Earth News reporter
The native adder is effectively disappearing from our landscape, a study has revealed.
The first nationwide survey of UK amphibian and reptiles has found that Britain's most widespread snake, the adder, is in decline.
Slow worms, common lizards and grass snakes are also becoming less widespread, as are the common toad, common frog and the great crested newt.
The only species found to be increasing its range is the palmate newt.
These startling trends come from a report produced by the Amphibian and Reptile Conservation (ARC) Trust, which has been gathering data on 12 species since 2007.
The trust's National Amphibian and Reptile Recording Scheme (NARRS) has presented its interim findings, which cover the first half of the six-year survey period from 2007 to 2012.
The full survey aims to establish baselines for widespread species - figures against which future status changes can be assessed.
The survey focuses on widespread amphibian and reptile population. These include the great crested, smooth and palmate newts, common toad and frog, common lizard, slow-worm, grass snake and adder, as well as the wall and green lizards and agile frog in Jersey.
The rarest species, such as the great crested newt, already have high levels of protection, but it is strongly suspected that some formerly common species now in decline.
For this reason, the UK government passed legislation in 2007 prioritising the protection of common toads and all UK reptiles.
But this survey suggests that their numbers continue to fall.
Out of approximately 250 square kilometres surveyed, adders were found in about 20.
"Though we suspected that adders were getting much less common, it is very alarming that they turn up in only 7% of reptile surveys nationally," Dr John Wilkinson, Research and Monitoring Officer for the Amphibian and Reptile Conservation Trust, told BBC News.
"Adder occupancy is poor everywhere, making them our rarest widespread reptile by far and in need of serious conservation attention."
Historically, it was believed that adders were most at risk from persecution - people killing the snakes because they are venomous. But the ARC Trust say that their decline may also be caused by development and disturbance.
Under threat
Other widespread amphibians and reptiles also appear to be in trouble.
"There is no single trend as different species are sensitive to different issues," explained Dr Wilkinson.
"Broadly, though, our reptiles and amphibians are doing poorly and adders in particular."
Common frogs are becoming less common in the south of England, particularly in areas which have experienced the most development in recent decades.
And, in the same area of England, the common toad is only half as widespread as the common frog.
"Great crested newts may be much rarer in Scotland than we thought - they haven't turned up in any of our NARRS surveys [there]," said Dr Wilkinson.
Common lizards, thought to occur throughout the UK, were seen rarely in the north and central regions, including Wales. Slow-worms were also found to be scarce in these areas.
Dr Wilkinson believes that this may be because these leg-less lizards are more difficult to find, as they burrow in undergrowth. So a reduced number of sightings may not necessarily reflect a decrease in their population.
Acid-lover
Surprisingly, palmate newt numbers are higher than expected, which might indicate changes in the quality of Britain's ponds.
Unlike many other amphibian species, these small newts thrive in acidic pools that are formed through acid rain fall or agricultural run-off.
The main drive of amphibian and reptile decline is thought to be habitat fragmentation and development.
Conservationists say this is a particular problem for toads, which are more sensitive than frogs to changes in habitat.
The final NARRS report is due to be published in Spring 2014.
See video at: http://news.bbc.co.uk/earth/hi/earth_news/newsid_9405000/9405801.stm
(Submitted by Liz R.)
Wednesday, November 17, 2010
New frog species found in hunt for old ones
Richard Black Environment correspondent, BBC News
A search for frogs believed to be extinct has instead led scientists to discover some new ones.
Three species hitherto unknown to science have been found in Colombia.
They include a poison-secreting rocket frog and two toads. All three are tiny and tend to be most active in daytime, which is unusual for amphibians.
However, the same expedition to Colombia failed to find the species it was hoping to rediscover, the Mesopotamia beaked toad.
The disappointment provoked by that non-discovery turned to glee when the conservation scientists came across the three new species.
The 3-4cm red-eyed toad, discovered at an altitude of 2,000m, evoked particular fascination.
