3005. Florida's Invasive Pythons Are Mostly Cousins

By Science Daily, August 25, 2018

A new genetic analysis of invasive pythons captured across South Florida finds the big constrictors are closely related to one another. In fact, most of them are genetically related as first or second cousins, according to a study by wildlife genetics experts at the U.S. Geological Survey.

The study also found that at least a few of the snakes in the invasive South Florida population are not 100 percent Burmese pythons. Instead, the genetic evidence shows at least 13 snakes out of about 400 studied are a cross between two separate species: Burmese pythons, which mostly inhabit wetlands, and Indian pythons, which prefer higher ground. The interbreeding between Burmese and Indian pythons probably took place before the animals became established in the South Florida environment, and may have given them greater adaptability in their new habitats.

The South Florida pythons spring from a tangled family tree, with consequences for the species' future spread that are hard to predict, the USGS scientists said.

"The snakes in South Florida are physically identifiable as Burmese pythons, but genetically, there seems to be a different, more complicated story," said Margaret Hunter, a USGS research geneticist and lead author on the study published in the journal Ecology and Evolution.

Burmese pythons have been reproducing in the Everglades since the 1980s, and have caused important environmental changes including the decline of small-mammal populations in South Florida.

The researchers analyzed tail tissue from about 400 Burmese pythons captured across a wide area, from southwest Florida and the Big Cypress National Preserve to the Everglades, southeast Miami-Dade County and the Florida Keys, between 2001 and 2012.

The researchers looked at nuclear DNA, which contains genetic material from both parents, to determine how much each animal had in common with others in the population. To express family relationships in statistical terms, they used a common type of calculation known as a relatedness value. 

For all snakes in the study, the average relatedness value was about midway between first and second cousins. That close kinship means the population as a whole is experiencing inbreeding, the researchers concluded.

When the researchers tested genetic material from a different part of the snakes' cells-mitochondrial DNA, inherited solely from the mother-they were surprised to find genetic signatures from the Indian python in 13 snakes.

Sometimes interbreeding between related species "can lead to hybrid vigor, that is, the best traits of two species are passed onto their offspring," Hunter said. "Hybrid vigor can potentially lead to a better ability to adapt to environmental stressors and changes. In an invasive population like the Burmese pythons in South Florida, this could result in a broader or more rapid distribution."

In the wild, related species typically avoid interbreeding by using different habitats. In their native Asia, Burmese pythons prefer wet habitats, while Indian pythons tend to stick to drier ones. In previous studies, scientists have observed South Florida's Burmese pythons in both wet and dry habitat types.

"Our ability to detect Burmese pythons in the Greater Everglades has been limited by their effective camouflage and secretive behavior," said Kristen Hart, a USGS research ecologist and a co-author on the study. "By using genetic tools and techniques and continuing to monitor their movement patterns, we have been able to gain a better understanding of their habitat preferences and resource use. The new information in this study will help scientists and wildlife managers better understand these invasive predators' capacity to adapt to new environments."

Journal Reference:
Margaret E. Hunter, Nathan A. Johnson, Brian J. Smith, Michelle C. Davis, John S. S. Butterfield, Ray W. Snow, Kristen M. Hart. Cytonuclear discordance in the Florida Everglades invasive Burmese python (Python bivittatus) population reveals possible hybridization with the Indian python (P. molurus). Ecology and Evolution, 2018; DOI: 10.1002/ece3.4423

1952. Let's Give Feral Cats Their Citizenship

By Arian Wallach and Daniel Ramp, The Conversation, July 28, 2015

Millions of feral cats have gone wild in Australia 

There’s been a lot of talk about killing feral cats, with the government’s recently announced war on cats setting the goal of killing two million by 2020.

On The Conversation last week, Katherine Moseby and John Read explained several different ways to control feral cats, including baiting.

But we would like to offer a different idea: let’s embrace cats as part of Australia’s environment. We could even rename them “Australian wildcats”. Let us explain.

Embracing cats would primarily entail ending our practice of killing cats. This would have many advantages.

It would benefit the cats, because they would no longer endure our increasingly creative methods of ending their lives. We would also benefit greatly by unburdening ourselves of the task of causing suffering and death to cats. But what may seem counterintuitive is that leaving cats alone can also benefit Australia’s threatened native species.

