Posts Tagged ‘extinction’

Aylin Woodward

The phrase “mass extinction” typically conjures images of the asteroid crash that led to the twilight of the dinosaurs.

Upon impact, that 6-mile-wide space rock caused a tsunami in the Atlantic Ocean, along with earthquakes and landslides up and down what is now the Americas. A heat pulse baked the Earth, and the Tyrannosaurus rex and its compatriots died out, along with 75% of the planet’s species.

Although it may not be obvious, another devastating mass extinction event is taking place today — the sixth of its kind in Earth’s history. The trend is hitting global fauna on multiple fronts, as hotter oceans, deforestation, and climate change drive animal populations to extinction in unprecedented numbers.

A 2017 study found that animal species around the world are experiencing a “biological annihilation” and that our current “mass extinction episode has proceeded further than most assume.”

Here are 12 signs that the planet is in the midst of the sixth mass extinction, and why human activity is primarily to blame.

Insects are dying off at record rates. Roughly 40% of the world’s insect species are in decline.

2019 study found that the total mass of all insects on the planets is decreasing by 2.5% per year.

If that trend continues unabated, the Earth may not have any insects at all by 2119.

“In 10 years you will have a quarter less, in 50 years only half left, and in 100 years you will have none,” Francisco Sánchez-Bayo, a coauthor of the study, told The Guardian.

That’s a major problem, because insects like bees, butterflies, and other pollinators perform a crucial role in fruit, vegetable, and nut production. Plus, bugs are food sources for many bird, fish, and mammal species — some of which humans rely on for food.

Earth appears to be undergoing a process of “biological annihilation.” As much as half of the total number of animal individuals that once shared the Earth with humans are already gone.

A 2017 study looked at all animal populations across the planet (not just insects) by examining 27,600 vertebrate species — about half of the overall total that we know exist. They found that more than 30% of them are in decline.

Some species are facing total collapse, while certain local populations of others are going extinct in specific areas. That’s still cause for alarm, since the study authors said these localized population extinctions are a “prelude to species extinctions.”

So even declines in animal populations that aren’t yet categorized as endangered is a worrisome sign.

More than 26,500 of the world’s species are threatened with extinction, and that number is expected to keep going up.

According to the International Union for Conservation of Nature Red List, more than 27% of all assessed species on the planet are threatened with extinction. Currently, 40% of the planet’s amphibians, 25% of its mammals, and 33% of its coral reefs are threatened.

The IUCN predicts that 99.9% of critically endangered species and 67% of endangered species will be lost within the next 100 years.

A 2015 study that examined bird, reptile, amphibian, and mammal species concluded that the average rate of extinction over the last century is up to 100 times as high as normal.

Elizabeth Kolbert, author of the book “The Sixth Extinction,” told National Geographic that the outlook from that study is dire; it means 75% of animal species could be extinct within a few human lifetimes.

In roughly 50 years, 1,700 species of amphibians, birds, and mammals will face a higher risk of extinction because their natural habitats are shrinking.

By 2070, 1,700 species will lose 30% to 50% of their present habitat ranges thanks to human land use, a 2019 study found. Specifically, 886 species of amphibians, 436 species of birds, and 376 species of mammals will be affected and consequently will be at more risk of extinction.

Logging and deforestation of the Amazon rainforest is of particular concern.

Roughly 17% of the Amazon has been destroyed in the past five decades, mostly because humans have cut down vegetation to open land for cattle ranching, according to the World Wildlife Fund. Some 80% of the world’s species can be found in tropical rainforests like the Amazon, including the critically endangered Amur leopard. Even deforestation in a small area can cause an animal to go extinct, since some species live only in small, isolated areas.

Every year, more than 18 million acres of forest disappear worldwide. That’s about 27 soccer fields’ worth every minute.

In addition to putting animals at risk, deforestation eliminates tree cover that helps absorb atmospheric carbon dioxide. Trees trap that gas, which contributes to global warming, so fewer trees means more CO2 in the atmosphere, which leads the planet to heat up.


