Arquivo da tag: Biologia

Has a marine mammal conservation program become too successful? (Slate)

Great White Sharks Are Back

By |Posted Tuesday, July 2, 2013, at 4:05 PM

Great white shark.

Today, a great white shark sighting is more likely to elicit curiosity than fear. Cape Cod sharks even have their own advocacy group. Photo by Steven Benjamin/iStockphoto/Thinkstock

When a tourist from Colorado was bitten by a great white shark last summer while swimming off Cape Cod, an excited media made predictable comparisons to the 1975 blockbuster Jaws. The 50-year-old man, who was fortunate to survive with bites to his legs but with all his limbs still attached, was the first human to be attacked by a shark in Massachusetts waters since 1936. As more sighting reports poured in, 2012 became Cape Cod’s “Summer of the Shark.”

We all love a good shark scare, but in this case the coverage wasn’t completely exaggerated. In 1974, when Jaws was filmed just off the cape on Martha’s Vineyard, great white sharks—known to marine biologists simply as white sharks—were rare, with one or two spotted in New England waters each year. In 2012, there were more than 20 confirmed sightings at Cape Cod beaches, and so far this summer two beaches have been closed temporarily after the sharks’ telltale dorsal fins were seen just offshore. Scientists have now tagged 34 great whites off of Cape Cod, and the data show the minivan-size fish sticking to a clear migration pattern—down south or out to sea in the winter and, like the Kennedys, back to the cape every summer.

Jaws aside, these sharks are not hunting unsuspecting vacationers. They’re after seals, which have soared in population in recent years thanks to a national conservation effort that has proven enormously successful—some might say too successful. The shark resurgence comes down to simple food chain economics, but it also shows how wildlife conservation can sometimes have weird and unpredictable consequences.

Seals have a tendency to hang around boats and snatch fish from nets, and for centuries people fishing off New England would kill any seal they saw. Between the late 19thcentury and the early 1960s, the state of Massachusetts offered a bounty of up to $5 for every pinniped slaughtered. By 1972, harbor seals, once common on Cape Cod, were becoming rarer, and gray seals were all but wiped out. But that year Congress passed the Marine Mammal Protection Act, a law that forbids the killing, capture, or harassment of whales, dolphins, polar bears, manatees, seals, and similar animals—creatures that commercial hunting and other human activity had taken, in some cases, to the brink of extinction.

The act has been a tremendous success. In March 2011, a one-day count of gray seals in Massachusetts waters found 15,756 of them, compared to 5,611 in 1999. The National Oceanic and Atmospheric Administration estimates that the gray seal population in the Western Atlantic grew annually between 6 and 9 percent during the past three decades. Today, seals haul out and lounge on some beaches in enormous numbers, and it’s common to see them swimming alone or in pairs up and down the Atlantic side of Cape Cod. That’s a lot of shark bait. One recent afternoon at Nauset Light Beach, part of the Cape Cod National Seashore, I stood on the sand with a group of beachgoers watching a sleek brown head bobbing just past the breakers. Having been warned by prominent signs not to swim near seals, none of us were going near the water. “Does this mean there are sharks out there?” one woman asked, in a tone that revealed both anxiety and fascination.

Tourism is Cape Cod’s main industry, with domestic visitors spending some $850 million in 2011, and locals worry that if anyone were to be killed or badly hurt by a shark, tourists might start to avoid cape beaches. In an effort to educate people about shark safety, beach authorities have erected notice boards, and towns are using a $50,000 state grant to print brochures with helpful shark safety tips—chief among them, “Avoid swimming near seals.” Looking to South Africa, which has been dealing with great white sharks for years, Cape Cod officials have talked about setting up a system for shark detection, perhaps by using spotter planes or installing more acoustic buoys to track tagged sharks. But so far there isn’t enough funding for a major effort.

Seals are taking the blame for luring sharks, and at the same time the old resentment is flaring up among some fishermen, who say seals are harming the cape’s struggling fishing industry. Gordon Waring, a seal specialist at the NOAA, cautions that marine biologists don’t actually know how seals interact with fisheries, and so far there is no sign that they are eating more than their habitat can support. But it is clear that seals are attracted to fishing boats and piers, and fishermen who watch seals stealing fish from their nets justifiably resent the greedy creatures, which the Marine Mammal Protection Act says can’t even be shooed away (that would be “harassment”). Fish stocks, particularly of cod, are down, and while that’s mostly due to other factors such as decades of overfishing, seals are a visible target for blame. There has even been talk of a seal cull, and a Nantucket-based group calling itself the Seal Abatement Coalition is lobbying Congress to remove gray seals from the list of species covered by the Marine Mammal Protection Act. Seal culls are already a regular occurrence in Canada, which has historically had much larger seal populations.

That might all sound like we’re headed for a return to the era when seals were shot on sight and sharks stalked and killed to protect swimmers, but in truth there are heartening signs that humans’ relationship with ocean life off Cape Cod will be better this time around. While a horror movie starring an animatronic shark could once keep people out of the water all summer, today, a great white sighting is more likely to elicit curiosity than fear. Cape Cod sharks even have their own advocacy group.

Gray seal hanging around at the Chatham Fishing Pier.Seals have a tendency to hang around boats and snatch fish from nets. Courtesy of Amy Crawford

“As tragic as a shark attack is, it would be more tragic not to have sharks in our oceans,” says Cynthia Wigren, who last summer helped found the Atlantic White Shark Conservancy, a Cape Cod group (with an adorable smiling shark logo) that raises money for education and research. Greg Skomal, a shark biologist with the Massachusetts Division of Marine Fisheries, has been leading an effort to tag great whites and study their migration patterns. He sees the sharks’ return as an indication that the marine ecosystem off New England is returning to normal, with sharks playing a crucial role as apex predators. That’s great news, ecologically speaking. But as he points out, “That does not take into consideration the negative impacts that can occur with the restoration of a natural ecosystem.”

Sharks are not the brightest animals in the sea. Humans are not a preferred prey animal, but sharks looking for seals sometimes get confused. Given that their primary way of interacting with the world is to use their mouths (in a way, maybe they are the “mindless eating machines” of the Jaws trailer), a shark may give a human swimmer a good “gumming,” Skomal says, before realizing it hasn’t found a seal. “If sharks wanted to eat humans, we’d have a hell of a lot more shark attacks,” Skomal says. “These are instinctive wild animals, and they make mistakes every now and then. It’s extremely rare, but nonetheless they make mistakes.”

While a great white shark’s honest mistake can still be terrifying—just ask that tourist who got bitten last summer—sharks’ public image seems to be evolving as conservationists educate people about the need to protect vulnerable species and as our understanding of nature becomes more sophisticated. We may be learning to adapt to nature, rather than forcing it to adapt to us.

Nowhere is that more apparent than in Chatham, a 300-year-old fishing village on the elbow of Cape Cod that has found itself at the epicenter of the wildlife resurgence. InJaws, small town leaders tried to cover up shark attacks, fearing they would be bad for business. But Lisa Franz, director of Chatham’s Chamber of Commerce, says the opposite has been true—at least so long as no one has been seriously hurt. While the local fishing industry is struggling, other businesses are capitalizing on people’s curiosity about sharks and the seals they feast on. Shark T-shirts and stuffed toys are flying off gift shop shelves, and there’s talk of making Chatham an ecotourism destination.

“When the first shark hits the newspapers, we get busier earlier,” says Keith Lincoln, who runs a Chatham cruise business that specializes in seal tours. His “office,” parked recently in a lot at the Monomoy National Wildlife Refuge, is a Honda Odyssey with an inflatable shark strapped to the roof—“a hit with the tourists,” he says. But while passengers might say they want to see sharks, Lincoln is not sure they know what they’re getting into. He has seen great whites swimming near the beach, their huge forms casting dark shadows on the sand below. “We usually don’t tell people,” he says. “They leave here all brave, but when they see a fish that’s as big as the boat, they’re not so brave.”

Then again, he might just need a bigger boat.

Watch Discovery Channel’s joking take on the shark frenzy for seals here.

The Worst Marine Invasion Ever (Slate)

I could not believe what I found inside a lionfish.

By Christie Wilcox |Posted Monday, July 1, 2013, at 7:00 AM

A Lionfish swims in a display tank in the aquarium on the United Arab Emirate of Sharjah on August 6, 2008.