"I have never seen a toad with such vibrant red eyes," said Robin Moore from Conservation International, the scientist who set up the rediscovery project.
"This trait is highly unusual for amphibians, and its discovery offers us a terrific opportunity to learn more about how and why it adapted this way."
The other new toad is also tiny - less than 2cm long - with a beak-shaped head that Dr Moore compared to the snout of Montgomery Burns, the villain of The Simpsons TV series.
George Meyer, a long-time Simpsons writer and amphibian enthusiast, commented: "The toad's imperious profile and squinty eyes indeed look like Monty Burns."
The reason why it has not been identified previously is probably because the species skips the tadpole stage, instead producing toadlets that resemble the fallen leaves of the forest floor in which they live.
The third newcomer is a rocket frog, a member of the poison dart family - though not as poisonous as many of its cousins.
The amphibian search, co-ordinated by Conservation International along with the International Union for the Conservation of Nature, began in August and is the first co-ordinated attempt to look for species believed to be extinct.
Expeditions have been mounted in 19 countries in search of 100 lost species.
So far, three have been found: a Mexican salamander not seen since its discovery in 1941, a frog from the Ivory Coast last observed in 1967, and another frog from Democratic Republic of Congo not seen since 1979.
Despite the discoveries and rediscoveries, the team emphasises that overall, the global outlook for amphibians is still bleak.
The remainder of species targeted by the current search have remained undetected, suggesting that they are indeed extinct.
And the latest Red List of Threatened Species, released during the UN biodiversity summit last month, put 41% of amphibians on the danger list, with most of the threats continuing to intensify.
http://www.bbc.co.uk/news/science-environment-11765036
A search for frogs believed to be extinct has instead led scientists to discover some new ones.
Three species hitherto unknown to science have been found in Colombia.
They include a poison-secreting rocket frog and two toads. All three are tiny and tend to be most active in daytime, which is unusual for amphibians.
However, the same expedition to Colombia failed to find the species it was hoping to rediscover, the Mesopotamia beaked toad.
The disappointment provoked by that non-discovery turned to glee when the conservation scientists came across the three new species.
The 3-4cm red-eyed toad, discovered at an altitude of 2,000m, evoked particular fascination.
"I have never seen a toad with such vibrant red eyes," said Robin Moore from Conservation International, the scientist who set up the rediscovery project.
"This trait is highly unusual for amphibians, and its discovery offers us a terrific opportunity to learn more about how and why it adapted this way."
The other new toad is also tiny - less than 2cm long - with a beak-shaped head that Dr Moore compared to the snout of Montgomery Burns, the villain of The Simpsons TV series.
George Meyer, a long-time Simpsons writer and amphibian enthusiast, commented: "The toad's imperious profile and squinty eyes indeed look like Monty Burns."
The reason why it has not been identified previously is probably because the species skips the tadpole stage, instead producing toadlets that resemble the fallen leaves of the forest floor in which they live.
The third newcomer is a rocket frog, a member of the poison dart family - though not as poisonous as many of its cousins.
The amphibian search, co-ordinated by Conservation International along with the International Union for the Conservation of Nature, began in August and is the first co-ordinated attempt to look for species believed to be extinct.
Expeditions have been mounted in 19 countries in search of 100 lost species.
So far, three have been found: a Mexican salamander not seen since its discovery in 1941, a frog from the Ivory Coast last observed in 1967, and another frog from Democratic Republic of Congo not seen since 1979.
Despite the discoveries and rediscoveries, the team emphasises that overall, the global outlook for amphibians is still bleak.
The remainder of species targeted by the current search have remained undetected, suggesting that they are indeed extinct.
And the latest Red List of Threatened Species, released during the UN biodiversity summit last month, put 41% of amphibians on the danger list, with most of the threats continuing to intensify.
http://www.bbc.co.uk/news/science-environment-11765036
New frog species found in hunt for old ones
Richard Black Environment correspondent, BBC News
A search for frogs believed to be extinct has instead led scientists to discover some new ones.
