A giant insect ecosystem is collapsing due to humans. It’s a catastrophe

Michael McCarthy writes: Thirty-five years ago an American biologist Terry Erwin conducted an experiment to count insect species. Using an insecticide “fog”, he managed to extract all the small living things in the canopies of 19 individuals of one species of tropical tree, Luehea seemannii, in the rainforest of Panama. He recorded about 1,200 separate species, nearly all of them coleoptera (beetles) and many new to science; and he estimated that 163 of these would be found on Luehea seemannii only.

He calculated that as there are about 50,000 species of tropical tree, if that figure of 163 was typical for all the other trees, there would be more than eight million species, just of beetles, in the tropical rainforest canopy; and as beetles make up about 40% of all the arthropods, the grouping that contains the insects and the other creepy-crawlies from spiders to millipedes, the total number of such species in the canopy might be 20 million; and as he estimated the canopy fauna to be separate from, and twice as rich as, the forest floor, for the tropical forest as a whole the number of species might be 30 million.

Yes, 30 million. It was one of those extraordinary calculations, like Edwin Hubble’s of the true size of the universe, which sometimes stop us in our tracks.

Erwin reported that he was shocked by his conclusions and entomologists have argued over them ever since. But about insects, his findings make two things indisputably clear. One is that there are many, many more types than the million or so hitherto described by science, and probably many more than the 10m species sometimes postulated as an uppermost figure; and the second is that this is far and away the most successful group of creatures the Earth has ever seen.

They are multitudinous almost beyond our imagining. They thrive in soil, water, and air; they have triumphed for hundreds of millions of years in every continent bar Antarctica, in every habitat but the ocean. And it is their success – staggering, unparalleled and seemingly endless – which makes all the more alarming the great truth now dawning upon us: insects as a group are in terrible trouble and the remorselessly expanding human enterprise has become too much, even for them.

Does it matter? Oh yes. Most of our fruit crops are insect-pollinated, as are the vast majority of our wild plants
The astonishing report highlighted in the Guardian, that the biomass of flying insects in Germany has dropped by three quarters since 1989, threatening an “ecological Armageddon”, is the starkest warning yet; but it is only the latest in a series of studies which in the last five years have finally brought to public attention the real scale of the problem. [Continue reading…]

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Introducing ‘dark DNA’ – the phenomenon that could change how we think about evolution

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By Adam Hargreaves, University of Oxford

DNA sequencing technology is helping scientists unravel questions that humans have been asking about animals for centuries. By mapping out animal genomes, we now have a better idea of how the giraffe got its huge neck and why snakes are so long. Genome sequencing allows us to compare and contrast the DNA of different animals and work out how they evolved in their own unique ways.

But in some cases we’re faced with a mystery. Some animal genomes seem to be missing certain genes, ones that appear in other similar species and must be present to keep the animals alive. These apparently missing genes have been dubbed “dark DNA”. And its existence could change the way we think about evolution.

My colleagues and I first encountered this phenomenon when sequencing the genome of the sand rat (Psammomys obesus), a species of gerbil that lives in deserts. In particular we wanted to study the gerbil’s genes related to the production of insulin, to understand why this animal is particularly susceptible to type 2 diabetes.

But when we looked for a gene called Pdx1 that controls the secretion of insulin, we found it was missing, as were 87 other genes surrounding it. Some of these missing genes, including Pdx1, are essential and without them an animal cannot survive. So where are they?

The first clue was that, in several of the sand rat’s body tissues, we found the chemical products that the instructions from the “missing” genes would create. This would only be possible if the genes were present somewhere in the genome, indicating that they weren’t really missing but just hidden.

[Read more…]

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Beating the odds for lucky mutations

Jordana Cepelewicz writes: In 1944, a Columbia University doctoral student in genetics named Evelyn Witkin made a fortuitous mistake. During her first experiment in a laboratory at Cold Spring Harbor, in New York, she accidentally irradiated millions of E. coli with a lethal dose of ultraviolet light. When she returned the following day to check on the samples, they were all dead — except for one, in which four bacterial cells had survived and continued to grow. Somehow, those cells were resistant to UV radiation. To Witkin, it seemed like a remarkably lucky coincidence that any cells in the culture had emerged with precisely the mutation they needed to survive — so much so that she questioned whether it was a coincidence at all.