A lionfish in an aquarium. Photo by Alexander Klein/AFP/Getty Images

“Do you know what this is?” James Morris looks at me, eyes twinkling, as he points to the guts of a dissected lionfish in his lab at the National Ocean Service’s Center for Coastal Fisheries and Habitat Research in Beaufort, N.C. I see some white chunky stuff. As a Ph.D. candidate at the Hawaii Institute of Marine Biology, I should know basic fish biology literally inside and out. When I cut open a fish, I can tell you which gross-smelling gooey thing is the liver, which is the stomach, etc.

He’s testing me, I think to myself. Morris is National Oceanic and Atmospheric Administration’s pre-eminent scientist studying the invasion of lionfish into U.S. coastal waters. He’s the lionfish guy, and we met in person for the first time just a few days earlier. We’re processing lionfish speared by local divers, taking basic measurements, and removing their stomachs for ongoing diet analyses. Not wanting to look bad, I rack my brain for an answer to his question. It’s not gonads. Not spleen. I’m frustrated with myself, but I simply can’t place the junk; I’ve never seen it before. Finally, I give up and admit that I’m completely clueless.

Close-up on the insides of an obese North Carolinian lionfish.

Close-up on the insides of an obese North Carolinian lionfish. Photo by Christie Wilcox

“It’s interstitial fat.”

“Fat?”

“Fat,” he says firmly. I look again. The white waxy substance hangs in globs from the stomach and intestines. It clings to most of the internal organs. Heck, there’s got to be at least as much fat as anything else in this lionfish’s gut. That’s when I realize why he’s pointing this out.

“Wait … these lionfish are overweight?” I ask, incredulous.

“No, not overweight,” he says. “Obese.” The fish we’re examining is so obese, he notes, that there are even signs of liver damage.

Obese. As if the lionfish problem in North Carolina wasn’t bad enough.

Though comparing invasions is a lot like debating if hurricanes are more devastating than earthquakes, it’s pretty safe to say that lionfish in the Atlantic is the worst marine invasion to date—not just in the United States, but globally. Lionfish also win the gold medal for speed, spreading faster than any other invasive species. While there were scattered sightings from the mid-1980s, the first confirmation that lionfish were becoming established in the Atlantic Ocean occurred off of North Carolina in 2000. Since then, they have spread like locusts, eating their way throughout the Caribbean and along every coastline from North Carolina to Venezuela, including deep into the Gulf of Mexico. When lionfish arrive on a reef, they reduce native fish populations by nearly 70 percent. And it’s no wonder—the invasive populations are eight or more times as dense than those in their native range, with more than 450 lionfish per hectare reported in some places. That is a lot of lionfish.

These alien fish didn’t just come here on their own. Early guesses as to how the lionfish arrived ranged from ships’ ballast water to the coastal damage caused by Hurricane Andrew, but now scientists are fairly sure that no ships or natural disasters are to blame. Instead, it’s our fault. Pretty, frilly fins made the fish a favored pet and lured aquarists and aquarium dealers into a false sense of security. We simply didn’t see how dangerous these charismatic fish were—dangerous not for their venom, but for their beauty. We have trouble killing beautiful things, so instead we choose to release them into the wild, believing somehow that this is a better option when, in actuality, it’s the worst thing we can do. Released animals rarely survive in the harsh real world, but it’s even worse when they do. Pet releases and escapees have become problematic invaders all over the country, from the ravenous pythons in Florida to the feral cats of Hawaii. In the case of lionfish, multiple releases from different owners likely led to enough individuals to start an Atlantic breeding population. Rough genetic estimates suggest that fewer than a dozen female fish began what may go down in history as the worst marine invasion of all time.

Lots, and lots, of lionfish caught by the Discovery Diving crew on one day.

Lots and lots of lionfish caught by the Discovery Diving crew on one day. Courtesy of Discovery Diving

In North Carolina, the lionfish invasion can be seen at its worst. Offshore, where warm waters from the Gulf Stream sweep up the coast, the lionfish reign. Local densities increased 700 percent between 2004 and 2008. I got to witness the unfathomable number of lionfish firsthand when I dove with the crew of Discovery Diving, a local scuba shop, to compete in North Carolina’s inaugural lionfish derby. I’ve never seen so many lionfish in my life. I didn’t get more than 20 yards from my starting point before I saw hundreds—literally, hundreds. My spear couldn’t fly fast enough to catch them all. On the last day of the tournament, a six-diver team bagged 167 lionfish from one site in two dives, and they didn’t even make a dent in the population on that wreck site. Morris estimates that more than 1,000 lionfish are at this site. Let me tell you, this is what an invasion looks like. An ecological cascade has been set in motion by these Indo-Pacific fish, and scientists are frantically gathering data, learning as much as they can to understand the extent of the damage lionfish will inflict, and figuring out the best responses to protect these fragile marine ecosystems.

Despite the destruction, it’s hard not to be impressed by these colorful aliens. Part of me holds lionfish in the highest regard, with a sort of evolutionary awe. They’re an incredible fish. Given complete creative freedom, I cannot imagine a way to design a marine species more suited to dominance. Sure, they might not be at the top of the food chain like sharks or killer whales, but what they lack in size they make up for in adaptability and reproductive output. The key to their Darwinian success is that they grow fast, mature early, and breed year-round. A single female can release upward of 2 million eggs annually that become larvae capable of floating along currents for more than a month, dispersing for hundreds to thousands of miles. They’ll eat whatever they can get their mouths around, which happens to be any fish or invertebrate just a hair smaller than they are, and they can grow to more than 18 inches long. That means young fish and crustaceans of any species that live where lionfish do are potential targets. And, to top it all off, they are armed with a formidable set of long, sharp venomous spines capable of inducing incapacitating pain. Not surprisingly, nothing seems inclined to eat them. They’re known for their cavalier attitude toward divers, ignoring our presence or possessing the gall to approach us head on, even in the face of a spear. Their cocky resolve is admirable. It’s abundantly clear that these fish fear nothing, not a hungry grouper, not the largest of reef sharks, not even the most effective predators on the planet—us.

Christie Wilcox cutting open a lionfish to remove its stomach.

The author cuts open a lionfish to remove its stomach. Photo by NOAA intern Dave Matthews

Of course, we are perhaps the only animal that lionfish should be fearful of, the only species potentially capable of controlling lionfish populations. Scientists, managers, fishermen, and locals from Venezuela to North Carolina are rallying behind “Eat Lionfish” campaigns. Lionfish tournaments have become annual events in some of the most heavily hit areas of the Caribbean and Atlantic. The Reef Environmental Education Foundation released a lionfish cookbook in 2010 to spur culinary interest and inform fishermen and chefs how to clean and prepare this new delicacy. But even with a serious fishery throughout the invasive range, we will likely never evict lionfish from their new homes. Studies have suggested that we’d need to fish more than a quarter of the mature lionfish every month to stunt population growth, let alone reverse it. Our best hope is to keep local populations low enough to protect key commercial and ecological species, a mission that is proving to be harder and harder as we realize just how much lionfish eat.

We’ve always known that lionfish are formidable predators. As slow-moving fish, they have to be pretty effective hunters to get away with such flamboyant looks. After all, it’s not like their prey won’t see them coming. They practically advertise their presence, waving around their frilly, striped fins with a level of arrogance usually reserved for apex predators. In their native range, young fish run from the sight. But in the Atlantic, native fish have never seen such a bizarre-looking predator. They don’t realize that this colorful display is a warning, not only of their potent venom but also of a nearly insatiable appetite. They don’t flee, and they get eaten. And in North Carolina, the lionfish are eating so well they’ve become fat. No, not fat. Obese.

As James Morris and I measured and sliced 247 fish last month, he explained that we have to monitor their diets to understand how lionfish may impact native fish.

So far, more than 70 different species have been found in the stomachs of invasive lionfish, but detailed data on what they regularly eat in many different areas and throughout the year hasn’t been collected—yet. That’s one of the questions Morris is in the process of answering, and that’s what I helped him with while I was in North Carolina collecting samples for my own research on lionfish venom.

The coast of North Carolina is renowned for its seafood. Cold waters from the north and the warm Gulf Stream converge at Cape Hatteras, creating some of the richest fishing grounds on the Eastern Seaboard. More than 60 million pounds of fish and shellfish are pulled out of its waters every year, worth upward of $1 billion to commercial fishermen. Lionfish are eating a lot of something, and if these gluttons are eating key commercial species, there could be a negative ripple effect on the local economy.

Vermilion snapper pulled from a lionfish's stomach.