In the next 50 years, humans will drive so many mammal species to extinction that Earth’s evolutionary diversity won’t recover for some 3 million years, one study said.

The scientists behind that study, which was published in 2018, concluded that after that loss, our planet will need between 3 million and 5 million years in a best-case scenario to get back to the level of biodiversity we have on Earth today.

Returning the planet’s biodiversity to the state it was in before modern humans evolved would take even longer — up to 7 million years.

Alien species are a major driver of species extinction.

A study published earlier this month found that alien species are a primary driver of recent animal and plant extinctions. An alien species is the term for any kind of animal, plant, fungus, or bacteria that isn’t native to an ecosystem. Some can be invasive, meaning they cause harm to the environment to which they’re introduced.

Many invasive alien species have been unintentionally spread by humans. People can carry alien species with them from one continent, country, or region to another when they travel. Shipments of goods and cargo between places can also contribute to a species’ spread.

Zebra mussels and brown marmorated stink bugs are two examples of invasive species in the US.

The recent study showed that since the year 1500, there have been 953 global extinctions. Roughly one-third of those were at least partially because of the introduction of alien species.

Oceans are absorbing a lot of the excess heat trapped on Earth because of greenhouse gases in the atmosphere. That kills marine species and coral reefs.

The planet’s oceans absorb a whopping 93% of the extra heat that greenhouse gases trap in Earth’s atmosphere. Last year was the oceans’ warmest year on record, and scientists recently realized that oceans are heating up 40% faster than they’d previously thought.

Higher ocean temperatures and acidification of the water cause corals to expel the algae living in their tissues and turn white, a process known as coral bleaching.

As a consequence, coral reefs — and the marine ecosystems they support — are dying. Around the world, about 50% of the world’s reefs have died over the past 30 years.

Species that live in fresh water are impacted by a warming planet, too.

A 2013 study showed that 82% of native freshwater fish species in California were vulnerable to extinction because of climate change.

Most native fish populations are expected decline, and some will likely be driven to extinction, the study authors said. Fish species that need water colder than 70 degrees Fahrenheit to thrive are especially at risk.

Warming oceans also lead to sea-level rise. Rising waters are already impacting vulnerable species’ habitats.

Water, like most things, expands when it heats up — so warmer water takes up more space. Already, the present-day global sea level is 5 to 8 inches higher on average than it was in 1900, according to Smithsonian.

In February, Australia’s environment minister officially declared a rodent called the Bramble Cay melomys to be the first species to go extinct because of human-driven climate change — specifically, sea-level rise.

The tiny rat relative was native to an island in the Queensland province, but its low-lying territory sat just 10 feet above sea level. The island was increasingly inundated by ocean water during high tides and storms, and those salt-water floods took a toll on the island’s plant life.

That flora provided the melomys with food and shelter, so the decrease in plants likely led to the animal’s demise.

Warming oceans are also leading to unprecedented Arctic and Antarctic ice melt, which further contributes to sea-level rise. In the US, 17% of all threatened and endangered species are at risk because of rising seas.

Melting ice sheets could raise sea levels significantly. The Antarctic ice sheet is melting nearly six times as fast as it did in the 1980s. Greenland’s ice is melting four times faster now than it was 16 years ago. It lost more than 400 billion tons of ice in 2012 alone.

In a worst-case scenario, called a “pulse,” warmer waters could cause the glaciers that hold back Antarctica’s and Greenland’s ice sheets to collapse. That would send massive quantities of ice into the oceans, potentially leading to rapid sea-level rise around the world.

Sea-level rise because of climate change threatens 233 federally protected animal and plant species in 23 coastal states across the US, according to a report from the Center for Biological Diversity.

The report noted that 17% of all the US’s threatened and endangered species are vulnerable to rising sea levels and storm surges, including the Hawaiian monk seal and the loggerhead sea turtle.