For the next two decades, Witkin sought to understand how and why these mutants had emerged. Her research led her to what is now known as the SOS response, a DNA repair mechanism that bacteria employ when their genomes are damaged, during which dozens of genes become active and the rate of mutation goes up. Those extra mutations are more often detrimental than beneficial, but they enable adaptations, such as the development of resistance to UV or antibiotics.

The question that has tormented some evolutionary biologists ever since is whether nature favored this arrangement. Is the upsurge in mutations merely a secondary consequence of a repair process inherently prone to error? Or, as some researchers claim, is the increase in the mutation rate itself an evolved adaptation, one that helps bacteria evolve advantageous traits more quickly in stressful environments?

The scientific challenge has not just been to demonstrate convincingly that harsh environments cause nonrandom mutations. It has also been to find a plausible mechanism consistent with the rest of molecular biology that could make lucky mutations more likely. Waves of studies in bacteria and more complex organisms have sought those answers for decades. [Continue reading…]

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Here’s what the last common ancestor of apes and humans looked like

Charles Q. Choi writes: The most complete extinct-ape skull ever found reveals what the last common ancestor of all living apes and humans might have looked like, according to a new study.

The 13-million-year-old infant skull, which its discoverers nicknamed “Alesi,” was unearthed in Kenya in 2014. It likely belonged to a fruit-eating, slow-climbing primate that resembled a baby gibbon, the researchers said.

Among the living primates, humans are most closely related to the apes, which include the lesser apes (gibbons) and the great apes (chimpanzees, gorillas and orangutans). These so-called hominoids — that is, the gibbons, great apes and humans — emerged and diversified during the Miocene epoch, approximately 23 million to 5 million years ago. (The last common ancestor that humans had with chimpanzees lived about 6 million to 7 million years ago.)

Much remains unknown about the common ancestors of living apes and humans from the critical time when these branches diverged. Fossil evidence from this part of the primate family tree is scarce, and consists mostly of isolated teeth and broken jaw fragments. As such, researchers were not sure what the last common ancestors of living apes and humans might have looked like, and even whether they originated in Africa or Eurasia. [Continue reading…]

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How to slam dunk creationists when it comes to the theory of evolution

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By Paul Braterman, University of Glasgow

The 2001 discovery of the seven million-year-old Sahelanthropus, the first known upright ape-like creatures, was yet more proof of humanity’s place among the great apes. And yet Mike Pence, then a representative and now US vice president, argues for the opposite conclusion.

For him, our ideas about our ancestors have changed, proving once more that evolution was a theory, and therefore we should be free to teach other theories alongside evolution in our classrooms.

A skull cast of Sahelanthropus, the first upright ape-like creatures which lived seven million years ago.
Didier Descouens, CC BY-SA

How to respond? The usual answer is that we should teach students the meaning of the word “theory” as used in science – that is, a hypothesis (or idea) that has stood up to repeated testing. Pence’s argument will then be exposed to be what philosophers call an equivocation – an argument that only seems to make sense because the same word is being used in two different senses.

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Octopus research shows that consciousness isn’t what makes humans special

Olivia Goldhill writes: Whether or not octopuses should be viewed as charming or terrifying very much depends on your personal perspective. But it’s hard to deny their intelligence.

Octopuses can squirt water at an annoyingly bright bulb until it short-circuits. They can tell humans apart (even those who are wearing the same uniform). And, according to Peter Godfrey-Smith, a philosophy professor at University of Sydney and City University of New York, they are the closest creature to an alien here on earth.

That’s because octopuses are the most complex animal with the most distant common ancestor to humans. There’s some uncertainty about which precise ancestor was most recently shared by octopuses and humans, but, Godfrey-Smith says, “It was probably an animal about the size of a leech or flatworm with neurons numbering perhaps in the thousands, but not more than that.”

