Tag: evolution

A Master Teller of Fish Stories

By Bob Holmes | May 21, 2018 8:00 am
A school of blue-striped grunt (Haemulon sciurus). As the name implies, this subtropical species makes a grunting sound that's generated when it grinds its teeth together. (Credit: Peter Leahy/Shutterstock)

A school of blue-striped grunt (Haemulon sciurus). As the name implies, this subtropical species makes a grunting sound that’s generated when it grinds its teeth together. (Credit: Peter Leahy/Shutterstock)

It has been called “the world’s most dangerous meal,” a fish whose internal organs are laced with one of the deadliest toxins on Earth. Specialized restaurants in Japan and a few other places serve carefully prepared fugu flesh as an expensive delicacy, in part because of this risky thrill.

But Byrappa Venkatesh was drawn to the fugu for an entirely different reason: It has the smallest genome of any vertebrate. That quality was gold back in the 1990s, when geneticists were still racing to sequence the human genome or that of any other vertebrate: Fugu offered a shortcut to the finish line. The puffer was still a slog, though. It cost Venkatesh and his colleagues nine years of hard work and about $10 million, and, in the end, the human genome project nosed them out, just barely, as the first vertebrate genome ever completed.

The puffer fish Fugu rubripes has the smallest genome of any vertebrate. It was the first fish species selected for genome sequencing. (Credit: javarman/Shutterstock)

The puffer fish Fugu rubripes has the smallest genome of any vertebrate. It was the first fish species selected for genome sequencing. (Credit: javarman/Shutterstock)

The project kindled a passion for fish genomics that has propelled Venkatesh ever since. With good reason: Fish are the most diverse group of vertebrates on the planet. They live in deep ocean, in acid waters and in Antarctic seas below the freezing point of blood. Their bodies range from eely, jawless lampreys to flattened flounders to huge, lumpish ocean sunfish. Some lay eggs, some bear live young, and in seahorses, it is the males that become pregnant. In short, fish are a geneticist’s dream. “They show so many variations,” says Venkatesh. “If there is any adaptation in any vertebrate, it should be there in fish.”

In the years since completing the fugu genome in 2002, Venkatesh — known universally as Venki — has sequenced the genomes of more than a dozen fishes, from sharks to the living-fossil coelacanth to his personal favorite, the seahorse. “He’s been a champion, in a very mild-mannered but persistent way, for a long time,” says Richard Durbin, a genomicist at the University of Cambridge. “He’s one of the focal persons for evolutionary fish genomics.”

Venkatesh has seen an enormous growth in sequencing power and technology since the early days of fugu. Today, generating a high-quality genome sequence from scratch takes just two months’ work and about $30,000. “Nobody predicted it would happen so fast,” he says. “You can sequence any genome now.”

And you can sequence lots of them. Venkatesh, based at Singapore’s Institute of Molecular and Cell Biology, helps lead a consortium with big ambitions to sequence hundreds of vertebrate genomes by the end of this decade, nearly half of them fish, en route to eventually completing sequences of every living vertebrate, and more.

A Student Takes the Bait

Despite his current prominence in genomics, Venkatesh came to the field almost by accident. Born in Bangalore, India, to a scientific family — his father was a veterinarian — he chose to study fisheries in university because it sounded like fun. “I thought I could go diving and have a great time,” he recalls.

He never did learn to dive. Instead, after a few years as a fisheries biologist in India, he headed off to Singapore for graduate school, where he studied the hormonal regulation of pregnancy in guppies.

(Credit: feathercollector/Shutterstock)

The ocean sunfish (Mola mola) has a strange, truncated back end. It also is the largest bony fish species in the world, with some adults weighing in at more than 2,000 pounds. Analysis of the sunfish genome reveals features that may explain its rapid growth rate and impressive size. (Credit: feathercollector/Shutterstock)

While there, he met Sydney Brenner of the University of Cambridge, one of the founders of molecular biology. Brenner wanted to be first to sequence a complete vertebrate genome and selected fugu for its tiny genome. He was looking for scientists to work with him on the project and saw something special in Venkatesh. “He said I should go join him in Cambridge,” says Venkatesh. “I had very little molecular biology background at that time, but he said it would be good for me.” Off he went to Cambridge, as the only fish expert on Brenner’s team.

