extinct animals

Birds Species Extinction Rates Accelerate Hundred Times Faster than Before

Spix’s macaw is now extinct in the wild. Conservation programs in Brazil maintain the last 70 or so individuals from this species.

Extinction, or the disappearance of an entire species, is commonplace. Species have been forming, persisting and then shuffling off their mortal coil since life began on Earth. However, evidence suggests the number of species going extinct, and the rate at which they disappear, is increasing dramatically.

Our recent work suggests that the rate at which species are going extinct may be many times higher than previously estimated — at least for birds. The good news, however, is that recent conservation efforts have slowed this rate a lot.

Old rates

For decades, palaeontologists have used fossils to estimate how long different species persisted before dying out. The discovery of a new fossil species gives a minimum estimate of when the species might have first evolved. The absence of the same species later in the fossil record signifies its probable extinction.

Though the methods are woefully imprecise, researchers have estimated that the average lifetime of a vertebrate species is between one and three million years. Many species are at the lower end of this range, while a few species persist many millions of years longer. For comparison, our own species, Homo sapiens, has been around for less than 500,000 years.

Such estimates can be compared to what is happening now. Conservation biologists estimate current extinction rates using historic, documented extinctions. For instance, since 1500 — just after Columbus’s arrival in the Americas — 187 of the roughly 10,000 bird species have gone extinct worldwide.

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Some simple math based on the average duration of fossil species predicts that only two to five bird species should have been lost since 1500. If the fossil data suggests a bird species will persist for three million years before going extinct, a species living in 1500 could be expected to survive for 30,000 years. In other words, a hundredfold drop.

This is the sort of calculation that supports the argument that we are approaching a “sixth mass extinction,” rivalling times in the past when extinction rates were orders of magnitude higher than the long-term average.

However, a high historical extinction rate based on data from the past few centuries may not be helpful. Using the historical extinction rate to predict current rates of extinction is similar to using car crash numbers for Model T Fords in the 1920s to predict deaths on the road in the 2020s. Many more cars hurtle down the road much faster today than they did 100 years ago. But in contrast to the 1920s, cars today sport airbags and other safety features.

Almost 80 per cent of historic bird extinctions were on oceanic islands like Hawaii, Madagascar and New Zealand, and often due to our unwitting importation of rats and snakes. Current threats include habitat destruction and climate change. And, akin to airbags, we are now much more interested in, and able to attempt, active conservation.

New rates

Using the same reasoning as before, we studied the number of species that change their status. But instead of considering extinct versus living species from long ago, we considered all levels of endangerment (the entire escalator of decline that moves species closer to extinction), and more recent data. We used numbers from the International Union for the Conservation of Nature’s Red List for all 10,000 bird species from four time points.

The Red List gives each species a threat rating based on the likelihood that it is at risk of extinction. There are six ratings in total, starting with least concern (8,714 species in 2016) and moving through critically endangered (222 species) all the way to extinct in the wild (five species).

We started with the initial records from 1988 and compared them to subsequent updates taken every four to six years. My co-authors – comparative biologist Melanie Monroe and Stuart Butchart, chief scientist at BirdLife International — tallied the number of species that remained in place, rose or descended the extinction escalator decade over decade. Using those numbers, applied mathematician Folmer Bokma calculated a current average rate of extinction — the chance an average species would go extinct in any given year.

The vast majority of species moved down the endangerment escalator. That means that they are at higher risk of extinction today than they were previously. So the final average rate of extinction was high.

Based on the Red List numbers, the expected lifespan of a species living today is only about 5,000 years — this is six times worse than the historical rate and hundreds of times worse than the average extinction rate calculated using fossils.

A silver lining?

These results are surprisingly dismal, but we also found an encouraging pattern. We calculated the overall impact of conservation activity on rates of extinction by including or excluding improvements in risk status due to conservation efforts. Without conservation, our estimate of a 5,000 year future for living species would have dropped to 3,000 years.

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Because of intense conservation efforts, a species designated as critically endangered in the past was twice as likely to improve in status as it was to become extinct in the wild. Likewise, from year to year, the probability of a critically endangered species to move up to the relative safety of merely endangered status was greater than the probability of an endangered species having its prospects become critical. This is hard evidence that conservation works.