This means that octopuses have very little in common with humans, evolution-wise. They have developed eyes, limbs, and brains via a completely separate route, with very different ancestors, from humans. And they seem to have come by their impressive cognitive functioning—and likely consciousness—by different means. [Continue reading…]

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Aliens in our midst

Douglas Fox writes: Leonid Moroz has spent two decades trying to wrap his head around a mind-boggling idea: even as scientists start to look for alien life in other planets, there might already be aliens, with surprisingly different biology and brains, right here on Earth. Those aliens have hidden in plain sight for millennia. They have plenty to teach us about the nature of evolution, and what to expect when we finally discover life on other worlds.

Moroz, a neuroscientist, saw the first hint of his discovery back in the summer of 1995, not long after arriving in the United States from his native Russia. He spent that summer at the Friday Harbor marine laboratory in Washington. The lab sat amid an archipelago of forested islands in Puget Sound – a crossroads of opposing tides and currents that carried hundreds of animal species past the rocky shore: swarms of jellyfish, amphipod crustaceans, undulating sea lilies, nudibranch slugs, flatworms, and the larvae of fish, sea stars and countless other animals. These creatures represented not just the far reaches of Puget Sound, but also the farthest branches of the animal tree of life. Moroz spent hours out on the pier behind the lab, collecting animals so he could study their nerves. He had devoted years to studying nervous systems across the animal kingdom, in hopes of understanding the evolutionary origin of brains and intelligence. But he came to Friday Harbor to find one animal in particular.

He trained his eyes to recognise its bulbous, transparent body in the sunlit water: an iridescent glint and fleeting shards of rainbow light, scattered by the rhythmic beating of thousands of hair-like cilia, propelling it through the water. This type of animal, called a ctenophore (pronounced ‘ten-o-for’ or ‘teen-o-for’), was long considered just another kind of jellyfish. But that summer at Friday Harbor, Moroz made a startling discovery: beneath this animal’s humdrum exterior was a monumental case of mistaken identity. From his very first experiments, he could see that these animals were unrelated to jellyfish. In fact, they were profoundly different from any other animal on Earth.

Moroz reached this conclusion by testing the nerve cells of ctenophores for the neurotransmitters serotonin, dopamine and nitric oxide, chemical messengers considered the universal neural language of all animals. But try as he might, he could not find these molecules. The implications were profound.

The ctenophore was already known for having a relatively advanced nervous system; but these first experiments by Moroz showed that its nerves were constructed from a different set of molecular building blocks – different from any other animal – using ‘a different chemical language’, says Moroz: these animals are ‘aliens of the sea’.

If Moroz is right, then the ctenophore represents an evolutionary experiment of stunning proportions, one that has been running for more than half a billion years. This separate pathway of evolution – a sort of Evolution 2.0 – has invented neurons, muscles and other specialised tissues, independently from the rest of the animal kingdom, using different starting materials. [Continue reading…]

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How to turn a fox into a dog

Lee Dugatkin and Lyudmila Trut: Deep inside my soul,” says Lyudmila Trut, “is a pathological love for animals.” She inherited this from her mother, who was a great dog lover. Lyudmila had grown up with dogs as pets, and even during World War II, when food was horribly scarce, her mother would feed starving stray dogs, telling her, “If we don’t feed them, Lyudmila, how will they survive? They need people.” Following her mother’s example, Lyudmila always carries some kind of treat in a pocket in case she encounters a stray dog. And she’s never forgotten that domesticated animals need people. She knows that this is how we’ve designed them.

In 1958, Lyudmila was just finishing up her studies at Moscow State University, home of Leonid Krushinsky, a pioneering Russian researcher in animal behavior. Dmitri Belyaev was friends with Krushinsky and admired his work. Belyaev had recently accepted a position as vice director of a new research institute in a giant Soviet city of science called Akademgorodok, near Novosibirsk, Siberia. He was searching for someone to lead an experiment he would begin in earnest at Akademgorodok. Dmitri intended to run an experiment domesticating silver foxes, and so the person he sought needed the kind of sophisticated skills in animal behavior that Krushinksy taught.