In 1992, after Brenner left Cambridge for California, Venkatesh returned to Singapore to take up a job at the institute, bringing the fugu genome project with him. (Eventually Brenner, too, moved to Singapore, where he established his own lab next door to his protege’s. Now age 91, he still lives in Singapore and the two meet weekly for a drink or dinner.)

The fugu genome gave geneticists a valuable point of comparison to the human genome. They found that, despite its small size — just one-eighth the size of the human genome — the fugu has roughly the same complement of genes, and the on-off switches that control them, as humans do. To reach its slimline state, fugu seems to have lost many of the long, baffling stretches of DNA of unknown function — often called junk DNA — that litter most genomes. That made the fugu genome a helpful tool for separating the human genomic wheat from the chaff and especially for identifying the crucial regulatory switches, says Venkatesh. He later showed that the fugu’s regulatory switches are so similar to their mammalian counterparts that they can sometimes be swapped without loss of function.

Dipping Into the Shark Tank

Fresh from that success, Venkatesh turned his attention to other fish genomes. His first goal was to sequence a shark. Sharks lack bony skeletons, which indicates that they are an early branch in the evolutionary tree of vertebrates. Comparing their genes with those of bony fishes can thus shed new light on the evolution of higher fishes and their descendants, including humans.

But Venkatesh faced a big problem. Most sharks have huge genomes, far larger than those of humans, so they were difficult to sequence with the technology of the day. After two years of rummaging through the genomes of various shark species, he stumbled on the solution: the elephant shark, whose genome is only about a third the size of our own. “It’s the fugu among the sharks,” he says. That one, he could handle.

The elephant shark, Callorhinchus milii, is a genetic standout in two ways: Its genome is far smaller than that of most sharks and has changed far less over time than those of other vertebrates. (Credit: Fir0002/Flagstaffotos)

The elephant shark, Callorhinchus milii, is a genetic standout in two ways: Its genome is far smaller than that of most sharks and has changed far less over time than those of other vertebrates. (Credit: Fir0002/Flagstaffotos)

The sequencing, completed in 2007, revealed that the elephant shark is a living genomic fossil — it has changed less from its ancestral state than any other vertebrate known. “It’s like a screen shot of the past, how our ancestors looked,” says Venkatesh. “That makes it a very useful model for examining what changes have occurred.”

More genomes followed quickly, including those of the deep-sea coelacanth (one of the closest living relatives of terrestrial vertebrates) in 2013, the spotted gar (a primitive bony fish) in 2015, and the gigantic ocean sunfish and the distinctively shaped seahorse in 2016. Other research groups joined the hunt, so that by early 2018, Venkatesh could list 60 bony fish genomes completed by various labs around the world.

The genome of the spotted gar (Lepisosteus oculatus), a primitive bony fish, offers insights into the evolution of vertebrate development, gene control, immunity and tissue mineralization. (Credit: Sergey Lavrentev/Shutterstock)

The genome of the spotted gar (Lepisosteus oculatus), a primitive bony fish, offers insights into the evolution of vertebrate development, gene control, immunity and tissue mineralization. (Credit: Sergey Lavrentev/Shutterstock)

At the molecular level, fish turn out to be much more diverse than land vertebrates. Some time early in their evolution, bony fishes underwent a duplication of their entire genome. This freed up “spare” copies of genes for evolutionary tinkering without risking loss of the original gene function. This may explain why bony fish genomes have evolved more rapidly than those of their terrestrial cousins.

The Big Catch

Though Venkatesh finds fish fascinating in their own right, there is a larger prize in play as well. Humans and fish share most of the same molecular building blocks — their complement of genes — but deploy them in different ways. “You can take a pile of bricks and make a cathedral, you can make a bridge, you can make a villa, or you can make a road. The question is, what are the controlling mechanisms that take those bricks and make them into what you can see? That’s the big question,” says Edward Wiley, an ichthyologist at the University of Kansas. Because fish vary so much in body form, they make an ideal test bed to work out many of those controls, with big potential payoffs for our understanding of all vertebrates, including humans.

These and other genome studies are now coalescing into a systematic effort to sequence the greatest possible diversity of vertebrate life. Venkatesh is one of the leaders of this consortium, known as Genome 10K, and is playing a key role in identifying which fish to include. “Venki has been in on fish genomics since the beginning. When G10K was formed, it was natural that they would ask him to be responsible for the fishes,” says Wiley who, with Venkatesh, cochairs the effort’s fish section.