Vermilion snapper pulled from a lionfish’s stomach. Courtesy of NOAA

One species Morris is particularly concerned about is the vermillion snapper. One of the smallest of the species often labeled as red snapper, vermilion snapper are the most frequently caught snapper along the southeastern United States. Because of their popularity, vermilion snapper populations are closely monitored, and their harvest has been managed in a variety of ways, including limited entry systems, annual quotas, size limits, trip limits, and seasonal closures. So far, government assessments say that the populations are not overfished, but fisheries-watch organizations such as the Monterey Bay Aquarium aren’t convinced. What we know for certain is that vermillion snapper are among the most heavily managed fish in North Carolina, and all of our efforts will be for naught if the lionfish are getting to them first.

So far, it’s not looking good.

I personally pulled vermillion snapper out of lionfish guts last month, along with tomtates and various other reef fish. It’s estimated that lionfish in the Bahamas eat upward of 1,000 pounds of prey per acre per year. Given that lionfish feed largely on small fishes, this equates to hundreds of thousands of individual fish consumed per year by lionfish per acre. But all the interstitial fat I saw suggests that the North Carolinian fish aren’t just eating until they’re full; they’re overindulging on the rich diversity of seafood that North Carolina has to offer. Though lionfish can go weeks between meals, when they don’t have to, they won’t. Scientists have observed lionfish eating at a rate of one to two fish per minute, and their stomachs can expand 30 times their size to accommodate lots of food. To become obese, fish eat upward of 7.5 times their normal dietary intake, which means the abundant North Carolina lionfish could be eating as much as 7,000 pounds of prime North Carolina seafood per acre every year—seafood that we’d much prefer ended up on our plates instead.

In 2010 scientists named the lionfish invasion one of the top 15 threats to global biodiversity. In the three years since, the invasion has only worsened. The only solution is to fight fire with fire, or in this case, pit our bottomless stomachs against theirs. We really do have to eat them to beat them.

Unfortunately, developing a fishery for lionfish isn’t as straightforward as it sounds. They don’t tend to bite hooks and live in complex habitats like reefs and wrecks that can’t be fished with large nets. To catch them, people have to get in the water and spear them one by one—an expensive and tedious way to fish. For lionfish fisheries to turn a profit, demand will have to be high and constant. So far, only a handful of local restaurants have taken the bait, enticing locavores with a truly sustainable menu option. Their business alone isn’t enough, though, to really drive a market.

That’s even assuming that lionfish are completely safe to eat. Recently, the Food and Drug Administration raised flags about lionfish—but not because of their venom. They are concerned that lionfish may contain ciguatoxin, a common tropical poison that causes somewhere between 50,000 and 500,000 cases of ciguatera fish poisoning every year. Ciguatera isn’t unique to lionfish; the disease occurs in tropical waters worldwide. The small lipid ciguatoxins that cause it are made by dinoflagellates, microscopic algaelike animals that live on and near reefs. Animals don’t really break down ciguatoxin, so it bioaccumulates up the food chain, thus large predators that eat high on the food web are most likely to have dangerous levels of ciguatoxin. In areas where the disease is endemic, species such as groupers and barracuda are simply too risky to consume and are often avoided by fishermen. The FDA is concerned that lionfish should also be included on that list, meaning that in areas such as the Virgin Islands, lionfish would be permanently off the menu. Their press release stated that more than a quarter of lionfish sampled contained unsafe ciguatoxin levels, and it issued a warning against eating them.

To other scientists, including myself, the news is baffling. I haven’t seen the actual data (because the FDA has yet to release them), but such high numbers just seem unbelievable. Thousands of lionfish are eaten every year after tournaments, and there hasn’t been a single case of ciguatera from a lionfish. If so many are dangerous, why hasn’t anyone gotten sick? And even if some areas do have ciguatoxic lionfish, surely other areas are safe. After all, we can still eat grouper and other predators from much of the Atlantic and Caribbean. Lionfish shouldn’t be more ciguatoxic than other reef fish—not unless their diet is very, very different.

One of the tough things about ciguatoxin is that we don’t have reliable, direct tests for it. There is a diverse set of indirect assays, all with different methods, different detection levels, and different specificities. All of this makes it hard to compare studies done by different labs and hard to ensure accuracy. Top that off with a species that has never been tested for ciguatoxin before, and things get really messy. This is where my research comes in.

Lionfish possess potent venom that activates sodium channels on the surface of nerve cells, causing a massive influx of calcium. This leads to the release and depletion of the neurotransmitter acetylcholine. This happens to be the exact same thing ciguatoxin does. Which, to me, raises a very important question: What if lionfish venom is getting into ciguatoxin assays? Are venom compounds causing false positives? The venom itself, though excruciating in the form of a sting, is harmless on the plate. Unlike ciguatoxin, it’s readily degraded by heat, so if it is venom and not ciguatoxin causing positive tests, lionfish may be safer to eat than the FDA data suggest. Hopefully, the samples I collected on this trip to North Carolina—where ciguatoxin isn’t an issue—will provide some answers.

James Morris pulling a lionfish's stomach for gut content analyses.

James Morris pulling a lionfish’s stomach for gut content analyses. Courtesy of NOAA

Until we know more, though, promoting fisheries is a potentially dangerous management strategy, at least in certain areas. Some governments have stepped in to promote hunting even without a formal fishery plan, in an attempt to protect their reefs’ future. But many of the small, developing countries in the Caribbean simply don’t have the resources to fund large-scale lionfish removal efforts. For them, steady fisheries would be the only way to get fishermen to catch lionfish instead of currently lucrative species such as grouper.

While we wait to see whether we can drum up the demand, the lionfish are making themselves comfortable. They’re embedding themselves in already fragile ecosystems, restructuring food webs, and pushing reefs toward irreversible ecological cascades. They’re exploring new habitats, discovering the rich resources provided by seagrass meadows and mangroves, even travelling miles inland and upstream in Florida. They’re taking over reefs, wrecks, and rocky territory from the surface to more than 800 feet deep, and they’re gorging themselves on whatever young fish happen to live there. They are, quite literally, growing fat off of our inaction.

That’s not to say there is no hope. Yes, we’re going to have to learn to live with the lionfish. We’re going to have to accept their presence in the Atlantic, Caribbean, and Gulf of Mexico, but we can use science to arm us against this invasion. In the quiet lab in North Carolina, Morris isn’t just studying fish. He’s preparing us for battle. In this endless war with a formidable foe, knowledge truly is power. The power to predict. The power to pre-empt. The power to fight back and save the species we value most. The power to educate and rally reinforcements to drive back invaders. The more we know about the lionfish, the better our strategies will be to deal with them and future invaders and the better our chances of success. The lionfish caught us by surprise, but Morris isn’t going to let them stay one step ahead. Even if we can’t eradicate these gluttonous fish, we may be able to manage them and minimize the damage they do to our precious marine ecosystems.

Considering it’s our fault that lionfish are here in the first place, it’s really a war against ourselves: against our bad habits, against our casual disregard for the ecosystems that protect and sustain us, against the attitudes and mindsets that led to such a devastating invasion to begin with. It’s a war that, as a nation, as a species, we cannot afford to lose. And one thing is for certain: With so much at stake, it’s going to be a bloody one.

Controversial Worm Keeps Its Position as Progenitor of Humankind (Science Daily)

Xenoturbella bocki worm. (Credit: Hiroaki Nakano)

Mar. 27, 2013 — Researchers are arguing about whether or not the Xenoturbella bocki worm is the progenitor of humankind. But new studies indicate that this is actually the case.

Swedish researchers from the University of Gothenburg and the Gothenburg Natural History Museum are involved in the international study. The results have been published in Nature Communications.

The Xenoturbella bocki worm is a one-centimetre long worm with a simple body plan that is only found regularly by the west coast of Sweden. The worm lacks a brain, sexual organs and other vital organs.

Zoologists have long disagreed about whether or not the Xenoturbella bocki worm holds a key position in the animal tree of life. If it does have a key position, it is very important for the understanding of the evolutionary development of organs and cell functions, such as stem cells, for example. The question is therefore not only important in the field of biology, but also for potential biomedical applications.

“It’s absolutely fantastic that one of the key evolutionary organisms in the animal kingdom lives right on the doorstep of the University of Gothenburg’s Centre for Marine Research. And this is actually the only place in the whole world where you can do research on the creature,” says Matthias Obst from the Department of Biological and Environmental Sciences at the University of Gothenburg.