Belyaev went to visit Krushinsky at his office at Moscow State’s Sparrow Hill campus for advice about who might work with him on this experiment. Ensconced in the grand setting of Krushinsky’s building, with its palatial ceilings, marble floors, ornate columns, and fine art statues, he described his plans for the experiment and explained that he was looking for talented graduates to assist with the work. Krushinsky put the word out, and when Lyudmila heard about the opportunity, she was immediately captivated. Her own undergraduate work had been on the behavior of crabs, and as fascinating as their complex behavior could be, the prospect of working with foxes, so closely related to her beloved dogs, and with such a well-respected scientist as Belyaev, was tantalizing.

In early 1958, Lyudmila went to meet with Belyaev at his office. She was immediately struck by how unusual he was for a male Soviet scientist, especially one of his rank. Many were quite high-handed, and condescending to women. Lyudmila, who has a genial, smiling manner and stands just five feet tall, with her wavy brown hair cropped quite short, looked young for her age, and she hadn’t even finished her undergraduate studies, but Dmitri spoke to her as an equal. She was riveted, she recalls, by his piercing blue eyes, which so strongly communicated his intelligence and drive, but also emanated an extraordinary empathy.

She felt privileged to be invited into the confidence of this extraordinary man, who shared with her so openly about the bold work he was proposing. She had never experienced such a distinctive combination of confidence and warmth in a person. Dmitri told Lyudmila what he had in mind. “He told me that he wanted to make a dog out of a fox,” she recalls. Probing how creative she would be about conducting the experiment, Belyaev asked her, “You are now located on a fox farm that has several hundred foxes, and you need to select the 20 calmest ones for the experiment. How will you do it?” She had no experience whatsoever with foxes, and had only a vague notion of what the fox farms might be like and what sort of welcome she might receive at them. But she was a confident young woman, and she did the best she could to suggest some reasonable possibilities. She would try different methods, she said, talk to people who had worked with foxes, read up on what was known in the literature. Dmitri sat back and listened, gauging how committed she would be to the work and to developing techniques for such a novel study. She must be not only rigorously scientific, but also quite inventive. Was she really ready to go to Novosibirsk, to move to Akademgorodok, he asked her? After all, moving to the heart of Siberia was a life change not to be taken lightly. [Continue reading…]

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In Neanderthal DNA, signs of a mysterious human migration

Carl Zimmer writes: With fossils and DNA, scientists are piecing together a picture of humanity’s beginnings, an origin story with more twists than anything you would find at the movie theater.

The expert consensus now is that Homo sapiens evolved at least 300,000 years ago in Africa. Only much later — roughly 70,000 years ago — did a small group of Africans establish themselves on other continents, giving rise to other populations of people today.

To Johannes Krause, the director of the Max Planck Institute for Human History in Germany, that gap seems peculiar. “Why did people not leave Africa before?” he asked in an interview. After all, he observed, the continent is physically linked to the Near East. “You could have just walked out.”

In a study published Tuesday in Nature Communications, Dr. Krause and his colleagues report that Africans did indeed walk out — over 270,000 years ago.

Based on newly discovered DNA in fossils, the researchers conclude that a wave of early Homo sapiens, or close relatives of our species, made their way from Africa to Europe. There, they interbred with Neanderthals.

Then the ancient African migrants disappeared. But some of their DNA endured in later generations of Neanderthals.

“This is now a comprehensive picture,” Dr. Krause said. “It brings everything together.” [Continue reading…]

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Can microbes encourage altruism?

Elizabeth Svoboda writes: Parasites are among nature’s most skillful manipulators — and one of their specialties is making hosts perform reckless acts of irrational self-harm. There’s Toxoplasma gondii, which drives mice to seek out cats eager to eat them, and the liver fluke Dicrocoelium dendriticum, which motivates ants to climb blades of grass, exposing them to cows and sheep hungry for a snack. There’s Spinochordodes tellinii, the hairworm that compels crickets to drown themselves so the worm can access the water it needs to breed. The hosts’ self-sacrifice gains them nothing but serves the parasites’ hidden agenda, enabling them to complete their own life cycle.