As its name suggests, G10K began with the goal of sequencing 10,000 vertebrate genomes, mostly in a rudimentary fashion. Since then, though, the group has refocused on quality over quantity: sequencing at least one genome from every major group, or order, of vertebrates — some 260 in all — using the newest, high-precision sequencing technology. The first hundred genomes should roll off the line within the next year, and the full set of 260 should be done by 2020, says Erich Jarvis, a genomic neurobiologist at Rockefeller University in New York City, who chairs the project. After that, the group has an even more ambitious goal: to sequence the genomes of every one of the 60,000-plus vertebrate species.

(Credit: Catmando/Shutterstock)

A coelacanth. The fish are from a lineage that was thought to have gone extinct 70 million years ago until a living specimen was discovered in the 1930s. The lineage is closely related to ancestral fish that gave rise to four-legged vertebrates. (Credit: Catmando/Shutterstock)

The technology is advancing so fast that a few genome biologists are talking of the ultimate goal: sequencing the genome of every species on Earth. The plan is not as far-fetched as it sounds. “There are something on the order of a million-and-a-half named species,” says Durbin. “We’ve probably sequenced on the order of a thousand. So there’s a thousandfold improvement to make. Typically, sequencing technologies are improving twofold a year. On that scale, in the next decade we’re going to be able to find the genomes of everything.”

If geneticists get anywhere close to that goal, current methods of sorting, comparing and understanding genomes will not cope with the enormous mass of data, says Gene Myers, a bioinformatician at the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden, Germany. But Myers is optimistic that researchers, in time, will solve that problem, just as they learned to handle the once-daunting data management challenge posed by the human genome. “Meeting these challenges is the fun part,” he says. “I want to be overwhelmed and figure it out.”

Working Away on DNA

Genome researchers will need help on another front, too, Venkatesh notes. Spelling out the genome of a species and picking out the genes it contains is relatively easy. Working out exactly what each gene actually does — and how variations in DNA sequence within the gene alter that — can be a much bigger challenge that involves a lot of detailed lab work. “You can sequence a genome in two months, but understanding the functional aspect of even one variant takes two years. We need to catch up on the functional study.”

Seahorses, such as the tiger tail seahorse Hippocampus comes, have a wealth of distinctive features; one of them, in males, is a specialized brood pouch where the embryos develop. (Credit: By Ekkapan Poddamrong.Shutterstock)

Seahorses, such as the tiger tail seahorse Hippocampus comes, have a wealth of distinctive features; one of them, in males, is a specialized brood pouch where the embryos develop. (Credit: Ekkapan Poddamrong/Shutterstock)

If geneticists can clear these hurdles — and if the consortium can find the funding to do the work — having a complete set of genomes could open whole new avenues of research. “Once you have the blueprints of all vertebrates on the planet, you’re going to be able to address questions that you could never address,” says Jarvis. Evolutionary biologists could track the genetic changes that underpin speciation — how a single cichlid species evolved into hundreds in Africa’s Lake Malawi, for example. Conservation biologists could more easily identify genetically distinct populations of threatened species or nonintrusively monitor their distribution from traces of DNA left in the environment. Someday, they may be able to understand the genetic reasons why some species are rare, and perhaps even resurrect extinct species from their genome sequences.

Human geneticists will get their payoff, too. With a complete set of genomes, they could reconstruct the evolutionary history of our own genome and trace the origin and function of each and every gene and on-off switch. “Once we have the complete sequences, we can start asking the question of how they’re regulated, and how that regulation or misregulation affects human health,” says Venkatesh, who has already begun exploring the genomic basis of some rare human diseases. “This is what I’d like to do in ten years, if I’m still around.”

CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: animals, evolution, genetics

Can Breathing Like Wim Hof Make Us Superhuman?

By Nathaniel Scharping | July 6, 2017 11:24 am
(Credit: Innerfire BV)

(Credit: Innerfire BV)

Take a deep breath. Feel the wave of nitrogen, oxygen and carbon dioxide press against the bounds of your ribcage and swell your lungs. Exhale. Repeat.