Genetic studies indicate that theXenoturbella bocki worm belongs to the group of deuterostomes, the exclusive group to which human’s belongs.

“So maybe we’re more closely related to the Xenoturbella bocki worm, which doesn’t have a brain, than we are to lobsters and flies, for example,” says Matthias Obst.

Even though the worm does not particularly resemble man, development biologists have referred to the fact that the early embryonic development of the worm may display similarities with the group to which man belongs. But the problem has been that no one has previously been able to see the development of the creature.

But now a group of researchers at the Sven Lovén Centre for Marine Sciences and the Gothenburg Natural History Museum have succeeded in doing what no one else has done before: to isolate newly born little Xenoturbella bocki worms.

“And these new-born worms revealed absolutely no remnants at all of advanced features! Instead, they exhibit similarities with quite simple, ancient animals such as corals and sponges,” says Matthias Obst.

The studies also reveal the value of the University of Gothenburg’s marine stations for important basic research.

“The Lovén Centre at the University of Gothenburg is the only place in the whole world where you can study this paradoxical animal (in Swedish called ‘Paradox worm’). That’s one reason why researchers come from all over the world to Gullmarsfjorden to solve one of the great mysteries in the evolution of animal life,” says Matthias Obst.

Journal Reference:

  1. Hiroaki Nakano, Kennet Lundin, Sarah J. Bourlat, Maximilian J. Telford, Peter Funch, Jens R. Nyengaard, Matthias Obst, Michael C. Thorndyke. Xenoturbella bocki exhibits direct development with similarities to AcoelomorphaNature Communications, 2013; 4: 1537 DOI: 10.1038/ncomms2556

Edward O. Wilson: The Riddle of the Human Species (N.Y.Times)

THE STONEFebruary 24, 2013, 7:30 pm

By EDWARD O. WILSON

The task of understanding humanity is too important and too daunting to leave to the humanities. Their many branches, from philosophy to law to history and the creative arts, have described the particularities of human nature with genius and exquisite detail, back and forth in endless permutations. But they have not explained why we possess our special nature and not some other out of a vast number of conceivable possibilities. In that sense, the humanities have not accounted for a full understanding of our species’ existence.

So, just what are we? The key to the great riddle lies in the circumstance and process that created our species. The human condition is a product of history, not just the six millenniums of civilization but very much further back, across hundreds of millenniums. The whole of it, biological and cultural evolution, in seamless unity, must be explored for an answer to the mystery. When thus viewed across its entire traverse, the history of humanity also becomes the key to learning how and why our species survived.

A majority of people prefer to interpret history as the unfolding of a supernatural design, to whose author we owe obedience. But that comforting interpretation has grown less supportable as knowledge of the real world has expanded. Scientific knowledge (measured by numbers of scientists and scientific journals) in particular has been doubling every 10 to 20 years for over a century. In traditional explanations of the past, religious creation stories have been blended with the humanities to attribute meaning to our species’s existence. It is time to consider what science might give to the humanities and the humanities to science in a common search for a more solidly grounded answer to the great riddle.

To begin, biologists have found that the biological origin of advanced social behavior in humans was similar to that occurring elsewhere in the animal kingdom. Using comparative studies of thousands of animal species, from insects to mammals, they have concluded that the most complex societies have arisen through eusociality — roughly, “true” social condition. The members of a eusocial group cooperatively rear the young across multiple generations. They also divide labor through the surrender by some members of at least some of their personal reproduction in a way that increases the “reproductive success” (lifetime reproduction) of other members.

Leif Parsons

Eusociality stands out as an oddity in a couple of ways. One is its extreme rarity. Out of hundreds of thousands of evolving lines of animals on the land during the past 400 million years, the condition, so far as we can determine, has arisen only about two dozen times. This is likely to be an underestimate, due to sampling error. Nevertheless, we can be certain that the number of originations was very small.

Furthermore, the known eusocial species arose very late in the history of life. It appears to have occurred not at all during the great Paleozoic diversification of insects, 350 to 250 million years before the present, during which the variety of insects approached that of today. Nor is there as yet any evidence of eusocial species during the Mesozoic Era until the appearance of the earliest termites and ants between 200 and 150 million years ago. Humans at the Homo level appeared only very recently, following tens of millions of years of evolution among the primates.

Once attained, advanced social behavior at the eusocial grade has proved a major ecological success. Of the two dozen independent lines, just two within the insects — ants and termites — globally dominate invertebrates on the land. Although they are represented by fewer than 20 thousand of the million known living insect species, ants and termites compose more than half of the world’s insect body weight.

The history of eusociality raises a question: given the enormous advantage it confers, why was this advanced form of social behavior so rare and long delayed? The answer appears to be the special sequence of preliminary evolutionary changes that must occur before the final step to eusociality can be taken. In all of the eusocial species analyzed to date, the final step before eusociality is the construction of a protected nest, from which foraging trips begin and within which the young are raised to maturity. The original nest builders can be a lone female, a mated pair, or a small and weakly organized group. When this final preliminary step is attained, all that is needed to create a eusocial colony is for the parents and offspring to stay at the nest and cooperate in raising additional generations of young. Such primitive assemblages then divide easily into risk-prone foragers and risk-averse parents and nurses.

Leif Parsons

What brought one primate line to the rare level of eusociality? Paleontologists have found that the circumstances were humble. In Africa about two million years ago, one species of the primarily vegetarian australopithecine evidently shifted its diet to include a much higher reliance on meat. For a group to harvest such a high-energy, widely dispersed source of food, it did not pay to roam about as a loosely organized pack of adults and young like present-day chimpanzees and bonobos. It was more efficient to occupy a campsite (thus, the nest) and send out hunters who could bring home meat, either killed or scavenged, to share with others. In exchange, the hunters received protection of the campsite and their own young offspring kept there.

From studies of modern humans, including hunter-gatherers, whose lives tell us so much about human origins, social psychologists have deduced the mental growth that began with hunting and campsites. A premium was placed on personal relationships geared to both competition and cooperation among the members. The process was ceaselessly dynamic and demanding. It far exceeded in intensity anything similar experienced by the roaming, loosely organized bands of most animal societies. It required a memory good enough to assess the intentions of fellow members, to predict their responses, from one moment to the next; and it resulted in the ability to invent and inwardly rehearse competing scenarios of future interactions.

The social intelligence of the campsite-anchored prehumans evolved as a kind of non-stop game of chess. Today, at the terminus of this evolutionary process, our immense memory banks are smoothly activated across the past, present, and future. They allow us to evaluate the prospects and consequences variously of alliances, bonding, sexual contact, rivalries, domination, deception, loyalty and betrayal. We instinctively delight in the telling of countless stories about others as players upon the inner stage. The best of it is expressed in the creative arts, political theory, and other higher-level activities we have come to call the humanities.

The definitive part of the long creation story evidently began with the primitive Homo habilis (or a species closely related to it) two million years ago. Prior to the habilines the prehumans had been animals. Largely vegetarians, they had human-like bodies, but their cranial capacity remained chimpanzee-size, at or below 500 cubic centimeters. Starting with the habiline period the capacity grew precipitously: to 680 cubic centimeters in Homo habilis, 900 in Homo erectus, and about 1,400 in Homo sapiens. The expansion of the human brain was one of the most rapid episodes of evolution of complex organs in the history of life.


Still, to recognize the rare coming together of cooperating primates is not enough to account for the full potential of modern humans that brain capacity provides. Evolutionary biologists have searched for the grandmaster of advanced social evolution, the combination of forces and environmental circumstances that bestowed greater longevity and more successful reproduction on the possession of high social intelligence. At present there are two competing theories of the principal force. The first is kin selection: individuals favor collateral kin (relatives other than offspring) making it easier for altruism to evolve among members of the same group. Altruism in turn engenders complex social organization, and, in the one case that involves big mammals, human-level intelligence.

The second, more recently argued theory (full disclosure: I am one of the modern version’s authors), the grandmaster is multilevel selection. This formulation recognizes two levels at which natural selection operates: individual selection based on competition and cooperation among members of the same group, and group selection, which arises from competition and cooperation between groups. Multilevel selection is gaining in favor among evolutionary biologists because of a recent mathematical proof that kin selection can arise only under special conditions that demonstrably do not exist, and the better fit of multilevel selection to all of the two dozen known animal cases of eusocial evolution.