If “business as usual” continues regarding climate change, one in six species is on track to go extinct.

An analysis published in 2015 looked at over 130 studies about declining animal populations and found that one in six species could disappear as the planet continues warming.

Flora and fauna from South America and Oceania are expected top be the hardest hit by climate change, while North American species would have the lowest risk.

Previous mass extinctions came with warning signs. Those indicators were very similar to what we’re seeing now.

The most devastating mass extinction in planetary history is called the Permian-Triassic extinction, or the “Great Dying.” It happened 252 million years ago, prior to the dawn of the dinosaurs.

During the Great Dying, roughly 90% of the Earth’s species were wiped out; less than 5% of marine species survived, and only a third of land animal species made it, according to National Geographic. The event far eclipsed the cataclysm that killed the last of the dinosaurs some 187 million years later.

But the Great Dying didn’t come out of left field.

Scientists think the mass extinction was caused by a l arge-scale and rapid release of greenhouse gases into the atmosphere by Siberian volcanoes, which quickly warmed the planet — so there were warning signs. In fact, a 2018 study noted that those early signs appeared as much as 700,000 years ahead of the extinction.

“There is much evidence of severe global warming, ocean acidification, and a lack of oxygen,” the study’s lead author, Wolfgang Kießling, said in a release.

Today’s changes are similar but less severe — so far.

https://www.thisisinsider.com/signs-of-6th-mass-extinction-2019-3#previous-mass-extinctions-came-with-warning-signs-too-those-indicators-were-very-similar-to-what-were-seeing-now-14

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by David Nield

Scientists are genetically modifying mosquitoes in a high-security lab – and they’re hoping the insects will help wipe out some of the mosquito-borne diseases that continue to plague communities worldwide.

It’s known as a gene drive: where mosquitoes modified to be incapable of passing on a particular virus are used to replace the existing population of insects over several generations, with the modified genes being passed on to all their offspring.

The idea has attracted controversy because it messes with the fundamentals of nature, but it’s now under consideration by the World Health Organisation (WHO). This particular testing has entered a new phase, NPR reports, with a large-scale release of genetically modified mozzies inside a facility in Terni, Italy.

“This will really be a breakthrough experiment,” entomologist Ruth Mueller, who runs the lab, told Rob Stein at NPR. “It’s a historic moment. It’s very exciting.”

Using the ‘molecular scissor’ editing technique CRISPR, a gene known as “doublesex” in the bugs has been altered. The gene transforms female mosquitoes, taking away their biting ability and making them infertile.

At the moment, the bugs are being released in cages designed to replicate their natural environments, with hot and humid air, and places to shelter. Artificial lights are used to simulate sunrise and sunset.

The idea is to see if the mosquitoes with CRISPR-edited genetic code can wipe out the unmodified insects inside the cages. It follows on from previous proof-of-concept studies that we’ve seen before.

Ultimately these mosquitoes could be released in areas hit by malaria, bringing the local mozzie population crashing down and saving human lives. The disease is responsible for more than 400,000 deaths every year – mostly young children.

Reducing those figures sounds like a great idea, so why the controversy? Well, many scientists are urging caution when it comes to altering genetic code at this fundamental level – we just don’t know what impact these genetically edited mosquitoes will have on the world around them.

For that reason the lab has been designed to minimise any chance that the specially engineered mosquitoes could escape. The testing has also been specifically located in Italy, where this mosquito species – Anopheles gambiae – wouldn’t be able to survive outside in the natural climate.

“This is a technology where we don’t know where it’s going to end,” Nnimmo Bassey, director of the Health of Mother Earth Foundation in Nigeria, told NPR. “We need to stop this right where it is. They’re trying to use Africa as a big laboratory to test risky technologies.”

Some experts think adding genetically modified mosquitoes to natural ecosystems could harm other plants and animals that depend on them. There are a lot of unknowns.

The team behind the new experiments counters the critique by saying they’re working slowly and methodically – and that the potential side effects are outweighed by the benefits of eradicating malaria.