Before consciously inhaling, you probably weren’t thinking about breathing at all. The respiratory system is somewhat unique to our bodies in that we are both its passenger and driver. We can leave it up to our autonomic nervous system, responsible for unconscious actions like our heartbeat and digestion, or we can seamlessly take over the rhythm of our breath.

To some, this duality offers a tantalizing path into our subconscious minds and physiology. Control breathing, the thinking goes, and perhaps we can nudge other systems within our bodies. This is part of the logic behind Lamaze techniques, the pranayamic breathing practiced in yoga and even everyday wisdom — “just take a deep breath.”

These breathing practices promise a kind of visceral self-knowledge, a more perfect melding of mind and body that expands our self-control to subconscious activities. These may be dubious claims to some.

For Wim Hof, a Dutch daredevil nicknamed “The Iceman,” it is the basis of his success. Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts

When Did Sex Become Fun?

By Holly Dunsworth | September 30, 2016 10:41 am
shutterstock_416387254

The reproductive organs of a lily. (Bryan Neuswanger/Shutterstock)

(This post originally appeared in the online anthropology magazine SAPIENS. Follow @SAPIENS_org on Twitter to discover more of their work.) 

There are multiple answers to the question of where we come from: early hominins, monkeys, primordial goo, or the Big Bang, to name a few. Today’s answer, though, has probably, just a split second ago, popped into many readers’ minds. Today’s answer is sexual intercourse, a.k.a. “bleeping.” So let’s go back to the beginning, hundreds of millions of years before we invented euphemisms and censorship, and let’s ask: How in the evolutionary world did sex begin?

Algae, the green gunk that runs amok in our fish tanks, as well as the seaweed that stinks up our summer beaches, include some of the simplest sexually reproducing organisms on Earth. These lineages go back nearly 2 billion years. Algae do it. Plants do it. Insects do it. Even fungi do it. Much of this sex involves releasing sperm into the wind or the water so they can be carried to nearby eggs (as in mosses), relying on a different species to carry male gametes to female ones (many flowers), or maneuvering two bodies so that the openings to the internal reproductive organs are close enough together for fluid exchange (most insects and most birds). Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts

STDs Might Have Driven Us to Embrace Monogamy

By Rob Knell, Queen Mary University of London | April 13, 2016 2:17 pm
monogamy

(Credit: Ivan Galashchuk/Shutterstock)

Exactly why so many humans choose monogamous pair bonds over juggling multiple partners has long been a mystery to scientists. After all, having several partners at the same time should lead to more offspring — an outcome you’d think evolution would favor. Now a new study has linked the phenomenon to sexually transmitted diseases, arguing that monogamy could have evolved because it offered protection against the threat of infection.

Monogamy is, of course, the norm in Western societies. But there are many cultures where a husband can have more than one wife (polygyny) or, less commonly, a wife can have more than one husband (polyandry). This diversity of human mating systems is also hard to explain. What we do know, however, is that many hunter-gatherer societies, living in small groups, were most often polygynous (and many remaining groups still are). But with the rise of agriculture, societies tended to become more complex — and less polygynous. In the most strictly monogamous societies, there was often a social punishment for polygynists, either informally or, as in many modern societies, through a legal system. Read More

5 Extreme Examples of Evolutionary Prowess

By Marla Broadfoot | November 25, 2015 11:00 am
shutterstock_319478234

An illustration of the water bear. (Credit: Sebastian Kaulitzki/Shutterstock)

Hidden among us are survivors – living, breathing beings that have pulled off some pretty remarkable feats in order to live another day. They can be found ambling through the moss beneath our feet, drifting in our oceans and our streams, even stuck in the local pet store or on the subway. You just have to know where to look.

These creatures give clues into how we could withstand extreme conditions, regrow damaged tissue or missing limbs, turn back the hands of time, guard ourselves from illness, and perhaps even achieve humankind’s most elusive goal – immortality. Read More

CATEGORIZED UNDER: Living World, Top Posts

The Bloodthirsty Truth of the Beautiful Orchid Mantis

By James Gilbert, University of Sussex | January 27, 2015 11:05 am

orchid mantis

This article was originally published on The Conversation.

In his 1879 account of wanderings in the Orient, the travel writer James Hingston describes how, in West Java, he was treated to a bizarre experience:

I am taken by my kind host around his garden, and shown, among other things, a flower, a red orchid, that catches and feeds upon live flies. It seized upon a butterfly while I was present, and enclosed it in its pretty but deadly leaves, as a spider would have enveloped it in network.

