Sequencing the DNA in a scoop of dirt can tell scientists what creatures are living nearby, a new study using soil from safari parks shows, and the amount of DNA present can even tell how many individuals of each species there are, which could allow field biologists to get preliminary surveys of species. But though the team managed to identify nearly all the species they had expected in the parks, from wildebeest to elephants, they are still addressing how to take samples that accurately represent the area’s biodiversity—one would have to avoid elephant latrines or wildebeest sleeping areas, for instance—and there is the additional problem that rare or small creatures, like insects, might easily be missed. That said, it’s still an unusual and interesting way to take a look at an area’s inhabitants without actually tracking them down.
Read more at Scientific American.
Image courtesy of malcyzk / flickr
It’s no secret that an alarming number of species around the world, especially vertebrates, are in trouble. But is the notion that the Earth is on the brink of a sixth major extinction event—the first since the dinosaur die-off—true, or alarmist? In Nature this week, a team of scientists sought to answer the question directly by counting as many species (and extinctions) as they could in the fossil record and the recent historical record. The result is gloomy news: There’s still a chance to avert much of the crisis, but if nothing changes, such a mass extinction event really could happen in the span of just a few centuries.
Mass extinctions include events in which 75 percent of the species on Earth disappear within a geologically short time period, usually on the order of a few hundred thousand to a couple million years. It’s happened only five times before in the past 540 million years of multicellular life on Earth. (The last great extinction occurred 65 million years ago, when the dinosaurs were wiped out.) At current rates of extinction, the study found, Earth will enter its sixth mass extinction within the next 300 to 2,000 years. [MSNBC]
That range of time the researchers give is so large because of the great diversity of life—it makes it hard to track exactly how many species are disappearing, and how quickly. (Indeed, DISCOVER has covered how biologists are discovering many new species these days just as those species face extinction). So Anthony Barnosky and his team made conservative estimates based on the available evidence. For instance, they pegged the rate of mammal extinction at 80 species out of a total of 5,000-plus in the last five centuries. That may not sound like much, but when you consider the speed at which things typically happen on a geologic scale, it is a faster rate of species loss than the previous five mass extinctions saw, scientists believe.
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The buzzwords of the week in Moscow are tiger and conservation.
Sunday marked the opening of the worldwide tiger summit, which brought together high-level representatives from the 13 tiger-habitat countries, including Russia and China, to discuss the best plan to save the tigers. The meeting goes through Wednesday.
Only about 3,200 tigers remain in the wild, and without help experts say populations will start to go extinct in less than 20 years.
“Here’s a species that’s literally on the brink of extinction,” said Jim Leape, director general of conservation group WWF. “This is the first time that world leaders have come together to focus on saving a single species, and this is a unique opportunity to mobilise the political will that’s required in saving the tiger.” [BBC News]
The working plan includes provisions to decrease poaching and smuggling of the tigers and calls for more protected habitats. Researchers say that if tigers are left alone and provided with enough habitat and prey, the population could double in 12 years.
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What does it take to make a wellspring of biodiversity like the Amazon rainforest? A huge mountain range, a blast of heat, and a little time.
A pair of studies in this week’s edition of Science attempt to sort through tropical natural history and reach the root causes of Amazonia’s embarrassment of biological riches. The first, led by palaeoecologist Carina Hoorn, points to the influence of the Andes Mountains, the spine of South America that runs up its western coast. Sometime between about 35 and 65 million years ago, colliding tectonic plates sent the Andes bulging up. According to the researchers, the birth of a mountain range set of an ecological chain reaction.
The rising mountains that resulted from the uplift blocked humid air from the Atlantic, eventually increasing rainfall along the eastern flank of what became the Andes that eroded nutrient-loaded soils off the mountains. The Andes also kept water from draining into the Pacific, helping form vast wetlands about 23 million years ago that were home to a wide range of mollusks and reptiles. [LiveScience]
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While the temperature effects of climate change are expected to be less dramatic in the equatorial regions, the cold-blooded tropical animals that live there may be in for a dramatic shock.
A study published this week in Nature focused on these cold-blooded animals–including insects, amphibians, and lizards–whose body temperatures are not constant, but instead rise and fall with the temperature of their environment. The researchers found that these creatures show great increases in their metabolism from slight changes in temperature; the metabolic increases were on the order of twice that of warm-blooded animals.