Three species hitherto unknown to science have been found in Colombia.
They include a poison-secreting rocket frog and two toads. All three are tiny and tend to be most active in daytime, which is unusual for amphibians.
However, the same expedition to Colombia failed to find the species it was hoping to rediscover, the Mesopotamia beaked toad.
The disappointment provoked by that non-discovery turned to glee when the conservation scientists came across the three new species.
The 3-4cm red-eyed toad, discovered at an altitude of 2,000m, evoked particular fascination.
"I have never seen a toad with such vibrant red eyes," said Robin Moore from Conservation International, the scientist who set up the rediscovery project.
"This trait is highly unusual for amphibians, and its discovery offers us a terrific opportunity to learn more about how and why it adapted this way."
The other new toad is also tiny - less than 2cm long - with a beak-shaped head that Dr Moore compared to the snout of Montgomery Burns, the villain of The Simpsons TV series.
George Meyer, a long-time Simpsons writer and amphibian enthusiast, commented: "The toad's imperious profile and squinty eyes indeed look like Monty Burns."
The reason why it has not been identified previously is probably because the species skips the tadpole stage, instead producing toadlets that resemble the fallen leaves of the forest floor in which they live.
The third newcomer is a rocket frog, a member of the poison dart family - though not as poisonous as many of its cousins.
The amphibian search, co-ordinated by Conservation International along with the International Union for the Conservation of Nature, began in August and is the first co-ordinated attempt to look for species believed to be extinct.
Expeditions have been mounted in 19 countries in search of 100 lost species.
So far, three have been found: a Mexican salamander not seen since its discovery in 1941, a frog from the Ivory Coast last observed in 1967, and another frog from Democratic Republic of Congo not seen since 1979.
Despite the discoveries and rediscoveries, the team emphasises that overall, the global outlook for amphibians is still bleak.
The remainder of species targeted by the current search have remained undetected, suggesting that they are indeed extinct.
And the latest Red List of Threatened Species, released during the UN biodiversity summit last month, put 41% of amphibians on the danger list, with most of the threats continuing to intensify.
http://www.bbc.co.uk/news/science-environment-11765036
A search for frogs believed to be extinct has instead led scientists to discover some new ones.
Three species hitherto unknown to science have been found in Colombia.
They include a poison-secreting rocket frog and two toads. All three are tiny and tend to be most active in daytime, which is unusual for amphibians.
However, the same expedition to Colombia failed to find the species it was hoping to rediscover, the Mesopotamia beaked toad.
The disappointment provoked by that non-discovery turned to glee when the conservation scientists came across the three new species.
The 3-4cm red-eyed toad, discovered at an altitude of 2,000m, evoked particular fascination.
"I have never seen a toad with such vibrant red eyes," said Robin Moore from Conservation International, the scientist who set up the rediscovery project.
"This trait is highly unusual for amphibians, and its discovery offers us a terrific opportunity to learn more about how and why it adapted this way."
The other new toad is also tiny - less than 2cm long - with a beak-shaped head that Dr Moore compared to the snout of Montgomery Burns, the villain of The Simpsons TV series.
George Meyer, a long-time Simpsons writer and amphibian enthusiast, commented: "The toad's imperious profile and squinty eyes indeed look like Monty Burns."
The reason why it has not been identified previously is probably because the species skips the tadpole stage, instead producing toadlets that resemble the fallen leaves of the forest floor in which they live.
The third newcomer is a rocket frog, a member of the poison dart family - though not as poisonous as many of its cousins.
The amphibian search, co-ordinated by Conservation International along with the International Union for the Conservation of Nature, began in August and is the first co-ordinated attempt to look for species believed to be extinct.
Expeditions have been mounted in 19 countries in search of 100 lost species.
So far, three have been found: a Mexican salamander not seen since its discovery in 1941, a frog from the Ivory Coast last observed in 1967, and another frog from Democratic Republic of Congo not seen since 1979.