Costs of preventing extinction

This raises an interesting challenge. It is clear that we can bring species back from the brink of extinction, and many countries engage in last-ditch efforts.

But we also know that 11th-hour intervention is expensive. For instance, in British Columbia, the government recently earmarked nearly $30 million to try to protect the few remaining caribou in the province. We have known for decades that B.C. caribou have been declining, and extreme intervention, like shooting wolves from helicopters, seems, well, desperate.

And this desperation is unnecessary. If we want to conserve particular species, we need to target them early. This means we need to pay more attention to species that are not currently critically endangered.

We must identify the species that we want to keep around and that are unlikely to deal well with the world we are creating (or maybe more accurately, destroying) for them. Importantly, these species may currently be assessed as merely vulnerable, or even of least concern. We need to get them off the extinction escalator. It bears repeating: an ounce of prevention, a stitch in time.

Arne Mooers is Professor, Biodiversity, Phylogeny and Evolution, Simon Fraser University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Study Suggests There May Be No Tigers in the Sundarbans by 2070

As the Sundarbans floods and the Bengal tigers’ habitat shrinks, the tigers could be forced to enter human settlements in the area.

New Delhi: A recent study published in the journal Science of The Total Environment has warned that climate change and the subsequent rise in sea levels could wipe out one of the largest habitats of the Bengal tigers.

The Sundarbans, an expansive mangrove forest that stretches across India and Bangladesh, is one of the last remaining tiger strongholds and home to the world’s largest population of the endangered Bengal tigers.

However, given that the Sundarbans are a low lying area – 70% of the land is just a few feet above sea level – a rising sea jeopardises the marshy land and the rich ecosystem it supports.

The study, which analyses the combined effects of climate change on the habitat of the Bengal tigers, used computer simulations to create climate scenarios developed by the Intergovernmental Panel on Climate Change for the years 2050 and 2070.

According to the New York Times, the study concluded that “by 2070, there will be no suitable tiger habitats remaining in the Bangladesh Sundarbans”.

Also read: Scientists Warn of a Looming Mass Extinction of Species

An additional factor exacerbating the Sundarban’s survival is the increasing salinity in the water – caused by reduced rainfall and rising sea levels – which will destroy the Sundri trees and thus the tigers’ mangrove habitat.

Sharif Mukul, the study’s coauthor and an assistant professor at the Independent University of Bangladesh, told CNN that in the absence of the mangroves and the Sundri trees, there will be no fresh water. And if sea levels rise, “Bengal tigers might not have any way to [survive].”

Additionally, as the Sundarbans floods and the Bengal tigers’ habitat shrinks, the tigers could be forced to enter human settlements in the area.

India is currently home to almost 70% of the world’s tiger population. Habitat loss and hunting for illegal trading of animal body parts had precipitated a sharp drop in the tiger population from an estimated 100,000 in the 1990s to fewer than 4,000.

The spike in the tiger population by 30% in India has been attributed to a decade-long effort to fight poaching and improve tiger conservation efforts.

Just last week, a sweeping UN report warned that as many as one million plant and animal species were at risk of extinction posing a serious threat to ecosystems all over the world. The rising of global temperature and sea levels has dire and cascading consequences for animal habitats, coral reefs and flood-prone areas.

IVF Posited as Last Straw to Save Nearly Extinct Northern White Rhino

Where conventional conservation methods have failed to protect a species, some believe biotechnology is the only hope.

Even before the last surviving male northern white rhino died in Ol Pejeta Conservancy, Kenya, this year, the future of the species was more or less sealed. Down to three animals in the world, all from the same family, there wasn’t much hope for a progeny.

Until now. Earlier this month, a team of scientists from Europe, Australia and Japan used in vitro fertilisation (IVF) to create the first ever rhinoceros embryo using stored white rhino semen. “With a quality of this kind, there is a 50% chance that the embryo would yield a calf that is part northern white rhino,” Cesare Galli, a cloning expert involved in the work told The Wire.

Although IVF has been used with horses, cows and humans, it has never been extended to rhinoceroses. The feat was more daunting because only two northern white rhinos remain on earth, both females. Of them, “Najin suffers from Achilles heel and cannot carry a calf while her daughter, Fatu, has a damaged uterus, ruining any chances of implantation,” said Thomas Hildebrandt, head of reproduction management at the Leibniz Institute for Zoo and Wildlife Research, Berlin.