Being kind to cats can help native wildlife

Many people love cats and do not want them harmed. Advocates for nonlethal approaches to control cat numbers often recommend sterilisation, but this idea is based on the mistaken assumption that feral cats are originating from our homes.

Many cats do live among us, but most now exist in a completely wild state, including in the middle of the driest of deserts and the lushest of rainforests. Sterilisation can help reduce the number of house cats without a home, but it will not benefit wildlife away from cities. We need to move beyond thinking about cats as either wards or enemies.

Several small and medium-sized native species have declined and gone extinct, partially due to non-native cats and foxes. Several decades of conservation efforts have therefore focused on killing these predators, a sufficiently long process to learn that this approach is not working.

Even highly coordinated and intensive eradication programs backfire. This can happen in two ways. Killing cats, even two million of them, can inadvertently increase cat numbers by enabling more cats to immigrate into vacant territories. Conversely, cat eradication can cause population booms of other species (such as rabbits and rats) and result in further harm.

Ecosystems are notoriously, and wonderfully, complex things. They are comprised of dense networks of interactions that bind the fate of species to one another. Cats have become deeply entangled in this web of life. Attempting to remove cats from Australian ecosystems will not be a clean and painless surgery, and it will not heal the patient.

Coexistence with cats is possible

For many years introduced species were believed to be harmful because natives have not evolved the traits to hold their own against them. But we are learning that species can be surprisingly adaptable.

For example, when native Australian predators first encounter cane toads they often mistake them for just another familiar amphibian and readily eat them, unaware of the toad’s defence – toxic glands on their backs.

Eventually predator populations recover as they learn how to eat them, they learn not to eat them, or they adapt to the toxin. Such a remarkable recovery has not occurred for many of the native prey species threatened by cat and fox predation, and not because they are slow. Their difficulty, instead, lies with the very actions we are taking to save them.

The number of cats and their influence on other wildlife are a function of ecological context. Major forces that influence the ability of prey to coexist with cats include vegetation cover and larger predators. Grazing and fire can reduce vegetation cover and make it harder for prey animals to escape. Significantly, larger predators, such as dingoes, are a major threat to cats.

Dingoes do more than just kill cats, they communicate with them and influence their behaviour. Cats fear dingoes, and stay away from areas frequented by them. They also avoid hunting when dingoes are most active. This creates areas of safety for the prey of cats. Our poisons and traps kill cats, but tell them nothing.

From foxes to cats

The war on cats is ultimately a consequence of our failed war on foxes.

Foxes have long been held as Australia’s primary environmental villain. They are also easier to kill, because they more readily scavenge. Meat baits laced with 1080 poison are used extensively in conservation programs.

This inhumane poison kills foxes and dingoes in untold numbers, and enables cats to breed up and move with impunity across the landscape.

For example, a major poison-baiting campaign did help recover endangered woylies for a time, but eventually the loss of foxes and dingoes caused cats to take over and the newly recovered population collapsed.

All Australian conservation programs dedicated to restoring small native species on the mainland continue to use 1080. National parks use it. Pastoral stations use it. Councils use it.

It is time to go cold turkey.

Embracing Australia’s wildlife without prejudice

Cats have become an integral part of Australia’s wildlife and beauty. Many native species successfully coexist with cats, especially when we leave predators alone.

Australian wildcats probably provide the same ecological functions as they do in their native ranges, such as suppressing population irruptions of their prey. Killing cats achieves only one outcome with consistency: it produces dead cats.

However, the aim of conservation is not to generate an ever increasing body count, but to guide human behaviour to enable the rest of the Earth’s species to flourish. 

Embracing cats is a paradigm shift. It means embracing the entirety of Australia’s modern ecosystems - native and feral - and letting go of the past.

It is time to accept these immigrants as Australian citizens.

1808. Invasive Species: The Snake That’s Eating Florida

By Clyde Haberman, The New York Times, April 5, 2015

Burmese python consuming a deer it killed in Florida

Ever since a serpent enticed Eve to munch on that forbidden fruit in the Garden of Eden, relations between humans and snakes have been at best strained. But at least the gullible Eve and her mate had to cope with just the one snake. In South Florida, wildlife officials have struggled for years with tens of thousands of the creatures: specifically, a species known as the Burmese python, an interloper from Southeast Asia that has taken up what looks like permanent residence in Everglades National Park and other areas of the state.