At the moment scientists are targeting just one species of mosquito out of hundreds, and several more years of research and consultation are planned before genetically edited mozzies would ever be released.

“There’s going to be concerns with any technology,” one of the research team, Tony Nolan from Imperial College London in the UK, told NPR.

“But I don’t think you should throw out a technology without having done your best to understand what its potential is to be transformative for medicine. And, were it to work, this would be transformative.”

https://www.sciencealert.com/scientists-take-first-step-in-controversial-mosquito-gene-drive-experiment

by ROBERT KRULWICH

Add all of us up, all 7 billion human beings on earth, and clumped together we weigh roughly 750 billion pounds. That, says Harvard biologist E.O. Wilson, is more than 100 times the biomass of any large animal that’s ever walked the Earth. And we’re still multiplying. Most demographers say we will hit 9 billion before we peak, and what happens then?

Well, we’ve waxed. So we can wane. Let’s just hope we wane gently. Because once in our history, the world-wide population of human beings skidded so sharply we were down to roughly a thousand reproductive adults. One study says we hit as low as 40.

Forty? Come on, that can’t be right. Well, the technical term is 40 “breeding pairs” (children not included). More likely there was a drastic dip and then 5,000 to 10,000 bedraggled Homo sapiens struggled together in pitiful little clumps hunting and gathering for thousands of years until, in the late Stone Age, we humans began to recover. But for a time there, says science writer Sam Kean, “We damn near went extinct.”

I’d never heard of this almost-blinking-out. That’s because I’d never heard of Toba, the “supervolcano.” It’s not a myth. While details may vary, Toba happened.

Toba, The Supervolcano

Once upon a time, says Sam, around 70,000 B.C., a volcano called Toba, on Sumatra, in Indonesia went off, blowing roughly 650 miles of vaporized rock into the air. It is the largest volcanic eruption we know of, dwarfing everything else…

That eruption dropped roughly six centimeters of ash — the layer can still be seen on land — over all of South Asia, the Indian Ocean, the Arabian and South China Sea. According to the Volcanic Explosivity Index, the Toba eruption scored an “8”, which translates to “mega-colossal” — that’s two orders of magnitude greater than the largest volcanic eruption in historic times at Mount Tambora in Indonesia, which caused the 1816 “Year Without a Summer” in the northern hemisphere.

With so much ash, dust and vapor in the air, Sam Kean says it’s a safe guess that Toba “dimmed the sun for six years, disrupted seasonal rains, choked off streams and scattered whole cubic miles of hot ash (imagine wading through a giant ashtray) across acres and acres of plants.” Berries, fruits, trees, African game became scarce; early humans, living in East Africa just across the Indian Ocean from Mount Toba, probably starved, or at least, he says, “It’s not hard to imagine the population plummeting.”

Then — and this is more a conjectural, based on arguable evidence — an already cool Earth got colder. The world was having an ice age 70,000 years ago, and all that dust hanging in the atmosphere may have bounced warming sunshine back into space. Sam Kean writes “There’s in fact evidence that the average temperature dropped 20-plus degrees in some spots,” after which the great grassy plains of Africa may have shrunk way back, keeping the small bands of humans small and hungry for hundreds, if not thousands of more years.

So we almost vanished.

But now we’re back.

It didn’t happen right away. It took almost 200,000 years to reach our first billion (that was in 1804), but now we’re on a fantastic growth spurt, to 3 billion by 1960, another billion almost every 13 years since then, till by October, 2011, we zipped past the 7 billion marker, says writer David Quammen, “like it was a “Welcome to Kansas” sign on the highway.”

In his new book Spillover, Quamman writes:

We’re unique in the history of mammals. We’re unique in this history of vertebrates. The fossil record shows that no other species of large-bodied beast — above the size of an ant, say or an Antarctic krill — has ever achieved anything like such abundance as the abundance of humans on Earth right now.
But our looming weight makes us vulnerable, vulnerable to viruses that were once isolated deep in forests and mountains, but are now bumping into humans, vulnerable to climate change, vulnerable to armies fighting over scarce resources. The lesson of Toba the Supervolcano is that there is nothing inevitable about our domination of the world. With a little bad luck, we can go too.