The roles of both individual and group selection are indelibly stamped (to borrow a phrase from Charles Darwin) upon our social behavior. As expected, we are intensely interested in the minutiae of behavior of those around us. Gossip is a prevailing subject of conversation, everywhere from hunter-gatherer campsites to royal courts. The mind is a kaleidoscopically shifting map of others, each of whom is drawn emotionally in shades of trust, love, hatred, suspicion, admiration, envy and sociability. We are compulsively driven to create and belong to groups, variously nested, overlapping or separate, and large or small. Almost all groups compete with those of similar kind in some manner or other. We tend to think of our own as superior, and we find our identity within them.

The existence of competition and conflict, the latter often violent, has been a hallmark of societies as far back as archaeological evidence is able to offer. These and other traits we call human nature are so deeply resident in our emotions and habits of thought as to seem just part of some greater nature, like the air we all breathe, and the molecular machinery that drives all of life. But they are not. Instead, they are among the idiosyncratic hereditary traits that define our species.

The major features of the biological origins of our species are coming into focus, and with this clarification the potential of a more fruitful contact between science and the humanities. The convergence between these two great branches of learning will matter hugely when enough people have thought it through. On the science side, genetics, the brain sciences, evolutionary biology, and paleontology will be seen in a different light. Students will be taught prehistory as well as conventional history, the whole presented as the living world’s greatest epic.

We will also, I believe, take a more serious look at our place in nature. Exalted we are indeed, risen to be the mind of the biosphere without a doubt, our spirits capable of awe and ever more breathtaking leaps of imagination. But we are still part of earth’s fauna and flora. We are bound to it by emotion, physiology, and not least, deep history. It is dangerous to think of this planet as a way station to a better world, or continue to convert it into a literal, human-engineered spaceship. Contrary to general opinion, demons and gods do not vie for our allegiance. We are self-made, independent, alone and fragile. Self-understanding is what counts for long-term survival, both for individuals and for the species.

Edward O. Wilson is Honorary Curator in Entomology and University Research Professor Emeritus, Harvard University. He has received more than 100 awards for his research and writing, including the U. S. National Medal of Science, the Crafoord Prize and two Pulitzer Prizes in non-fiction. His most recent book is “The Social Conquest of Earth.”

*   *   *

Interview with Edward O. Wilson: The Origin of Morals (Spiegel)

February 26, 2013 – 01:23 PM

By Philip Bethge and Johann Grolle

American sociobiologist Edward O. Wilson is championing a controversial new approach for explaining the origins of virtue and sin. In an interview, the world-famous ant reseacher explains why he believes the inner struggle is the characteristic trait of human nature.

Edward O. Wilson doesn’t come across as the kind of man who’s looking to pick a fight. With his shoulders upright and his head tilting slightly to the side, he shuffles through the halls of Harvard University. His right eye, which has given him trouble since his childhood, is halfway closed. The other is fixed on the ground. As an ant researcher, Wilson has made a career out of things that live on the earth’s surface.

There’s also much more to Wilson. Some consider him to be the world’s most important living biologist, with some placing him on a level with Charles Darwin.

In addition to discovering and describing hundreds of species of ants, Wilson’s book on this incomparably successful group of insects is the only non-fiction biology tome ever to win a Pulitzer Prize. Another achievement was decoding the chemical communication of ants, whose vocabulary is composed of pheromones. His study of the ant colonization of islands helped to establish one of the most fruitful branches of ecology. And when it comes to the battle against the loss of biodiversity, Wilson is one of the movement’s most eloquent voices.

‘Blessed with Brilliant Enemies’

But Wilson’s fame isn’t solely the product of his scientific achievements. His enemies have also helped him to establish a name. “I have been blessed with brilliant enemies,” he says. In fact, the multitude of scholars with whom Wilson has skirmished academically is illustrious. James Watson, one of the discoverers of the double helix in DNA is among them, as is essayist Stephen Jay Gould.

At 83 years of age, Wilson is still at work making a few new enemies. The latest source of uproar is a book, “The Social Conquest of Earth,” published last April in the United States and this month in a German-language edition. In the tome, Wilson attempts to describe the triumphal advance of humans in evolutionary terms.

It is not uncommon for Wilson to look to ants for inspiration in his writings — and that proves true here, as well. When, for example, he recalls beholding two 90-million-year-old worker ants that were trapped in a piece of fossil metasequoia amber as being “among the most exciting moments in my life,” a discovery that “ranked in scientific importance withArchaeopteryx, the first fossil intermediary between birds and dinosaurs, and Australopithecus, the first ‘missing link’ discovered between modern humans and the ancestral apes.”

But that’s all just foreplay to the real controversy at the book’s core. Ultimately, Wilson uses ants to explain humans’ social behavior and, by doing so, breaks with current convention. The key question is the level at which Darwinian selection of human characteristics takes place. Did individuals enter into a fight for survival against each other, or did groups battle it out against competing groups?

Prior to this book, Wilson had been an influential champion of the theory of kin selection. He has now rejected his previous teachings, literally demolishing them. “The beautiful theory never worked well anyway, and now it has collapsed,” he writes. Today, he argues that human nature can only be understood if it is perceived as being the product of “group selection” — a view that Wilson’s fellow academics equate with sacrilege. They literally lined up to express their scientific dissent in a joint letter.

Some of the most vociferous criticism has come from Richard Dawkins, whose bestselling 1976 book “The Selfish Gene” first introduced the theory of kin selection to a mass audience. In a withering review of Wilson’s book in Britain’s Prospect magazine, Dawkins accuses a man he describes as his “lifelong hero” of “wanton arrogance” and “perverse misunderstandings”. “To borrow from Dorothy Parker,” he writes, “this is not a book to be tossed lightly aside. It should be thrown with great force.”

SPIEGEL recently sat down with sociobiologist Wilson to discuss his book and the controversy surrounding it.

SPIEGEL: Professor Wilson, lets assume that 10 million years ago some alien spacecraft had landed on this planet. Which organisms would they find particularly intriguing?

Wilson: Their interest, I believe, would not have been our ancestors. Primarily, they would have focused on ants, bees, wasps, and termites. Their discovery is what the aliens would report back to headquarters.

SPIEGEL: And you think those insects would be more interesting to them than, for example, elephants, flocks of birds or intelligent primates?

Wilson: They would be, because, at that time, ants and termites would be the most abundant creatures on the land and the most highly social creatures with very advanced division of labor and caste. We call them “eusocial,” and this phenomenon seems to be extremely rare.

SPIEGEL: What else might the aliens consider particularly interesting about ants?

Wilson: Ants engage in farming and animal husbandry. For example, some of them cultivate fungi. Others herd aphids and literally milk them by stroking them with their antennae. And the other thing the aliens would find extremely interesting would be the degree to which these insects organize their societies by pheromones, by chemical communication. Ants and termites have taken this form of communication to extremes.

SPIEGEL: So the aliens would cable back home: “We have found ants. They are the most promising candidates for a future evolution towards intelligent beings on earth?”

Wilson: No, they wouldn’t. They would see that these creatures were encased in exoskeletons and therefore had to remain very small. They would conclude that there was little chance for individual ants or termites to develop much reasoning power, nor, as a result, the capacity for culture. But at least on this planet, you have to be big in order to have sufficient cerebral cortex. And you probably have to be bipedal and develop hands with pulpy fingers, because those give you the capacity to start creating objects and to manipulate the environment.

SPIEGEL: Would our ancestors not have caught their eye?

Wilson: Ten million years ago, our ancestors indeed had developed a somewhat larger brain and versatile hands already. But the crucial step had yet to come.

SPIEGEL: What do you mean?

Wilson: Let me go back to the social insects for a moment. Why did social insects start to form colonies? Across hundreds of millions of years, insects had been proliferating as solitary forms. Some of them stayed with their young for a while, guided them and protected them. You find that widespread but far from universal in the animal kingdom. However, out of those species came a much smaller number of species who didn’t just protect their young, but started building nests that they defended …

SPIEGEL: … similar to birds.

Wilson: Yes. And I think that birds are right at the threshold of eusocial behaviour. But looking at the evolution of ants and termites again, there is another crucial step. In an even smaller group, the young don’t only grow up in their nest, but they also stay and care for the next generation. Now you have a group staying together with a division of labor. That is evidently the narrow channel of evolution that you have to pass through in order to become eusocial.

SPIEGEL: And our ancestors followed the same path?

Wilson: Yes. I argue that Homo habilis, the first humans, also went through these stages. In particular, Homo habilis was unique in that they already had shifted to eating meat.