This is some snake. At full maturity, a Burmese python routinely reaches lengths of 12 feet or more. Twenty-footers weighing 250 pounds are not unheard-of. The pythons are prodigious breeders, with voracious appetites to match. They are believed to have eaten their way through the Everglades, bringing about startling changes in the ecosystem. 

Some mammals native to those marshes, like foxes and rabbits, seem to have disappeared, researchers say. Other species — among them raccoons, deer, opossums and bobcats — are close to being wiped out. Pythons that migrated from the mainland to Key Largo have put indigenous wood rats in mortal peril.

Retro Report, a series of video documentaries exploring major news stories of the past, trains its lens on the dawning realization more than a dozen years ago that the Burmese python had the potential to alter Florida’s environment far more than people realized. But the issue is really greater than one breed of Asian snakes that ran wild after being imported into the country as pets. The United States is awash in invasive species exacting a heavy toll on native wildlife and vegetation. The list of intruders is long. To name but a few, they include Argentine tegus, large lizards that feast on sea turtle eggs; venomous lionfish from Asia, which prey on local varieties of fish; Nile monitor lizards from Africa, which love to eat frogs and crocodile eggs; zebra mussels from Russia, which harm waterways and damage water treatment plants; and Asian carp, which threaten the environmental balance of the Great Lakes.

Florida draws much of the attention because its swamps and tropical climate provide splendid shelter for all sorts of creatures that are not supposed to call this country home. The state, as more than one person has observed, is the Ellis Island of exotic species.

Like many animals previously unknown on the North American continent, the Burmese python arrived through the pet trade. (Language purists might reasonably ask if it is fair to describe these snakes as invasive. It is not as if they barged in on their own. People created the problem.) At least two million constrictor snakes — boas, anacondas and pythons — are believed to have been imported since the 1970s, part of a lucrative market for exotic species. Miami is an important hub for this trafficking.

One issue with Burmese pythons is that people cavalierly bought them when they were maybe a foot long. In short order, those little fellows grew to eight feet, 12 feet, 16 feet. Talk about buyer’s remorse. Unable to deal with these giants, owners often dumped them wherever seemed feasible. One way or another, snakes in South Florida found their way to the Everglades. There, they multiplied, again and again. Recent estimates by the National Park Service put the numbers there as high as 100,000. Walter E. Meshaka Jr. was the supervisory curator for national parks in southern Florida from 1995 to 2000. Even back then, Mr. Meshaka told Retro Report, the question was whether the python population would explode. And, he said, “Lo and behold, it did.”

Quite possibly, some experts in the field suggest, the local wildlife has been slow to appreciate the menace. “It’s probably a safe assumption that things like raccoons and possums probably don’t associate snakes with being something that really is a major threat to them,” Michael E. Dorcas, a herpetologist at Davidson College in North Carolina, said in a 2012 interview with Yale Environment 360, an online publication of the Yale School of Forestry and Environmental Studies. “Because,” Mr. Dorcas continued, “there really hasn’t been a snake big enough to eat a raccoon living in Florida for about 18 million years.”

While the python is more of a direct threat to native birds and animals than to people, attacks on humans are not unknown. One of the more horrifying instances occurred in 2009 when a 2-year-old girl in northern Florida was strangled by a Burmese python that belonged to her mother’s boyfriend. This eight-foot snake, which was later found to have been severely malnourished, broke free, coiled itself around the girl and squeezed her to death. Both the mother and the boyfriend were held responsible — convicted of manslaughter and sentenced to 12 years in prison.

The authorities in Florida have tried getting the unwelcome reptile population under control, but to little avail. A couple of years ago, they organized a Python Challenge, a come-one, come-all snake hunt on state land near Everglades National Park. It put barely a dent in the python population; no more than a few dozen of them were captured. Pythons have shown themselves to be masters of stealth. In a rather glum assessment, the United States Fish and Wildlife Service said in a statement last month that “scientists have not found any way of eradicating invasive constrictor snakes once they become established in the wild.” Some experts say the best hope to kill these creatures en masse may be a deep and prolonged freeze in southern Florida. Of course, everyone would then worry about the devastating effect on the state’s citrus crop.

Should other sections of the country start fretting about possible python incursions of their own? Yes, say some scientists who predict that, in coming decades, the invaders could slither their way across one-third of the United States — perhaps even reaching New York City by 2100. Other experts, however, wave off such fears as overblown.