Despite the discoveries and rediscoveries, the team emphasises that overall, the global outlook for amphibians is still bleak.
The remainder of species targeted by the current search have remained undetected, suggesting that they are indeed extinct.
And the latest Red List of Threatened Species, released during the UN biodiversity summit last month, put 41% of amphibians on the danger list, with most of the threats continuing to intensify.
http://www.bbc.co.uk/news/science-environment-11765036
Wednesday, October 20, 2010
Cane toads are evolving into super-invaders
Scientists have demonstrated a "runaway evolutionary effect" that is speeding up Australia's cane toad invasion.
This explains why the invasive toads have increased their rate of spread so dramatically, the researchers say.
They found that toads living at the very edge of their range were "super-invaders" - able to move beyond the boundaries of this existing habitat.
And when toads at the frontiers bred, their offspring inherited this ability to move quickly into new territory.
This phenomenon, which scientists have termed the Olympic Village Effect, has been proposed before, since these same scientists observed that the toads at the edge of the range had bigger front legs and stronger back legs - all the better to jump and to invade new areas.
In this study, the researchers tested the effect, essentially setting up a cane toad race.
Radio tags allowed the scientists to track the toads
Dr Ben Phillips from James Cook University in Queensland, Australia collected cane toads from four different populations.
He captured ten toads from the core population in northern Queensland, and ten from each of three populations that were increasingly distant from this point.
He took the toads to a facility in the appropriately named Middle Point near Darwin, where he fitted them with radio tags and then released them. The tags enabled the scientists to follow the toads' progress.
As Dr Phillips expected, toads that were collected from the edge of the range were much faster movers.
All in the genes
To confirm that this increased strength and speed had a genetic basis and could be inherited, Dr Phillips studied a generation further.
He allowed toads from the same population to breed. Then he set up another radio-tagged toad race, this time between these captive-bred offspring.
Toads that had parents from the edge of the range won the dispersal race, revealing that they inherited their speed and strength from their parents.
"It's bad news," Dr Phillips told BBC News. "It means they're getting faster and better at invading new areas."
Even worse, the researchers say, all animal invasions are likely to follow this pattern.
He explained that the faster moving toads even reproduced more quickly. But this could point to a chink in their biological armour.
"They have to be trading something off to do that," he said. "And one of the things we suspect is that they're trading off their immune systems."
Since the bigger, faster toads spread and breed so quickly, they are likely to leave any endemic diseases and parasites behind them because toads that move so quickly are likely to be disease-free.
This could mean that they and their offspring have less natural immunity. If this is the case, it could help scientists develop some sort of biological defence against the toads.
"If you re-introduce [these] parasites at the edge of the range, perhaps you could slow down the invasion," said Dr Phillips.
He and his colleagues plan to study the creatures in more detail in the hope of pinpointing some of these biological weak spots.
Cane toads were introduced to Australia in 1935, to north tropical Queensland to control sugar cane pests. They failed to do this, but succeeded in becoming one of the International Union for the Conservation of Nature's (IUCN) top 100 invasive species.
Their range now extends through most of Queensland and into Australia's Northern Territory.
"They're certainly up there with the worst invasive species," said Dr Phillips. "They're doing well for themselves, you have to give them that."
The work was published in the Journal of Evolutionary Biolog
By Victoria Gill
Science and nature reporter, BBC News
This explains why the invasive toads have increased their rate of spread so dramatically, the researchers say.
They found that toads living at the very edge of their range were "super-invaders" - able to move beyond the boundaries of this existing habitat.
And when toads at the frontiers bred, their offspring inherited this ability to move quickly into new territory.
This phenomenon, which scientists have termed the Olympic Village Effect, has been proposed before, since these same scientists observed that the toads at the edge of the range had bigger front legs and stronger back legs - all the better to jump and to invade new areas.
In this study, the researchers tested the effect, essentially setting up a cane toad race.