Now researchers are beginning to explore whether parasitic manipulations may spur host behaviors that are selfless rather than suicidal. They are wondering whether microbes might be fundamentally responsible for many of the altruistic behaviors that animals show toward their own kind. Altruism may seem easy to justify ethically or strategically, but explaining how it could have persisted in a survival-of-the-fittest world is surprisingly difficult and has puzzled evolutionary theorists going all the way back to Darwin. If microbes in the gut or other tissues can nudge their hosts toward generosity for selfish reasons of their own, altruism may become less enigmatic.

A recently developed mathematical model and related computer simulations by a trio of researchers at Tel Aviv University appear to validate this theory. The researchers showed that transmissible microbes that promoted altruism in their hosts won the survival battle over microbes that did not — and when this happened, altruism became a stable trait in the host population. The research was published in Nature Communications earlier this year.

“The story is fascinating, because we don’t think of altruism in terms of the host-microbiome relationship,” said John Bienenstock, a biologist at McMaster University in Hamilton, Ontario, and director of the Brain-Body Institute at St. Joseph’s Healthcare Hamilton, who was not involved with the simulation work. “You can’t ignore the possible effect of what your bug population is doing.” [Continue reading…]

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Was the first song a lullaby?

Tom Jacobs writes: Why do humans play, and listen, to music? The question has long baffled evolutionary theorists. Some suggest it had its origins in courtship rituals, while others contend it had (and has) a unique ability to bond people together to work toward a common goal.

Now, a couple of Harvard University researchers have proposed a new concept: They argue that the earliest music  —  and perhaps the prototype for everything from Bach to rap  — may just have been the songs mothers sing to their infants.

Maybe the first musical genre wasn’t the love song, but rather the lullaby.

“The evolution of music must be a complex, multi-step process, with different features developing for different reasons,” says Samuel Mehr, who co-authored the paper with psychologist Max Krasnow. “Our theory raises the possibility that infant-directed song is the starting point for all that.”

Mothers vocalize to their babies “across many, if not all, cultures,” the researches note in the journal Evolution and Human Behavior. Its ubiquity suggests this activity plays a positive role in the parent-child relationship, presumably soothing infants by proving that someone is there and paying attention to them. [Continue reading…]

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New evidence that Lucy, our most famous ancestor, had superstrong arms

The Washington Post reports: In Ethiopia, she is known as “Dinkinesh” — Amharic for “you are marvelous.” It’s an apt name for one of the most complete ancient hominid skeletons ever found, an assemblage of fossilized bones that has given scientists unprecedented insight into the history of humanity.

You probably know her as Lucy.

Discovered in 1974, wedged into a gully in Ethiopia’s Awash Valley, the delicate, diminutive skeleton is both uncannily familiar and alluringly strange. In some ways, the 3.2-million-year-old Australopithecus was a lot like us; her hips, feet and long legs were clearly made for walking. But she also had long arms and dexterous curved fingers, much like modern apes that still swing from the trees.

So, for decades scientists have wondered: Who exactly was Lucy? Was she lumbering and land-bound, like us modern humans? Or did she retain some of the ancient climbing abilities that made her ancestors — and our own — champions of the treetops?

A new study suggests she was a little of both: Though her lower limbs were adapted for bipedalism, she had exceptionally strong arm bones that allowed her to haul herself up branches, researchers reported Wednesday in the journal PLoS One. [Continue reading…]

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Dino-killing asteroid may have punctured Earth’s crust

Live Science reports: After analyzing the crater from the cosmic impact that ended the age of dinosaurs, scientists now say the object that smacked into the planet may have punched nearly all the way through Earth’s crust, according to a new study.

The finding could shed light on how impacts can reshape the faces of planets and how such collisions can generate new habitats for life, the researchers said.