We once almost did.

http://www.npr.org/sections/krulwich/2012/10/22/163397584/how-human-beings-almost-vanished-from-earth-in-70-000-b-c

An animal that went extinct over 100 years ago is coming back, thanks to a group of scientists. The creature is called the quagga and while that might not sound familiar, it is a close relative of the zebra.

Just like zebras, the quagga has stripes, but for them they only appear on the front half of their bodies, and they are also brown on the rear half of their bodies. A group of scientists outside of Cape Town, Africa, called The Quagga Project, have bred an animal that looks extremely similar by using DNA and selective breeding.

In the past, the quagga roamed South Africa, but they went extinct around the 1880s after European settlers killed them at an alarming rate. However, CNN reports that after testing remaining quagga skins, which revealed the animal was a sub species of the plains zebra, the scientists hypothesized that the genes which characterized the quagga would be present in zebras and could be manifested through selective breeding.

“The progress of the project has in fact followed that prediction. And in fact we have over the course of 4, 5 generations seen a progressive reduction in striping, and lately an increase in the brown background color showing that our original idea was in fact correct,” Eric Harley, the project’s leader, told CNN.

However not everybody thinks the project was a complete success. There are several critics who believe that the project was all a stunt and that all the scientists did was create a different looking zebra.

“There are a lot of detractors who are saying you can’t possibly put back the same as what was here,” says fellow project leader Mike Gregor to CNN. Adding, “there might have been other genetic characteristics [and] adaptations that we haven’t taken into account.”

The researches say there are only six of the creatures that they now call “Rau quaggas,” (after the project’s originator Reinhold Rau) but when they have 50 of them, they then plan for the herd to live together on one reserve.

Harley tells CNN, “if we can retrieve the animals or retrieve at least the appearance of the quagga, then we can say we’ve righted a wrong.”

Scientists bring back animal that went extinct over a century ago

A multinational team of researchers has sequenced the nuclear genome of the aurochs (Bos primigenius), an extinct species of ox that inhabited Europe, Asia and North Africa.

“This is the first complete nuclear genome sequence from the extinct Eurasian aurochs,” said Dr David MacHugh of University College Dublin, Ireland, corresponding author of a paper published online in the journal Genome Biology.

Domestication of the now-extinct wild aurochs gave rise to the two major domestic extant cattle species – Bos taurus and B. indicus.

While previous genetic studies have shed some light on the evolutionary relationships between European aurochs and modern cattle, important questions remain unanswered, including the phylogenetic status of aurochs, whether gene flow from aurochs into early domestic populations occurred, and which genomic regions were subject to selection processes during and after domestication.

To build a clearer picture of the ancestry of European cattle breeds, Dr MacHugh and his colleagues from the United States, the UK, China and Ireland, extracted genetic material from a bone of a 6,750 year old wild aurochs discovered in a cave in Derbyshire, England.

The scientists then sequenced its complete genome and compared it with the genomes of 81 domesticated Bos taurus and B. indicus animals, and DNA marker information from more than 1,200 modern cows.

They discovered clear evidence of breeding between wild British aurochs and early domesticated cattle.

“Our results show the ancestors of modern British and Irish breeds share more genetic similarities with this ancient specimen than other European cattle,” Dr MacHugh said.

“This suggests that early British farmers may have restocked their domesticated herds with wild aurochs.”

“Genes linked to neurobiology and muscle development were also found to be associated with domestication of the ancestors of European cattle, indicating that a key part of the domestication process was the selection of cattle based on behavioral and meat traits.”

The study contradicts earlier simple models of cattle domestication and evolution that researchers proposed based on mitochondrial DNA or Y chromosomes.