Radio tags allowed the scientists to track the toads
Dr Ben Phillips from James Cook University in Queensland, Australia collected cane toads from four different populations.
He captured ten toads from the core population in northern Queensland, and ten from each of three populations that were increasingly distant from this point.
He took the toads to a facility in the appropriately named Middle Point near Darwin, where he fitted them with radio tags and then released them. The tags enabled the scientists to follow the toads' progress.
As Dr Phillips expected, toads that were collected from the edge of the range were much faster movers.
All in the genes
To confirm that this increased strength and speed had a genetic basis and could be inherited, Dr Phillips studied a generation further.
He allowed toads from the same population to breed. Then he set up another radio-tagged toad race, this time between these captive-bred offspring.
Toads that had parents from the edge of the range won the dispersal race, revealing that they inherited their speed and strength from their parents.
"It's bad news," Dr Phillips told BBC News. "It means they're getting faster and better at invading new areas."
Even worse, the researchers say, all animal invasions are likely to follow this pattern.
He explained that the faster moving toads even reproduced more quickly. But this could point to a chink in their biological armour.
"They have to be trading something off to do that," he said. "And one of the things we suspect is that they're trading off their immune systems."
Since the bigger, faster toads spread and breed so quickly, they are likely to leave any endemic diseases and parasites behind them because toads that move so quickly are likely to be disease-free.
This could mean that they and their offspring have less natural immunity. If this is the case, it could help scientists develop some sort of biological defence against the toads.
"If you re-introduce [these] parasites at the edge of the range, perhaps you could slow down the invasion," said Dr Phillips.
He and his colleagues plan to study the creatures in more detail in the hope of pinpointing some of these biological weak spots.
Cane toads were introduced to Australia in 1935, to north tropical Queensland to control sugar cane pests. They failed to do this, but succeeded in becoming one of the International Union for the Conservation of Nature's (IUCN) top 100 invasive species.
Their range now extends through most of Queensland and into Australia's Northern Territory.
"They're certainly up there with the worst invasive species," said Dr Phillips. "They're doing well for themselves, you have to give them that."
The work was published in the Journal of Evolutionary Biolog
By Victoria Gill
Science and nature reporter, BBC News
Cane toads are evolving into super-invaders
Scientists have demonstrated a "runaway evolutionary effect" that is speeding up Australia's cane toad invasion.
This explains why the invasive toads have increased their rate of spread so dramatically, the researchers say.
They found that toads living at the very edge of their range were "super-invaders" - able to move beyond the boundaries of this existing habitat.
And when toads at the frontiers bred, their offspring inherited this ability to move quickly into new territory.
This phenomenon, which scientists have termed the Olympic Village Effect, has been proposed before, since these same scientists observed that the toads at the edge of the range had bigger front legs and stronger back legs - all the better to jump and to invade new areas.
In this study, the researchers tested the effect, essentially setting up a cane toad race.
Radio tags allowed the scientists to track the toads
Dr Ben Phillips from James Cook University in Queensland, Australia collected cane toads from four different populations.
He captured ten toads from the core population in northern Queensland, and ten from each of three populations that were increasingly distant from this point.
He took the toads to a facility in the appropriately named Middle Point near Darwin, where he fitted them with radio tags and then released them. The tags enabled the scientists to follow the toads' progress.
As Dr Phillips expected, toads that were collected from the edge of the range were much faster movers.
All in the genes
To confirm that this increased strength and speed had a genetic basis and could be inherited, Dr Phillips studied a generation further.
He allowed toads from the same population to breed. Then he set up another radio-tagged toad race, this time between these captive-bred offspring.
Toads that had parents from the edge of the range won the dispersal race, revealing that they inherited their speed and strength from their parents.
"It's bad news," Dr Phillips told BBC News. "It means they're getting faster and better at invading new areas."
Even worse, the researchers say, all animal invasions are likely to follow this pattern.