“The assumption has been that effects on organisms will be biggest in the place where the temperature has changed the most,” [first author Michael] Dillon said. “The underlying assumption is that … no matter where you start, a change means the same thing. But with physiology, that’s rarely the case.” [Scientific American].
This means that though climate change will be more extreme in toward the Earth’s poles, the cold-blooded animals that live near the equator (where changes should be milder) may react more strongly to the changes.
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Earlier this week we brought you news of water woes in the American southwest, where reservoir levels have dropped dangerously low, and in China, where the government is spending $60 billion to route water to parched cites like Beijing. Now comes news of just how widespread the world’s water problems really are. A study in Nature reports that nearly 80 percent of the world’s population lives in areas where the fresh water supply isn’t secure. And while industrialized nations have made massive investments in infrastructure to keep the faucets flowing, those projects have taken a toll on the environment.
[The researchers] say that in western countries, conserving water for people through reservoirs and dams works for people, but not nature. They urge developing countries not to follow the same path. Instead, they say governments should to invest in water management strategies that combine infrastructure with “natural” options such as safeguarding watersheds, wetlands and flood plains. [BBC News]
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Images: Nature / C. J. Vörösmarty et al.
Two weeks ago we covered the dust-up between eco-groups and the government of Tanzania over the latter’s proposal to build a road through the heart of Serengeti National Park, home to the world-famous annual migrations of wildebeests, zebras, and more. Today in Nature, a group of 27 scientists chimed in on the project. Their verdict: It would be a biodiversity disaster.
Conservationists led by Princeton’s Andrew Dobson … argue the planned 2012 road would stop the yearly migration of 1.3 million wildebeests, the cornerstone species of the park, and harm other animals such as the 1.5 million zebras that yearly migrate as well. [USA Today]
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Sponges are just about the simplest animals on the Earth. And they might be the oldest ones we know, too.
Adam Maloof and colleagues published a study in Nature Geoscience this week about their find that could push back the oldest known animal life by 70 million years. In Australia, Maloof says, the team found remains of ancient sponges dating to about 650 million years ago.
The prior oldest known hard-bodied animals were reef-dwelling organisms called Namacalathus, which date to approximately 550 million years ago. Disputed remains for other possible soft-bodied animals date to between 577 and 542 million years ago [Discovery News].
At 650 million years old, the sponges would predate the Cambrian Explosion—a huge blossoming of diversity in animal life—by 100 million years. These organisms would also predate an intense moment in our planet’s history known as “Snowball Earth,” according to paleobiologist Martin Brasier. It’s even possible that they helped cause it.
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The Pavlovsk Experimental Station, near St. Petersburg, Russia, was founded in the 1920s. About 90 percent of the plants grown there occur nowhere else, making the collection an island of agricultural biodiversity. And the station soon may be knocked over to make way for a housing development.
The station’s operators at the Vavilov Institute of Plant Industry lost a court ruling this week, so the land upon which all those plants sit will be given to the Russian Housing Development Foundation. The plant scientists bought themselves an extra month with an instant appeal, but the situation looks grim.
“We expected to lose,” agrees Cary Fowler, executive director of the Global Crop Diversity Trust in Rome, who has spent months campaigning against the station’s destruction. “Our real hope lies with President Medvedev and Prime Minister Putin, who could both override the decision of the courts. At least the higher appeal will give us time to mobilize more people and hopefully get through the gates of the Kremlin,” he adds [Nature].
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A flying frog that changes colors, a stick insect that’s a foot and a half long, and a “ninja slug” that shoots “love darts.” These are among the 120 new species discovered or described over the past three years on the lush island of Borneo–the Southeast Asia island divided between Malaysia, Indonesia, and Brunei.
On Earth Day, the conservation group WWF released a report on some of the recent discoveries in a 54-million-acre nature preserve known as the Heart of Borneo. WWF ecologist Adam Tomasek says that on an average, three new species were found every month.
Teenage Mutant Ninja Slugs?