The Obama administration has chosen to take a stand. Three years ago, the Fish and Wildlife Service banned imports and interstate transport of four species of constrictors: Burmese pythons, yellow anacondas and northern and southern African pythons. Last month, the prohibition was extended to four other species: reticulated pythons, DeSchauensee’s anacondas, green anacondas and Beni anacondas. (Boa constrictors, an important component of the pet snake trade, were spared a ban.) Not surprisingly, reptile sellers and breeders are not happy with the restrictions, with slippery slopesters among them warning that all kinds of animals, including more familiar household pets, could become the next government target.

Effective or not, the import bans are a recognition that some species labeled invaders were invited in by humans. It is a reality reminiscent of a famous line from no less than a swamp creature: the possum Pogo, whose name was the title of Walt Kelly’s long-running comic strip. Referring to unwelcome environmental change, Pogo said, “We have met the enemy and he is us.”

1728. Cats and Foxes Imported by European Colonists Are Killing Off Native Mammals in Australia, Study Finds

By The Associated Press, The New York Times, February 9, 2015

There are an estimated 15 million feral cats in Australia

Australia’s mammals are going extinct at an unusually high rate, and a new study says the main culprits are cats and foxes brought to the continent by European settlers. The study, published by the Proceedings of the National Academy of Sciences on Monday, shows that more than 10 percent of the land mammal species endemic to Australia have been wiped out since European settlement began in 1788. That rate has long been a source of puzzlement since sparsely populated Australia would seem to be a paradisiacal haven for animals. But the researchers found that much of the species’ decline coincided with the introduction of two animals: the feral cat, which sailors brought aboard ships to keep rats at bay, and red foxes, brought for hunting. As it turned out, both species hunted a little too well and they spread rapidly. “We knew it was bad, but I think our tallies were much worse than previously thought,” said one of the study’s authors, Prof. John Woinarski of Charles Darwin University.

1511. Decades of Herbicide Use Yield "Weeds" that Do Not Respond to Herbicides: The Case of Amaranthus Palmeri

By Michael Wines, The New York Times, August 11, 2014

Glyphosate resistant Palmer Amaranth, photo by FireFlyForest.com

WHEATFIELD, Ind. — The Terminator — that relentless, seemingly indestructible villain of the 1980s action movie — is back. And he is living amid the soybeans at Harper Brothers Farms.

About 100 miles northwest of Indianapolis, amid 8,000 lush acres farmed by Dave Harper, his brother Mike and their sons, the Arnold Schwarzenegger of weeds refuses to die. Three growing seasons after surfacing in a single field, it is a daily presence in a quarter of the Harper spread and has a foothold in a third more. Its oval leaves and spindly seed heads blanket roadsides and jut above orderly soybean rows like skyscrapers poking through cloud banks. It shrugs off extreme drought and heat. At up to six inches in diameter, its stalk is thick enough to damage farm equipment.

“You swear that you killed it,” said Scott Harper, Dave Harper’s son and the farm’s 28-year-old resident weed expert. “And then it gets a little green on it, and it comes right back.”

Botanists call the weed palmer amaranth. But perhaps the most fitting, if less known, name is carelessweed. In barely a decade, it has devastated Southern cotton farms and is poised to wreak havoc in the Midwest — all because farmers got careless.

After Monsanto began selling crops genetically engineered to resist glyphosate in the 1990s, the herbicide’s use soared. Farmers who once juggled an array of herbicides — what killed weeds in a cotton field might kill cornstalks in a cornfield — suddenly had a single herbicide that could be applied to almost all major crops without harming them.

There were even environmental benefits: Farmers relied less on other, more dangerous weed killers. And they abandoned techniques like tilling that discouraged weed growth, but hastened erosion and moisture loss.

But constantly dousing crops in glyphosate exacted a price. Weeds with glyphosate-resisting genetic mutations appeared faster and more often — 16 types of weed so far in the United States. A 2012 survey concluded that glyphosate-resistant weeds had infested enough acreage of American farmland to cover a plot nearly as big as Oregon, and that the total infestation had grown 51 percent in one year. Glyphosate-resistant palmers first surfaced in 2005, in a field in Macon County, Ga. Nine years later, they are in at least 24 states.