He explained that the faster moving toads even reproduced more quickly. But this could point to a chink in their biological armour.
"They have to be trading something off to do that," he said. "And one of the things we suspect is that they're trading off their immune systems."
Since the bigger, faster toads spread and breed so quickly, they are likely to leave any endemic diseases and parasites behind them because toads that move so quickly are likely to be disease-free.
This could mean that they and their offspring have less natural immunity. If this is the case, it could help scientists develop some sort of biological defence against the toads.
"If you re-introduce [these] parasites at the edge of the range, perhaps you could slow down the invasion," said Dr Phillips.
He and his colleagues plan to study the creatures in more detail in the hope of pinpointing some of these biological weak spots.
Cane toads were introduced to Australia in 1935, to north tropical Queensland to control sugar cane pests. They failed to do this, but succeeded in becoming one of the International Union for the Conservation of Nature's (IUCN) top 100 invasive species.
Their range now extends through most of Queensland and into Australia's Northern Territory.
"They're certainly up there with the worst invasive species," said Dr Phillips. "They're doing well for themselves, you have to give them that."
The work was published in the Journal of Evolutionary Biolog
By Victoria Gill
Science and nature reporter, BBC News
This explains why the invasive toads have increased their rate of spread so dramatically, the researchers say.
They found that toads living at the very edge of their range were "super-invaders" - able to move beyond the boundaries of this existing habitat.
And when toads at the frontiers bred, their offspring inherited this ability to move quickly into new territory.
This phenomenon, which scientists have termed the Olympic Village Effect, has been proposed before, since these same scientists observed that the toads at the edge of the range had bigger front legs and stronger back legs - all the better to jump and to invade new areas.
In this study, the researchers tested the effect, essentially setting up a cane toad race.
Radio tags allowed the scientists to track the toads
Dr Ben Phillips from James Cook University in Queensland, Australia collected cane toads from four different populations.
He captured ten toads from the core population in northern Queensland, and ten from each of three populations that were increasingly distant from this point.
He took the toads to a facility in the appropriately named Middle Point near Darwin, where he fitted them with radio tags and then released them. The tags enabled the scientists to follow the toads' progress.
As Dr Phillips expected, toads that were collected from the edge of the range were much faster movers.
All in the genes
To confirm that this increased strength and speed had a genetic basis and could be inherited, Dr Phillips studied a generation further.
He allowed toads from the same population to breed. Then he set up another radio-tagged toad race, this time between these captive-bred offspring.
Toads that had parents from the edge of the range won the dispersal race, revealing that they inherited their speed and strength from their parents.
"It's bad news," Dr Phillips told BBC News. "It means they're getting faster and better at invading new areas."
Even worse, the researchers say, all animal invasions are likely to follow this pattern.
He explained that the faster moving toads even reproduced more quickly. But this could point to a chink in their biological armour.
"They have to be trading something off to do that," he said. "And one of the things we suspect is that they're trading off their immune systems."
Since the bigger, faster toads spread and breed so quickly, they are likely to leave any endemic diseases and parasites behind them because toads that move so quickly are likely to be disease-free.
This could mean that they and their offspring have less natural immunity. If this is the case, it could help scientists develop some sort of biological defence against the toads.
"If you re-introduce [these] parasites at the edge of the range, perhaps you could slow down the invasion," said Dr Phillips.
He and his colleagues plan to study the creatures in more detail in the hope of pinpointing some of these biological weak spots.
Cane toads were introduced to Australia in 1935, to north tropical Queensland to control sugar cane pests. They failed to do this, but succeeded in becoming one of the International Union for the Conservation of Nature's (IUCN) top 100 invasive species.
Their range now extends through most of Queensland and into Australia's Northern Territory.
"They're certainly up there with the worst invasive species," said Dr Phillips. "They're doing well for themselves, you have to give them that."
The work was published in the Journal of Evolutionary Biolog
By Victoria Gill
Science and nature reporter, BBC News
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