Hildebrandt, an author of the new study, had encountered a similar situation in an earlier assignment, when he assessed the reproductive health of northern white rhinos in the San Diego Safari Park, California. Authorities were concerned that no new calves were being born. Hildebrandt’s tests showed that this was because most animals were sterile. During this exercise, researchers also collected semen samples from the bull that were frozen on site for lab analysis. A few years later, Hildebrandt assessed seven northern rhinos of the Dvůr Králové Zoo, Czech Republic. This included three bulls: Saut, Suni and Sudan.

“At that time, we didn’t expect that in about a decade we would be using these [semen samples] for creating embryos,” Hildebrandt said.

Poaching had pushed these animals to extinction in the wild, their numbers plummeting from 2,000 in the 1960s to 15 by 1984. In 2009, only seven animals were alive: five at the Dvůr Králové and two in San Diego.

To help save them, Hildebrandt decided to use assisted reproductive techniques. He approached Galli, managing director at Avantea, an Italian biotechnology and animal reproduction laboratory, and together they decided to develop ways to create implantable white rhino embryos. From its start, the project was a bumpy ride: there were limited semen samples, two surviving females both infertile and no knowledge of how exactly to proceed.

Galli had improved upon artificial insemination of horse and cattle, but to try IVF in white rhinos, they would have to study several animals and rely on trial and error. To perfect the technique, Galli and his team turned to northern white rhinos’ closest relatives, the southern white rhino. This subspecies schism is thought to have happened about a million years ago, motivated by geographical isolation (although this explanation is contested). About 20,000 southern white rhinos exist in the world, and females of the subspecies were used as a source of eggs for IVF.

Also read: Was the death of the last male northern white rhino the end of a hoax?

The first challenge was to extract the eggs from their ovaries. The ovaries are located deeper in the bodies of rhinoceroses than in horses or cattle. So Hildebrandt and his colleagues constructed a device for egg pickup. The eggs collected in this fashion are immature so Galli’s team tinkered with culture techniques to mimic internal uterine environment, allowing the eggs to mature outside the body. The final challenge was to fertilise them with sperm.

Scientists selected semen samples from both the northern and the southern white rhinos and froze them. But after thawing, they found that the sperms had lost their mobility. When they checked if the sperm would fuse with a pig egg (as is the standard procedure), only a few samples were able to manage the feat. “We had limited sample and couldn’t afford to fail,” Galli said. So instead of adding sperm to the eggs and letting nature take its course, they resorted to intra-cellular sperm injection.

But for this technique to succeed, the sperm still has to ‘activate’ the egg, and there was no guarantee that this would happen. So the team used electro-activation to tip the odds. Within an hour after sperm injection, they struck the plate holding the egg with two mild electrical jolts of 1.5 KV/cm for 30 microseconds. This jumpstarted cell division in the embryo.

Nineteen eggs fertilised with southern white rhino sperm yielded three implantable embryos. Two of the partial northern white rhino embryos (hybrid) and one pure southern white rhino embryo will be implanted in a rhinoceros after Hildebrandt and team develop a reliable implantation technique. The remaining early embryos served as a source for embryonic stem cells. These cells have the potential to form any adult rhinoceros cell. So far, scientists have found ways to differentiate them into skin cells, brain cells and mesodermal cells (the kind that lines our gut). The end game is to create a line of germ cells that would mature and yield gametes.

Another goal for the team is to use induced pluripotent stem cells to generate gametes from adult rhinoceros cells. This is important because “embryos created from closely related members will not be viable for long,” Galli explained. Semen collected from a few northern white rhinos is not enough to ensure good genetic diversity. However, scientists have also collected tissues from about 12 different northern white rhinos, and gametes produced using these are expected to be diverse enough to sustain animals born through IVF.

This is tricky and so far humans have made it work only in mice. To expand it to rhinos would require more money and more time. Thus far, the project has been keep going by the scientists themselves, and if they are to successfully “conserve white rhinos through biotechnology”, Hildebrandt said both the government and private investors would have to cough up.