This colorful green and yellow slug species, named Ibycus rachelae, was discovered atop high mountains in the Malaysian section of Borneo. The slug has a tail three times the length of its head, and it wraps the tail around itself when it is resting. From the Ariophantidae family, this unusual species makes use of so-called ‘love darts’ in courtship. Made of calcium carbonate, the love dart is harpoon-like which pierces and injects a hormone into a mate, and may play a role in increasing the chances of reproduction [Guardian].
Image: Peter Koomen / WWF
Kaleidoscopic. Delightfully odd. And too numerous to truly grasp.
There are many more words one could deploy to describe the worlds unknown under the sea. An international group of scientists has been scouring them for life for the last decade, and later this year, on October 4, the Census of Marine Life will release it catalog of marine inhabitants. “The number could be astonishingly large, perhaps a million or more, if all small animals and protists are included,” the organization says.
Octopuses, jellyfish, and other sprawling sea creatures dominated the census’ prior reports. But this time they’ve dived even deeper, surveying tiny life. Remotely operated deep-sea vehicles discovered that roundworms dominate the deepest, darkest abyss. Sometimes, more than 500,000 can exist in just over a square yard of soft clay [AP].
And then there are the microbes. The scientists conservatively estimate that there must be at least 20 million kinds of microbe in the oceans. The true number may even be billions or trillions [Nature]. Individual microbes reach even more astronomical number. There are probably a nonillion of them in the sea, the scientists estimate. That’s a billion cubed, and then times 1,000. Or, if you prefer your measurements given in the weight of African elephants, it’d be 240 billion of them.
Take a peek through this quick slideshow of some of the weirdest ocean life seen so far.
Image: David Patterson et. al.
The people who lived in the Amazon regions back before any Europeans showed up on the scene had an ingenious way to survive there. By creating mounds of biochar, the pre-Columbian peoples made beds for their crops that drained far better than the native soil, which is nutrient-poor and prone to flooding. And, it seems, they unintentionally contributed to the biodiversity of the region.
In a study in the Proceedings of the National Academy of Sciences, scientists led by Doyle McKey of France investigated the savannas of French Guiana, in the far northern part of South America. These plains are flooded during the rainy season, dry and parched in the summer, and often burned by fires. It was while walking through this landscape that McKey started wondering about undulations in the terrain [New Scientist]. Just how effective were these people at creating favorable cropland? McKey found that the drainage capacity of the mounds was nine times that of the rest of the savanna.
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The human genome may have been sequenced back in 2004, but that was a far cry from documenting all the genes inside us. Our bodies are home to a dizzying number and variety of bacteria, and in a study published in this week’s Nature, researchers have used metagenomic sequencing to catalog the genes that belong to the microbes living in our guts.
The project, which sampled 124 European people, found that each individual had at least 160 species of bacteria living in his or her digestive tract, and there’s a lot of overlap between our guts. At least 57 species of bacteria were present in just about everybody. Overall, the researchers cataloged about 1,000 different bacteria species and figure there’s another 150 or so they haven’t found [AP].
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Brazil’s controversial plan to build the third-largest dam in the world right in Amazon rainforest got the go-ahead from the environmental ministry this week. The ministers approved the permits for the dam project, and now companies can begin to bid on the building rights. But whoever wins will have to pay out at least some money to protect the local environment.
The 11,000-megawatt Belo Monte dam is part of Brazil’s largest concerted development plan for the Amazon since the country’s military government cut highways through the rainforest to settle the vast region during its two-decade reign starting in 1964 [Reuters]. Nearly all huge dam projects raise environmental concerns because they flood vast areas and can change ecosystems so drastically. But the Belo Monte, to be built on the Xingu River, has the additional trouble of being in one of the most important habitats in world and near to populations of indigenous peoples. The Xingu is a tributary of the Amazon River.
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In an ambitious attempt to assess how humans are doing as stewards of planet earth, 28 leading scientists have drawn up a list of nine “planetary boundaries” that must not be crossed if we want to avoid drastically changing the global environment and imperiling our own existence. The only problem is, we’ve already crossed three of those thresholds.
The paper, published in Nature (and available for free), aims to define a “safe operating space” for human life on the planet. It’s a first-draft users’ manual for an era that scientists dub the “anthropocene,” in which nearly seven billion resource-hungry humans have come to dominate ecological change on Earth [Wired.com]. What follows is a list of the nine environmental factors, and how we’re doing on living within each limit.
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