Asteroids and comets occasionally pelt Earth’s surface. Still, for the most part, changes to the planet’s surface result largely from erosion due to rain and wind, “as well as plate tectonics, which generates mountains and ocean trenches,” said study co-author Sean Gulick, a marine geophysicist at the University of Texas at Austin.

In contrast, on the solar system’s other rocky planets, erosion and plate tectonics typically have little, if any, influence on the planetary surfaces. “The key driver of surface changes on those planets is constantly getting hit by stuff from space,” Gulick told Live Science. [Continue reading…]

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Huddled mice could change the way we think about evolution

Stuart P Wilson, University of Sheffield and James V Stone, University of Sheffield

Adapt or die. That’s the reality for an animal species when it is faced with a harsh environment. Until now, many scientists have assumed that the more challenging an animal’s environment, the greater the pressure to adapt and the faster its genes evolve. But we have just published new research in Royal Society Open Science that shows that genes might actually evolve faster when the pressure to adapt is reduced.

We built a simple computer model of how evolution may be affected by the way animals interact with each other when they’re in groups. Specifically, we looked at what happens to animals that huddle together to keep warm.

We found that when animals huddle in larger groups, their genes for regulating temperature evolve faster, even though there is less pressure to adapt to the cold environment because of the warmth of the huddle. This shows that an organism’s evolution doesn’t just depend on its environment but also on how it behaves.

When animals such as rats and mice huddle together in groups, they can maintain a high body temperature without using as much energy as they would on their own. We wanted to understand how this kind of group behaviour would affect a species’ evolution.

To do this, we built a computer model simulating how the species’ genes changed and were passed on over multiple generations. When the effects of huddling were built into the computer model, the reduced pressure to adapt was actually found to accelerate evolution of the genes controlling heat production and heat loss.

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A unified theory of evolution requires input from Darwin and Lamarck

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Michael Skinner writes: The unifying theme for much of modern biology is based on Charles Darwin’s theory of evolution, the process of natural selection by which nature selects the fittest, best-adapted organisms to reproduce, multiply and survive. The process is also called adaptation, and traits most likely to help an individual survive are considered adaptive. As organisms change and new variants thrive, species emerge and evolve. In the 1850s, when Darwin described this engine of natural selection, the underlying molecular mechanisms were unknown. But over the past century, advances in genetics and molecular biology have outlined a modern, neo-Darwinian theory of how evolution works: DNA sequences randomly mutate, and organisms with the specific sequences best adapted to the environment multiply and prevail. Those are the species that dominate a niche, until the environment changes and the engine of evolution fires up again.

But this explanation for evolution turns out to be incomplete, suggesting that other molecular mechanisms also play a role in how species evolve. One problem with Darwin’s theory is that, while species do evolve more adaptive traits (called phenotypes by biologists), the rate of random DNA sequence mutation turns out to be too slow to explain many of the changes observed. Scientists, well-aware of the issue, have proposed a variety of genetic mechanisms to compensate: genetic drift, in which small groups of individuals undergo dramatic genetic change; or epistasis, in which one set of genes suppress another, to name just two.

Yet even with such mechanisms in play, genetic mutation rates for complex organisms such as humans are dramatically lower than the frequency of change for a host of traits, from adjustments in metabolism to resistance to disease. The rapid emergence of trait variety is difficult to explain just through classic genetics and neo-Darwinian theory. To quote the prominent evolutionary biologist Jonathan B L Bard, who was paraphrasing T S Eliot: ‘Between the phenotype and genotype falls the shadow.’

And the problems with Darwin’s theory extend out of evolutionary science into other areas of biology and biomedicine. For instance, if genetic inheritance determines our traits, then why do identical twins with the same genes generally have different types of diseases? And why do just a low percentage (often less than 1 per cent) of those with many specific diseases share a common genetic mutation? If the rate of mutation is random and steady, then why have many diseases increased more than 10-fold in frequency in only a couple decades? How is it that hundreds of environmental contaminants can alter disease onset, but not DNA sequences? In evolution and biomedicine, the rates of phenotypic trait divergence is far more rapid than the rate of genetic variation and mutation – but why?