What Hingston had seen was not a carnivorous orchid, as he thought. But the reality is no less weird or fascinating. He had seen – and been fooled by – an orchid mantis, Hymenopus coronatus, not a plant but an insect.

We have known about orchid mantises for more than 100 years. Famous naturalists such as Alfred Russell Wallace have speculated about their extraordinary appearance. Eschewing the drab green or brown of most mantises, the orchid mantis is resplendent in white and pink. The upper parts of its legs are greatly flattened and are heart-shaped, looking uncannily like petals. On a leaf it would be highly conspicuous – but when sitting on a flower, it is extremely hard to see. In photos, the mantis appears in or next to a flower, challenging the reader to spot it.

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CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: animals, evolution

Are We “Meant” to Have Language and Music?

By Mark Changizi | March 15, 2012 8:31 am

Mark Changizi is an evolutionary neurobiologist and director of human cognition at 2AI Labs. He is the author of The Brain from 25000 FeetThe Vision Revolution, and his newest book, Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man.”

What do ironing and hang-gliding have in common? Not much really, except that we weren’t designed to do either of them. And that goes for a million other modern-civilization things we regularly do but are not “supposed” to do. We’re fish out of water, living in radically unnatural environments and behaving ridiculously for a great ape. So, if one were interested in figuring out which things are fundamentally part of what it is to be human, then those million crazy things we do these days would not be on the list.


iStockphoto

But what would be on the list?

At the top of the list of things we do that we’re supposed to be doing, and that are at the core of what it is to be human rather than some other sort of animal, are language and music. Language is the pinnacle of usefulness, and was key to our domination of the Earth (and the Moon). And music is arguably the pinnacle of the arts. Language and music are fantastically complex, and we’re brilliantly capable at absorbing them, and from a young age. That’s how we know we’re meant to be doing them, i.e., how we know we evolved brains for engaging in language and music.

But what if this gets language and music all wrong? What if we’re not, in fact, meant to have language and music? What if our endless yapping and music-filled hours each day are deeply unnatural behaviors for our species? (What if the parents in Footloose* were right?!)

I believe that language and music are, indeed, not part of our core—that we never evolved by natural selection to engage in them. The reason we have such a head for language and music is not that we evolved for them, but, rather, that language and music evolved—culturally evolved over millennia—for us. Our brains aren’t shaped for these pinnacles of humankind. Rather, these pinnacles of humankind are shaped to be good for our brains.

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CATEGORIZED UNDER: Mind & Brain, Top Posts

Why Calorie Counts Are Wrong: Cooked Food Provides a Lot More Energy

By Richard Wrangham | December 8, 2011 9:10 am

by Richard Wrangham, as told to Discover’s Veronique Greenwood. Wrangham is the chair of biological anthropology at Harvard University, where he studies the cultural similarities between humans and chimpanzees—including our unique tendencies to form murderous alliances and engage in recreational sexual activity. He is the author of Catching Fire: How Cooking Made Us Human

When I was studying the feeding behavior of wild chimpanzees in the early 1970s, I tried surviving on chimpanzee foods for a day at a time. I learned that nothing that chimpanzees ate (at Gombe, in Tanzania, at least) was so poisonous that it would make you ill, but nothing was so palatable that one could easily fill one’s stomach. Having eaten nothing but chimpanzee foods all day, I fell upon regular cooked food in the evenings with relief and delight.

About 25 years later, it occurred to me that my experience in Gombe of being unable to thrive on wild foods likely reflected a general problem for humans that was somehow overcome at some point, possibly through the development of cooking. (Various of our ancestors would have eaten more roots and meat than chimpanzees do, but I had plenty of experience of seeing chimpanzees working very hard to chew their way through tough raw meat—and had even myself tried chewing monkeys killed and discarded by chimpanzees.) In 1999, I published a paper [pdf] with colleagues that argued that the advent of cooking would have marked a turning point in how much energy our ancestors were able to reap from food.