“What now emerges from high-resolution studies of the nuclear genome is a more nuanced picture of crossbreeding and gene flow between domestic cattle and wild aurochs as early European farmers moved into new habitats such as Britain during the Neolithic,” Dr MacHugh concluded.

_____

Stephen D.E. Park et al. 2015. Genome sequencing of the extinct Eurasian wild aurochs, Bos primigenius, illuminates the phylogeography and evolution of cattle. Genome Biology 16: 234; doi: 10.1186/s13059-015-0790-2

http://www.sci-news.com/genetics/science-genome-eurasian-wild-aurochs-bos-primigenius-03377.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+BreakingScienceNews+%28Breaking+Science+News%29

One of the last five northern white rhinoceroses in the world has died.

Nabiré, a 31-year-old female northern white rhino, died of a ruptured cyst, authorities at the Dv?r Králové Zoo in the Czech Republic announced today (July 28). Nabiré’s death leaves only three females of this subspecies alive. One male, Sudan, survives on a reserve in Kenya.

Northern white rhinos (Ceratotherium simum cottoni) have been on the brink of extinction for years because of poaching and habitat loss. According to Ol Pejeta Conservancy, home to Sudan and two of the remaining female northern whites, there were only a few dozen of the animals living in the Democratic Republic of the Congo in the early 2000s. The remaining four wild survivors were last seen in 2007 and are presumed dead.

Now, the only northern whites left behind are Sudan, 42, and three females. Najin and Fatu live with Sudan in Kenya but are not capable of carrying babies — Najin because of her age and Fatu because of a uterine condition. The San Diego Zoo is home to Nola, now the only female surviving outside of Africa. She, too, is beyond reproductive age.

Nabiré was born in captivity on Nov. 15, 1983. She was plagued with uterine cysts, making it impossible for her to breed naturally. Conservationists hoped, however, that they could harvest eggs from her healthy left ovary for use in in vitro fertilization (IVF). The goal is to artificially fertilize an egg using sperm from Sudan or frozen white rhino sperm from a long-dead animal. This egg would then be transplanted into a southern white rhinoceros, the closest living relative to the rare northern whites.

But Nabiré’s condition proved fatal.

“The pathological cyst inside the body of Nabiré was huge. There was no way to treat it,” Ji?í Hrubý, a rhino curator at the zoo, said in a statement.

After Nabiré’s death, zoo researchers removed the ovary in hopes of saving some of the rhino’s now-rare genetic material.

Though more female rhinos than males survive, it’s actually eggs that are in short supply, researchers told Live Science in June. Northern white rhinos ovulate only one egg at a time every 30 days or so, which makes collecting mature eggs a slow process. Immature eggs can be harvested from the ovaries, but researchers have to develop techniques to mature those eggs in the lab.

Scientists also have to develop IVF procedures that work on rhinos, which has never been done before.

“Every species requires different culture conditions, and that’s because the actual conditions in the uterus in the animal are different,” said Barbara Durrant, director of reproductive physiology at the San Diego Zoo Institute for Conservation Research.

Durrant and her colleagues around the world are trying to make use of research on horse IVF, as horses are close relatives of rhinoceroses. But IVF is also difficult in horses, Durrant said in June.

The Dv?r Králové Zoo plans to continue its efforts to save the subspecies.

“It is our moral obligation to try to save them,” zoo director P?emysl Rabas said in a statement. “We are the only ones, perhaps with San Diego Zoo, who have enough of collected biological material to do so.”

The loss also struck Nabiré’s keepers on a personal level.

“Nabiré was the kindest rhino ever bred in our zoo,” Rabas said.

http://news.yahoo.com/northern-white-rhino-dies-leaving-only-4-left-123056144.html;_ylt=A0LEVifrd7lVKA0AHKMPxQt.;_ylu=X3oDMTEyNWZlN21nBGNvbG8DYmYxBHBvcwMxBHZ0aWQDQjA3MDBfMQRzZWMDc2M-