SPIEGEL: What difference would that make?

Wilson: When animals start eating meat, they tend to form packs and to divide labor. We know that the immediate descendants of Homo habilis, Homo erectus, gathered around camp sites and that they actually had begun to use fire. These camp sites are equivalent to nests. That’s where they gathered in a tightly knit group, and then individuals went out searching for food.

SPIEGEL: And this development of groups drives evolution even further?

Wilson: Exactly. And, for example, if it now comes to staking out the hunting grounds, then group stands against group.

SPIEGEL: Meaning that this is the origin of warfare?

Wilson: Yes. But it doesn’t take necessarily the forming of an army or a battalion and meeting on the field and fighting. It was mostly what you call “vengeance raids”. One group attacks another, maybe captures a female or kills one or two males. The other group then counterraids, and this will go back and forth, group against group.

SPIEGEL: You say that this so called group selection is vital for the evolution of humans. Yet traditionally, scientists explain the emergence of social behavior in humans by kin selection.

Wilson: That, for a number of reasons, isn’t much good as an explanation.

SPIEGEL: But you yourself have long been a proponent of this theory. Why did you change your mind?

Wilson: You are right. During the 1970s, I was one of the main proponents of kin selection theory. And at first the idea sounds very reasonable. So for example, if I favored you because you were my brother and therefore we share one half of our genes, then I could sacrifice a lot for you. I could give up my chance to have children in order to get you through college and have a big family. The problem is: If you think it through, kin selection doesn’t explain anything. Instead, I came to the conclusion that selection operates on multiple levels. On one hand, you have normal Darwinian selection going on all the time, where individuals compete with each other. In addition, however, these individuals now form groups. They are staying together, and consequently it is group versus group.

SPIEGEL: Turning away from kin selection provoked a rather fierce reaction from many of your colleagues.

Wilson: No, it didn’t. The reaction was strong, but it came from a relatively small group of people whose careers are based upon studies of kin selection.

SPIEGEL: Isn’t that too easy? After all, 137 scientists signed a response to your claims. They accuse you of a “misunderstanding of evolutionary theory”.

Wilson: You know, most scientists are tribalists. Their lives are so tied up in certain theories that they can’t let go.

SPIEGEL: Does it even make a substantial difference if humans evolved through kin selection or group selection?

Wilson: Oh, it changes everything. Only the understanding of evolution offers a chance to get a real understanding of the human species. We are determined by the interplay between individual and group selection where individual selection is responsible for much of what we call sin, while group selection is responsible for the greater part of virtue. We’re all in constant conflict between self-sacrifice for the group on the one hand and egoism and selfishness on the other. I go so far as to say that all the subjects of humanities, from law to the creative arts are based upon this play of individual versus group selection.

SPIEGEL: Is this Janus-faced nature of humans our greatest strength at the end of the day?

Wilson: Exactly. This inner conflict between altruism and selfishness is the human condition. And it is very creative and probably the source of our striving, our inventiveness and imagination. It’s that eternal conflict that makes us unique.

SPIEGEL: So how do we negotiate this conflict?

Wilson: We don’t. We have to live with it.

SPIEGEL: Which element of this human condition is stronger?

Wilson: Let’s put it this way: If we would be mainly influenced by group selection, we would be living in kind of an ant society.

SPIEGEL: … the ultimate form of communism?

Wilson: Yes. Once in a while, humans form societies that emphasize the group, for example societies with Marxist ideology. But the opposite is also true. In other societies the individual is everything. Politically, that would be the Republican far right.

SPIEGEL: What determines which ideology is predominant in a society?

Wilson: If your territory is invaded, then cooperation within the group will be extreme. That’s a human instinct. If you are in a frontier area, however, then we tend to move towards the extreme individual level. That seems to be a good part of the problem still with America. We still think we’re on the frontier, so we constantly try to put forward individual initiative and individual rights and rewards based upon individual achievement.

SPIEGEL: Earlier, you differentiated between the “virtue” of altruism and the “sin” of individualism. In your book you talk about the “poorer and the better angels” of human nature. Is it helpful to use this kind of terminology?

Wilson: I will admit that using the terminology of “virtue” and “sin” is what poets call a “trope”. That is to say, I wanted the idea in crude form to take hold. Still, a lot of what we call “virtue” has to do with propensities to behave well toward others. What we call “sin” are things that people do mainly out of self-interest.

SPIEGEL: However, our virtues towards others go only so far. Outside groups are mainly greeted with hostility.

Wilson: You are right. People have to belong to a group. That’s one of the strongest propensities in the human psyche and you won’t be able to change that. However, I think we are evolving, so as to avoid war — but without giving up the joy of competition between groups. Take soccer …

SPIEGEL: … or American football.

Wilson: Oh, yes, American football, it’s a blood sport. And people live by team sports and national or regional pride connected with team sports. And that’s what we should be aiming for, because, again, that spirit is one of the most creative. It landed us on the moon, and people get so much pleasure from it. I don’t want to see any of that disturbed. That is a part of being human. We need our big games, our team sports, our competition, our Olympics.

SPIEGEL: “Humans,” the saying goes, “have Paleolithic emotions” …

Wilson: … “Medieval institutions and god-like technology”. That’s our situation, yeah. And we really have to handle that.

SPIEGEL: How?

Wilson: So often it happens that we don’t know how, also in situations of public policy and governance, because we don’t have enough understanding of human nature. We simply haven’t looked at human nature in the best way that science might provide. I think what we need is a new Enlightenment. During the 18th century, when the original Enlightenment took place, science wasn’t up to the job. But I think science is now up to the job. We need to be harnessing our scientific knowledge now to get a better, science-based self-understanding.

SPIEGEL: It seems that, in this process, you would like to throw religions overboard altogether?

Wilson: No. That’s a misunderstanding. I don’t want to see the Catholic Church with all of its magnificent art and rituals and music disappear. I just want to have them give up their creation stories, including especially the resurrection of Christ.

SPIEGEL: That might well be a futile endeavour …

Wilson: There was this American physiologist who was asked if Mary’s bodily ascent from Earth to Heaven was possible. He said, “I wasn’t there; therefore, I’m not positive that it happened or didn’t happen; but of one thing I’m certain: She passed out at 10,000 meters.” That’s where science comes in. Seriously, I think we’re better off with no creation stories.

SPIEGEL: With this new Enlightenment, will we reach a higher state of humanity?

Wilson: Do we really want to improve ourselves? Humans are a very young species, in geologic terms, and that’s probably why we’re such a mess. We’re still living with all this aggression and ability to go to war. But do we really want to change ourselves? We’re right on the edge of an era of being able to actually alter the human genome. But do we want that? Do we want to create a race that’s more rational and free of many of these emotions? My response is no, because the only thing that distinguishes us from super-intelligent robots are our imperfect, sloppy, maybe even dangerous emotions. They are what makes us human.

SPIEGEL: Mr. Wilson, we thank you for this conversation.

Interview conducted by Philip Bethge and Johann Grolle

Far from random, evolution follows a predictable genetic pattern, Princeton researchers find (Princeton)

Posted October 25, 2012; 12:00 p.m.

by Morgan Kelly, Office of Communications

Evolution, often perceived as a series of random changes, might in fact be driven by a simple and repeated genetic solution to an environmental pressure that a broad range of species happen to share, according to new research.

Princeton University research published in the journal Science suggests that knowledge of a species’ genes — and how certain external conditions affect the proteins encoded by those genes — could be used to determine a predictable evolutionary pattern driven by outside factors. Scientists could then pinpoint how the diversity of adaptations seen in the natural world developed even in distantly related animals.

Andolfatto bug

The Princeton researchers sequenced the expression of a poison-resistant protein in insect species that feed on plants such as milkweed and dogbane that produce a class of steroid-like cardiotoxins called cardenolides as a natural defense. The insects surveyed spanned three orders: butterflies and moths (Lepidoptera); beetles and weevils (Coleoptera); and aphids, bed bugs, milkweed bugs and other sucking insects (Hemiptera). Above: Dogbane beetle(Photo courtesy of Peter Andolfatto)

“Is evolution predictable? To a surprising extent the answer is yes,” said senior researcher Peter Andolfatto, an assistant professor in Princeton’s Department of Ecology and Evolutionary Biology and the Lewis-Sigler Institute for Integrative Genomics. He worked with lead author and postdoctoral research associate Ying Zhen, and graduate students Matthew Aardema and Molly Schumer, all from Princeton’s ecology and evolutionary biology department, as well as Edgar Medina, a biological sciences graduate student at the University of the Andes in Colombia.