Part of the explanation can be found in some concepts that Jean-Baptiste Lamarck proposed 50 years before Darwin published his work. Lamarck’s theory, long relegated to the dustbin of science, held, among other things, ‘that the environment can directly alter traits, which are then inherited by generations to come’. [Continue reading…]

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Watching evolution happen in two lifetimes

Emily Singer writes: When Rosemary and Peter Grant first set foot on Daphne Major, a tiny island in the Galápagos archipelago, in 1973, they had no idea it would become a second home. The husband and wife team, now emeritus biology professors at Princeton University, were looking for a pristine environment in which to study evolution. They hoped that the various species of finches on the island would provide the perfect means for uncovering the factors that drive the formation of new species.

The diminutive island wasn’t a particularly hospitable place for the Grants to spend their winters. At less than one-hundredth the size of Manhattan, Daphne resembles the tip of a volcano rising from the sea. Visitors must leap off the boat onto the edge of a steep ring of land that surrounds a central crater. The island’s vegetation is sparse. Herbs, cactus bushes and low trees provide food for finches — small, medium and large ground finches, as well as cactus finches — and other birds. The Grants brought with them all the food and water they would need and cooked meals in a shallow cave sheltered by a tarp from the baking sun. They camped on Daphne’s one tiny flat spot, barely larger than a picnic table.

Though lacking in creature comforts, Daphne proved to be a fruitful choice. The Galápagos’ extreme climate — swinging between periods of severe drought and bountiful rain — furnished ample natural selection. Rainfall varied from a meter of rain in 1983 to none in 1985. A severe drought in 1977 killed off many of Daphne’s finches, setting the stage for the Grants’ first major discovery. During the dry spell, large seeds became more plentiful than small ones. Birds with bigger beaks were more successful at cracking the large seeds. As a result, large finches and their offspring triumphed during the drought, triggering a lasting increase in the birds’ average size. The Grants had observed evolution in action.

That striking finding launched a prolific career for the pair. They visited Daphne for several months each year from 1973 to 2012, sometimes bringing their daughters. Over the course of their four-decade tenure, the couple tagged roughly 20,000 birds spanning at least eight generations. (The longest-lived bird on the Grants’ watch survived a whopping 17 years.) They tracked almost every mating and its offspring, creating large, multigenerational pedigrees for different finch species. They took blood samples and recorded the finches’ songs, which allowed them to track genetics and other factors long after the birds themselves died. They have confirmed some of Darwin’s most basic predictions and have earned a variety of prestigious science awards, including the Kyoto Prize in 2009.

Now nearly 80, the couple have slowed their visits to the Galápagos. These days, they are most excited about applying genomic tools to the data they collected. They are collaborating with other scientists to find the genetic variants that drove the changes in beak size and shape that they tracked over the past 40 years. Quanta Magazine spoke with the Grants about their time on Daphne; an edited and condensed version of the conversation follows. [Continue reading…]

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Tardigrades: The most fascinating animals known to science

 

Brian Resnick writes: Paul Bartels gets a rush every time he discovers a new species of tardigrade, the phylum of microscopic animals best known for being both strangely cute and able to survive the vacuum of space.

“The first paper I wrote describing a new species, there was a maternal-paternal feeling — like I just gave birth to this new thing,” he tells me on a phone call.

The rush comes, in part, because tardigrades are the most fascinating animals known to science, able to survive in just about every environment imaginable. “There are some ecosystems in the Antarctic called nunataks where the wind blows away snow and ice, exposing outcroppings of rocks, and the only things that live on them are lichens and tardigrades,” says Bartels, an invertebrate zoologist at Warren Wilson College in North Carolina.

Pick up a piece of moss, and you’ll find tardigrades. In the soil: tardigrades. The ocean: You get it. They live on every continent, in every climate, and in every latitude. Their extreme resilience has allowed them to conquer the entire planet.