To my surprise, some of the peer commentaries were dismissive of the idea that cooked food provides more energy than raw. The amazing fact is that no experiments had been published directly testing the effects of cooking on net energy gained. It was remarkable, given the abiding interest in calories, that there was a pronounced lack of studies of the effects of cooking on energy gain, even though there were thousands of studies on the effects of cooking on vitamin concentration, and a fair number on its effects on the physical properties of food such as tenderness. But more than a decade later, thanks particularly to the work of Rachel Carmody, a grad student in my lab, we now have a series of experiments that provide a solid base of evidence showing that the skeptics were wrong.

Whether we are talking about plants or meat, eating cooked food provides more calories than eating the same food raw. And that means that the calorie counts we’ve grown so used to consulting are routinely wrong. Read More

The Driver of Human Evolution Isn’t the Climate Around You, It’s the Worms Inside You

By Razib Khan | December 2, 2011 11:58 am


One of the strangest aspects of our understanding of evolutionary biology is the tendency to conflate a sprawling protean dynamic into a sliver of a phenomenon. Most prominently, evolution is often reduced to a process driven by natural selection, with an emphasis on the natural. When people think of populations evolving they imagine them being buffeted by inclement weather, meteors, or smooth geological shifts. These are all natural, physical phenomena, and they all apply potential selection pressures. But this is not the same as evolution; it’s just one part. A more subtle aspect of evolution is that much of the selection is due to competition between living organisms, not their relationship to exterior environmental conditions.

The question of what drives evolution is a longstanding one. Stephen Jay Gould famously emphasized of the role of randomness, while Richard Dawkins and others prioritize the shaping power of natural selection. More finely still, there is the distinction between those which emphasize competition across the species versus within species. And then there are the physical, non-biological forces.

Evolution as selection. Evolution as drift. Evolution as selection due to competition between individuals of the same species. Evolution as selection due to competition between individuals of different species. And so forth. There are numerous models, theories, and conjectures about what’s the prime engine of evolution. The evolutionary biologist Richard Lewontin famously observed that in the 20th century population geneticists constructed massively powerful analytic machines, but had very little data which they could throw into those machines. And so it is with theories of evolution. Until now.

Over the past 10 years in the domain of human genetics and evolution there has been a swell of information due to genomics. In many ways humans are now the “trial run” for our understanding of evolutionary process. Using theoretical models and vague inferences from difficult-to-interpret signals, our confidence in the assertions about the importance of any given dynamic have always been shaky at best. But now with genomics, researchers are testing the data against the models.

A recent paper is a case in point of the methodology. Using 500,000 markers, ~50 populations, and ~1,500 people, the authors tested a range of factors against their genomic data. The method is conceptually simple, though the technical details are rather abstruse. The ~1,500 individuals are from all around the globe, so the authors could construct a model where the markers varied as a function of space. As expected, most of the genetic variation across populations was predicted by the variation across space, which correlates with population demographic history; those populations adjacent to each other are likely to have common recent ancestors. But the authors also had some other variables in their system which varied as a function of space in a less gradual fashion: climate, diet, and pathogen loads. The key is to look for those genetic markers and populations where the expectation of differences being driven as a function of geography do not hold. Neighbors should be genetically like, but what if they’re not? Once you find a particular variant you can then see how it varies with the factors listed above.

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CATEGORIZED UNDER: Living World, Top Posts

White Nose, Black Death—Context Makes a Killer

By John Rennie | November 7, 2011 5:41 pm

Consider two pandemics: the white-nose syndrome now devastating North American bats and the Black Death that killed a third or more of Europeans in the 14th century. Lethality aside, they may not seem to have much in common. But recent studies suggest they both offer important lessons about understanding that the deadliness of disease organisms is very much a product of the circumstances in which they appear.

Two weeks ago in Nature, a multi-institutional team of U.S. Geological Survey scientists presented conclusive evidence the parasitic fungus that lends white-nose syndrome its name is indeed the cause of the mysterious bat epidemic. The illness came to light in New York in 2006, when cave explorers started finding thousands of little brown bats (and later, other species) dead together in the caves where they spent the winter months, their bodies covered with a white fungus, Geomyces destructans. It has since spread throughout the northeastern U.S., where bat populations have declined on average by 73 percent—which may make it one of the most rapid declines in wildlife populations ever observed. Worse, white-nose syndrome is still on the move, with documented cases in four Canadian provinces and states as far south and west as Tennessee, Missouri, and Oklahoma.

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