The researchers carried out a survey of DNA sequences from 29 distantly related insect species, the largest sample of organisms yet examined for a single evolutionary trait. Fourteen of these species have evolved a nearly identical characteristic due to one external influence — they feed on plants that produce cardenolides, a class of steroid-like cardiotoxins that are a natural defense for plants such as milkweed and dogbane.

Though separated by 300 million years of evolution, these diverse insects — which include beetles, butterflies and aphids — experienced changes to a key protein called sodium-potassium adenosine triphosphatase, or the sodium-potassium pump, which regulates a cell’s crucial sodium-to-potassium ratio. The protein in these insects eventually evolved a resistance to cardenolides, which usually cripple the protein’s ability to “pump” potassium into cells and excess sodium out.

Andolfatto lab

Lead author Ying Zhen (foreground), Andolfatto (far left), fourth author and graduate student Molly Schumer (near left), and their co-authors sequenced and assembled all the expressed genes in 29 distantly related insect species, the largest sample of organisms yet examined for a single evolutionary trait. They used these sequences to predict how a certain protein would be encoded in the genes of 14 distantly related species that evolved a similar resistance to toxic plants. Similar techniques could be used to trace protein changes in a species’ DNA to understand how many diverse organisms evolved as a result of environmental factors. At right is research assistant Ilona Ruhl, who was not involved in the research. (Photo by Denise Applewhite)

Andolfatto and his co-authors first sequenced and assembled all the expressed genes in the studied species. They used these sequences to predict how the sodium-potassium pump would be encoded in each of the species’ genes based on cardenolide exposure.

Scientists using similar techniques could trace protein changes in a species’ DNA to understand how many diverse organisms evolved as a result of environmental factors, Andolfatto said. “To apply this approach more generally a scientist would have to know something about the genetic underpinnings of a trait and investigate how that trait evolves in large groups of species facing a common evolutionary problem,” Andolfatto said.

“For instance, the sodium-potassium pump also is a candidate gene location related to salinity tolerance,” he said. “Looking at changes to this protein in the right organisms could reveal how organisms have or may respond to the increasing salinization of oceans and freshwater habitats.”

Andolfatto bug

Milkweed tussock moth (Photo courtesy of Peter Andolfatto)

Jianzhi Zhang, a University of Michigan professor of ecology and evolutionary biology, said that the Princeton-based study shows that certain traits have a limited number of molecular mechanisms, and that numerous, distinct species can share the few mechanisms there are. As a result, it is likely that a cross-section of certain organisms can provide insight into the development of other creatures, he said.

“The finding of parallel evolution in not two, but numerous herbivorous insects increases the significance of the study because such frequent parallelism is extremely unlikely to have happened simply by chance,” said Zhang, who is familiar with the study but had no role in it.

“It shows that a common molecular mechanism is used by many different insects to defend themselves against the toxins in their food, suggesting that perhaps the number of potential mechanisms for achieving this goal is very limited,” he said. “That many different insects independently evolved the same molecular tricks to defend themselves against the same toxin suggests that studying a small number of well-chosen model organisms can teach us a lot about other species. Yes, evolution is predictable to a certain degree.”

Andolfatto and his co-authors examined the sodium-potassium pump protein because of its well-known sensitivity to cardenolides. In order to function properly in a wide variety of physiological contexts, cells must be able to control levels of potassium and sodium. Situated on the cell membrane, the protein generates a desired potassium to sodium ratio by “pumping” three sodium atoms out of the cell for every two potassium atoms it brings in.

Cardenolides disrupt the exchange of potassium and sodium, essentially shutting down the protein, Andolfatto said. The human genome contains four copies of the pump protein, and it is a candidate gene for a number of human genetic disorders, including salt-sensitive hypertension and migraines. In addition, humans have long used low doses of cardenolides medicinally for purposes such as controlling heart arrhythmia and congestive heart failure.

Andolfatto bug

Large milkweed bugs (Photo courtesy of Peter Andolfatto)

The Princeton researchers used the DNA microarray facility in the University’s Lewis-Sigler Institute for Integrative Genomics to sequence the expression of the sodium-potassium pump protein in insect species spanning three orders: butterflies and moths (Lepidoptera); beetles and weevils (Coleoptera); and aphids, bed bugs, milkweed bugs and other sucking insects (Hemiptera).

The researchers found that the genes of cardenolide-resistant insects incorporated various mutations that allowed it to resist the toxin. During the evolutionary timeframe examined, the sodium-potassium pump of insects feeding on dogbane and milkweed underwent 33 mutations at sites known to affect sensitivity to cardenolides. These mutations often involved similar or identical amino-acid changes that reduced susceptibility to the toxin. On the other hand, the sodium-potassium pump mutated just once in insects that do not feed on these plants.

Significantly, the researchers found that multiple gene duplications occurred in the ancestors of several of the resistant species. These insects essentially wound up with one conventional sodium-potassium pump protein and one “experimental” version, Andolfatto said. In these insects, the newer, hardier versions of the sodium-potassium pump are mostly expressed in gut tissue where they are likely needed most.

“These gene duplications are an elegant solution to the problem of adapting to environmental changes,” Andolfatto said. “In species with these duplicates, the organism is free to experiment with one copy while keeping the other constant, avoiding the risk that the new version of the protein will not perform its primary job as well.”

The researchers’ findings unify the generally separate ideas of what predominately drives genetic evolution: protein evolution, the evolution of the elements that control protein expression or gene duplication. This study shows that all three mechanisms can be used to solve the same evolutionary problem, Andolfatto said.

Central to the work is the breadth of species the researchers were able to examine using modern gene sequencing equipment, Andolfatto said.

“Historically, studying genetic evolution at this level has been conducted on just a handful of ‘model’ organisms such as fruit flies,” Andolfatto said. “Modern sequencing methods allowed us to approach evolutionary questions in a different way and come up with more comprehensive answers than had we examined one trait in any one organism.

“The power of what we’ve done is to survey diverse organisms facing a similar problem and find striking evidence for a limited number of possible solutions,” he said. “The fact that many of these solutions are used over and over again by completely unrelated species suggests that the evolutionary path is repeatable and predictable.”

The paper, “Parallel Molecular Evolution in an Herbivore Community,” was published Sept. 28 by Science. The research was supported by grants from the Centre for Genetic Engineering and Biotechnology, the National Science Foundation and the National Institutes of Health.

Developmental biologist proposes new theory of early animal evolution (New York Medical College)

Alternative model challenges a basic assumption of evolution

Public release date: 11-Oct-2012
By Donna E. Moriarty, MPH
New York Medical College

VALHALLA, October 11, 2012—A New York Medical College developmental biologist whose life’s work has supported the theory of evolution has developed a concept that dramatically alters one of its basic assumptions—that survival is based on a change’s functional advantage if it is to persist. Stuart A. Newman, Ph.D., professor of cell biology and anatomy, offers an alternative model in proposing that the origination of the structural motifs of animal form were actually predictable and relatively sudden, with abrupt morphological transformations favored during the early period of animal evolution.

Newman’s long view of evolution is fully explained in his perspective article, “Physico-Genetic Determinants in the Evolution of Development,” which is to be published in the October 12 issue of the journal Science, in a special section called Forces in Development. The paper has been selected for early online publication and a podcast interview with the scientist*.

Evolution is commonly thought to take place opportunistically, by small steps, with each change persisting, or not, based on its functional advantage. Newman’s alternative model is based on recent inferences about the genetics of the single-celled ancestors of the animals and, more surprisingly, the physics of “middle-scale” materials.

Animal bodies and the embryos that generate them exhibit an assortment of recurrent “morphological motifs” which, on the evidence of the fossil record, first appeared more than a half billion years ago. During embryonic development of present-day animals, cells arrange themselves into tissues having non-mixing layers and interior cavities. Embryos contain patterned arrangements of cell types with which they may form segments, exoskeletons and blood vessels. Developing bodies go on to fold, elongate, and extend appendages, and in some species, generate endoskeletons with repeating elements (e.g., the human hand).

These developmental motifs are strikingly similar to the forms assumed by nonliving condensed, chemically active, viscoelastic materials when they are organized by relevant physical forces and effects, although the mechanisms that generate the motifs in living embryos are typically much more complex. Newman proposes that the ancestors of the present-day animals acquired these forms when ancient single-celled organisms came to reside in multicellular clusters and physical processes relevant to matter at this new (for cellular life) spatial scale were immediately mobilized.