And though biologists have known about tardigrades since the dawn of the microscope, they’re only just beginning to understand how these remarkable organisms are able to survive anywhere. [Continue reading…]

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Your gut bacteria predates appearance of humans, genetic study finds

The Guardian reports: The evolutionary history of the bacteria in your guts predates the appearance of humans, and mirrors that of our great ape relatives, according to a genetic study.

The research suggests that microbes in our ancestors’ intestines split into new evolutionary lineages in parallel with splits in the ape family tree.

This came as a surprise to scientists, who had thought that most of our gut bacteria came from our surroundings – what we eat, where we live, even what kind of medicine we take. The new research suggests that evolutionary history is much more important than previously thought.

“When there were no humans or gorillas, just ancestral African apes, they harboured gut bacteria. Then the apes split into different branches, and there was also a parallel divergence of different gut bacteria,” said Prof Andrew Moeller of the University of California, Berkeley who led the study, published in Science. This happened when gorillas separated somewhere between 10-15 million years ago, and again when humans split from chimps and bonobos 5 million years ago. [Continue reading…]

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‘Gene drives’ that tinker with evolution are an unknown risk, researchers say

MIT Technology Review reports: With great power — in this case, a technology that can alter the rules of evolution — comes great responsibility. And since there are “considerable gaps in knowledge” about the possible consequences of releasing this technology, called a gene drive, into natural environments, it is not yet responsible to do so. That’s the major conclusion of a report published today by the National Academies of Science, Engineering, and Medicine.

Gene drives hold immense promise for controlling or eradicating vector-borne diseases like Zika virus and malaria, or in managing agricultural pests or invasive species. But the 200-page report, written by a committee of 16 experts, highlights how ill-equipped we are to assess the environmental and ecological risks of using gene drives. And it provides a glimpse at the challenges they will create for policymakers.

The technology is inspired by natural phenomena through which particular “selfish” genes are passed to offspring at higher rate than is normally allowed by nature in sexually reproducing organisms. There are multiple ways to make gene drives in the lab, but scientists are now using the gene-editing tool known as CRISPR to very rapidly and effectively do the trick. Evidence in mosquitoes, fruit flies, and yeast suggests that this could be used to spread a gene through nearly 100 percent of a population.

The possible ecological effects, intended or not, are far from clear, though. How long will gene drives persist in the environment? What is the chance that an engineered organism could pass the gene drive to an unintended recipient? How might these things affect the whole ecosystem? How much does all this vary depending on the particular organism and ecosystem?

Research on the molecular biology of gene drives has outpaced ecological research on how genes move through populations and between species, the report says, making it impossible to adequately answer these and other thorny questions. Substantially more laboratory research and confined field testing is needed to better grasp the risks. [Continue reading…]

Jim Thomas writes: If there is a prize for the fastest emerging tech controversy of the century the ‘gene drive’ may have just won it. In under eighteen months the sci-fi concept of a ‘mutagenic chain reaction’ that can drive a genetic trait through an entire species (and maybe eradicate that species too) has gone from theory to published proof of principle to massively-shared TED talk (apparently an important step these days) to the subject of a US National Academy of Sciences high profile study – complete with committees, hearings, public inputs and a glossy 216 page report release. Previous technology controversies have taken anywhere from a decade to over a century to reach that level of policy attention. So why were Gene Drives put on the turbo track to science academy report status? One word: leverage.

What a gene drive does is simple: it ensures that a chosen genetic trait will reliably be passed on to the next generation and every generation thereafter. This overcomes normal Mendelian genetics where a trait may be diluted or lost through the generations. The effect is that the engineered trait is driven through an entire population, re-engineering not just single organisms but enforcing the change in every descendant – re-shaping entire species and ecosystems at will.

It’s a perfect case of a very high-leverage technology. Archimedes famously said “Give me a lever long enough and a fulcrum on which to place it, and I shall move the world. ” Gene drive developers are in effect saying “Give me a gene drive and an organism to put it in and I can wipe out species, alter ecosystems and cause large-scale modifications.” Gene drive pioneer Kevin Esvelt calls gene drives “an experiment where if you screw up, it affects the whole world”. [Continue reading…]

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