Of course, there is also doubt whether this approach will work – particularly in terms of delivering the best outcomes. For example, Jo Shaw, the African rhino lead for the World Wildlife Fund (WWF), told The Wire, “Innovative assistive reproductive techniques have limited value unless there are safe places for populations to thrive.” Amit Sharma, a senior wildlife conservationist with WWF India, pitched the additional concern that the embryos developed thus far are hybrids. “There is more value in conserving species in their natural habitat,” he said.

But where conventional conservation methods have failed to protect a species, Hildebrandt believes biotechnology is the only hope. “There has been a lot of scepticism on the use of biotechnology and cloning for conservation because [conservation scientists] say it is not natural,” Galli told The Wire, adding that he hopes that their new study will help change that view.

Next, the scientists plan to perfect implantation strategies in a surrogate. They also plan to retrieve oocytes from the remaining northern white rhinos to create embryos.

While Hildebrandt thinks that the story of northern white rhinos is not yet over, there is a big problem. Even if a hundred northern white rhino calves are born in this manner, the population will still be far too low to sustain the subspecies for long. Lochran Traill, an ecologist and conservation biologist based at John Moores University, the UK, has found that the minimum viable population size for mammals is over 1,000. “But the situation for northern white rhinos is desperate,” Traill said. “I think in such a situation any desperate measure is acceptable.”

Galli agrees that the conservation efforts would have made more impact if there were more individuals. “I mean, we are not pretending to save this species through biotechnology,” he said. ‘What we are saying is that biotechnology can be an effective tool if done right.”

Sarah Iqbal is a freelance science writer.

World’s Last Remaining Wild Horses Aren’t All That ‘Wild’ After All

An examination of the genomes of dozens of ancient and modern horses concluded that Przewalski’s horse descended from horses domesticated in northern Kazakhstan some 5,500 years ago.

A herd of endangered Przewalski horses are seen at the Takhin Us National Park in the south-west part of ongolia, July 16, 2012. Credit: Reuters/Petr Josek/Files

Washington: It may come as a disappointment to equine enthusiasts, but a new genetic study has found that no truly wild horses still exist and that a population inhabiting Mongolian grasslands actually is a feral descendant of the earliest-known domesticated horses.

Przewalski’s horse, now numbering roughly 2,000 in Mongolia, was long thought to be the last wild horse – meaning no history of domestication – unlike other free-roaming horses like the mustangs of the western US that descended from steeds brought to North America centuries ago by Spaniards.

But researchers said on Thursday an examination of the genomes of dozens of ancient and modern horses concluded that Przewalski’s horse, saved from extinction in the 20th century, descended from horses domesticated in northern Kazakhstan some 5,500 years ago by people in what is called the Botai culture.

The research showed that the Botai culture offers the earliest-known evidence for horse domestication, but that their horses were not the ancestors of modern domesticated breeds.

“The world lost truly wild horses perhaps hundreds, if not thousands of years ago, but we are only just now learning this fact, with the results of this research,” said University of Kansas zoo archaeologist Sandra Olsen, one of the researchers.

The history of people and horses has been intertwined for millennia.

Przewalski’s horses graze on a meadow at the acclimatisation enclosure in the village of Dolni Dobrejov near the city of Tabor, Czech Republic, June 18, 2017. Credit: Reuters/David W. Cerny/Files

“Horse domestication was a critical innovation,” said archaeologist Alan Outram of the University of Exeter in England, who helped lead the study.

“Horse riding was the fastest form of transport for thousands of years, from the Copper Age over 5,000 years ago until the steam train. Even then it was really only the motor car that replaced it on a wide scale. Horses revolutionised human mobility, trade and modes of warfare,” Outram added.

Przewalski’s horse, named for a Russian who described them in the 19th century, is relatively small and stocky. Like horses depicted in prehistoric cave paintings, it is dun-colored with a dark erect mane. The current population is descended from 15 individuals caught a century ago, with Przewalski’s horse later reintroduced into the wild.

Some horses from the domesticated Botai herds escaped and became the feral Przewalski’s horse, the researchers said.

“This means that we must continue the search for the true ancestors of modern breeds by gathering samples from places like Ukraine, western Russia, Hungary, Poland and that region,” Olsen added.

The research was published in the journal Science.

(Reuters)