“There’s no substantive argument about whether the problem’s gotten far worse in this era of genetically resistant crops,” said Charles Benbrook, a professor and pesticide expert at Washington State University. “The advent of herbicide-tolerant crops made it possible for farmers to load up so much herbicide on one crop that it was inevitable that it would develop resistance.”

Now farmers are going back to older techniques to control weeds, using more varieties of herbicides, resuming tilling — and worse.

Palmer amaranth is the prime example. Consider the cotton fields that blanket many Southern farms: Without glyphosate, almost no herbicides can kill the weed without also damaging cotton plants. Some farmers have mowed their crops to keep palmer seeds from maturing. In 2009, Georgia spent $11 million to send laborers into a million acres of cotton fields to pull palmers out by hand.

For many farmers, including the Harpers, manual labor has become a last resort in the battle against carelessweed.

“I consider myself a Roundup baby, and it was great,” Scott Harper said. “You didn’t have to think about anything. And now we get this weed that flips everything on its head.”

The Harpers’ 2,500-acre soybean crop is an object lesson in palmer’s adaptability and how far farmers must go just to keep it in check.

Palmer amaranths seem as if they were designed by nature to outwit herbicides and farmers. Unlike many weeds, it has male and female versions, increasing genetic diversity — and the chances of a herbicide-resistant mutation — in each new seed. And each plant is astonishingly prolific, producing up to 200,000 seeds in an average field, said Dave Mortensen, a professor of weed and plant ecology at Pennsylvania State University.

“If one out of millions or billions of seeds contains a unique trait that confers resistance to herbicide,” he said, “it doesn’t take long when a plant is that fecund for it to become the dominant gene.”

William G. Johnson, a Purdue University professor of botany and plant pathology, said the weed probably arrived at the Harpers’ farm in typical fashion: in manure, purchased as fertilizer, from cows that ate cottonseed — and, inadvertently, palmer seeds.

The Harpers initially mistook the weed for waterhemp, a close relative. Before they learned otherwise, combines had already harvested fields containing mature palmer seed pods and had spread the seed far and wide.

A glyphosate-resistant palmer is a mighty beast indeed. Its seeds can germinate any time during the growing season, so herbicide sprayed in April is useless against a palmer that appears in July. Once sprouted, palmer amaranth can grow more than two inches a day. Once it exceeds four inches, even herbicides for which it lacks resistance begin to lose their effectiveness.

The Harpers have kept palmers at bay in their 5,500 acres of corn by spraying dicamba, a weed killer that is benign to corn. Soybeans are a different matter.

Last year, the Harpers sprayed palmer-infested fields several times with glyphosate and two other herbicides, pushing herbicide costs to $80 an acre from $15. About eight in 10 palmers died. The rest wilted for a couple of weeks, then resumed growing.

This year, they are trying a different chemical cocktail that raises herbicide costs only to $45 an acre. Their big gun, a herbicide that blocks palmers from synthesizing amino acids, was sprayed on July 3, the first of two applications allowed each summer.

“I came back from the Fourth of July weekend, and they looked dead,” Mr. Harper said. “I said, ‘I think we smoked ’em.’ My dad says, ‘Awesome.’ ” He paused. “Ten days later, there’s green coming all over them again.”

Should the second herbicide application fail, Mr. Harper said, he is unsure what to do next.

More broadly, experts in glyphosate’s travails — farmers, scientists, regulators, the herbicide industry, environmentalists — feel much the same way.

The industry has readied a new barrage of genetically engineered crops that tolerate other weed killers. The Environmental Protection Agency is set to approve plans by Dow AgroSciences to sell soybean seeds that tolerate not only glyphosate, but a much older herbicide, 2,4-D, and a third widely used herbicide, glufosinate. Monsanto hopes to market soybeans and cotton next year that resist dicamba.

Dr. Mortensen and others say the companies are simply repeating the history that made palmers resistant to glyphosate. He says natural solutions, like planting what are known as cover crops that keep light from reaching germinating palmers, may cost more but are also effective.

Mr. Harper said he believes Dr. Mortensen is right. He also said he cannot wait for Monsanto and Dow to begin hawking their new soybeans anyway.

“I’m not stupid. I know you can only ride a pony so far,” he said. “It’ll probably take another 10 years before palmer becomes a real big problem again. But that just brought me 10 years I didn’t have.”