The unicellular progenitors are believed to have contained genes of the “developmental-genetic toolkit” with which all present-day animals orchestrate embryonic development, though they used the genes for single-cell functions. It was precisely these genes whose products enabled the ancestral clusters to harness the middle-scale physical effects that produced the characteristic motifs. And since not every ancestral cluster contained the same selection of toolkit genes, different body forms arose in parallel, giving rise to the modern morphologically distinct animal phyla.

Natural selection, acting over the hundreds of millions of years since the occurrence of these origination events led, according to Newman’s hypothesis, to more complex developmental processes which have made embryogenesis much less dependent on potentially inconsistent physical determinants, although the “physical” motifs were retained. As Newman describes in his article, this new perspective provides natural interpretations for puzzling aspects of the early evolution of the animals, including the “explosive” rise of complex body forms between 540 and 640 million years ago and the failure to add new motifs since that time. The model also helps us to understand the conserved use of the same set of genes to orchestrate development in all of the morphologically diverse phyla, and the “embryonic hourglass” of comparative developmental biology: the observation that the species of a phylum can have drastically different trajectories of early embryogenesis (e.g., frogs and mice), but still wind up with very similar “body plans.”

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This link will take you to the podcast segment featuring the interview with Dr. Newman: http://www.sciencemag.org/content/338/6104/217/suppl/DC1

The eyes have it: Men do see things differently to women (BioMed Central)

By Hilary Glover

BioMed Central

The way that the visual centers of men and women’s brains works is different, finds new research published in BioMed Central’s open access journal Biology of Sex Differences. Men have greater sensitivity to fine detail and rapidly moving stimuli, but women are better at discriminating between colors.

In the brain there are high concentrations of male sex hormone (androgen) receptors throughout cerebral cortex, especially in the visual cortex which is responsible for processing images. Androgens are also responsible for controlling the development of neurons in the visual cortex during embryogenesis, meaning that males have 25% more of these neurons than females.

Researchers from Brooklyn and Hunter Colleges of the City University of New York compared the vision of men and women aged over 16 from both college and high school, including students and staff. All volunteers were required to have normal color vision and 20/20 sight (or 20/20 when corrected by glasses or contact lenses).

When the volunteers were required to describe colors shown to them across the visual spectrum it became obvious that the color vision of men was shifted, and that they required a slightly longer wavelength to experience the same hue as the women. The males also had a broader range in the center of the spectrum where they were less able to discriminate between colors.

An image of light and dark bars was used to measure contrast-sensitivity functions (CSF) of vision; the bars were either horizontal or vertical and volunteers had to choose which one they saw. In each image, when the light and dark bars were alternated the image appeared to flicker.

By varying how rapidly the bars alternated or how close together they were, the team found that at moderate rates of image change, observers lost sensitivity for close together bars, and gained sensitivity when the bars were farther apart. However when the image change was faster both sexes were less able to resolve the images over all bar widths. Overall the men were better able to resolve more rapidly changing images that were closer together than the women.

Prof Israel Abramov, who led this study commented, “As with other senses, such as hearing and the olfactory system, there are marked sex differences in vision between men and women. The elements of vision we measured are determined by inputs from specific sets of thalamic neurons into the primary visual cortex. We suggest that, since these neurons are guided by the cortex during embryogenesis, that testosterone plays a major role, somehow leading to different connectivity between males and females. The evolutionary driving force between these differences is less clear.”

Sources

Sex & vision I: Spatio-temporal resolution Israel Abramov, James Gordon, Olga Feldman and Alla Chavarga Biology of Sex Differences (in press)

Sex and vision II: Color appearance of monochromatic lights Israel Abramov, James Gordon, Olga Feldman and Alla Chavarga Biology of Sex Differences (in press)

Populations Survive Despite Many Deleterious Mutations: Evolutionary Model of Muller’s Ratchet Explored (Science Daily)

ScienceDaily (Aug. 10, 2012) — From protozoans to mammals, evolution has created more and more complex structures and better-adapted organisms. This is all the more astonishing as most genetic mutations are deleterious. Especially in small asexual populations that do not recombine their genes, unfavourable mutations can accumulate. This process is known as Muller’s ratchet in evolutionary biology. The ratchet, proposed by the American geneticist Hermann Joseph Muller, predicts that the genome deteriorates irreversibly, leaving populations on a one-way street to extinction.

Equilibrium of mutation and selection processes: A population can be divided into groups of individuals that carry different numbers of deleterious mutations. Groups with few mutations are amplified by selection but loose members to other groups by mutation. Groups with many mutations don’t reproduce as much, but gain members by mutation. (Credit: © Richard Neher/MPI for Developmental Biology)

In collaboration with colleagues from the US, Richard Neher from the Max Planck Institute for Developmental Biology has shown mathematically how Muller’s ratchet operates and he has investigated why populations are not inevitably doomed to extinction despite the continuous influx of deleterious mutations.

The great majority of mutations are deleterious. “Due to selection individuals with more favourable genes reproduce more successfully and deleterious mutations disappear again,” explains the population geneticist Richard Neher, leader of an independent Max Planck research group at the Max Planck Institute for Developmental Biology in Tübingen, Germany. However, in small populations such as an asexually reproducing virus early during infection, the situation is not so clear-cut. “It can then happen by chance, by stochastic processes alone, that deleterious mutations in the viruses accumulate and the mutation-free group of individuals goes extinct,” says Richard Neher. This is known as a click of Muller’s ratchet, which is irreversible — at least in Muller’s model.

Muller published his model on the evolutionary significance of deleterious mutations in 1964. Yet to date a quantitative understanding of the ratchet’s processes was lacking. Richard Neher and Boris Shraiman from the University of California in Santa Barbara have now published a new theoretical study on Muller’s ratchet. They chose a comparably simple model with only deleterious mutations all having the same effect on fitness. The scientists assumed selection against those mutations and analysed how fluctuations in the group of the fittest individuals affected the less fit ones and the whole population. Richard Neher and Boris Shraiman discovered that the key to the understanding of Muller’s ratchet lies in a slow response: If the number of the fittest individuals is reduced, the mean fitness decreases only after a delay. “This delayed feedback accelerates Muller’s ratchet,” Richard Neher comments on the results. It clicks more and more frequently.

“Our results are valid for a broad range of conditions and parameter values — for a population of viruses as well as a population of tigers.” However, he does not expect to find the model’s conditions one-to-one in nature. “Models are made to understand the essential aspects, to identify the critical processes,” he explains.

In a second study Richard Neher, Boris Shraiman and several other US-scientists from the University of California in Santa Barbara and Harvard University in Cambridge investigated how a small asexual population could escape Muller’s ratchet. “Such a population can only stay in a steady state for a long time when beneficial mutations continually compensate for the negative ones that accumulate via Muller’s ratchet,” says Richard Neher. For their model the scientists assumed a steady environment and suggest that there can be a mutation-selection balance in every population. They have calculated the rate of favourable mutations required to maintain the balance. The result was surprising: Even under unfavourable conditions, a comparably small proportion in the range of several percent of positive mutations is sufficient to sustain a population.

These findings could explain the long-term maintenance of mitochondria, the so-called power plants of the cell that have their own genome and divide asexually. By and large, evolution is driven by random events or as Richard Neher says: “Evolutionary dynamics are very stochastic.”

Why Do Organisms Build Tissues They Seemingly Never Use? (Science Daily)

ScienceDaily (Aug. 10, 2012) — Why, after millions of years of evolution, do organisms build structures that seemingly serve no purpose?

A study conducted at Michigan State University and published in the current issue of The American Naturalist investigates the evolutionary reasons why organisms go through developmental stages that appear unnecessary.

“Many animals build tissues and structures they don’t appear to use, and then they disappear,” said Jeff Clune, lead author and former doctoral student at MSU’s BEACON Center of Evolution in Action. “It’s comparable to building a roller coaster, razing it and building a skyscraper on the same ground. Why not just skip ahead to building the skyscraper?”

Why humans and other organisms retain seemingly unnecessary stages in their development has been debated between biologists since 1866. This study explains that organisms jump through these extra hoops to avoid disrupting a developmental process that works. Clune’s team called this concept the “developmental disruption force.” But Clune says it also could be described as “if the shoe fits, don’t change a thing.”

“In a developing embryo, each new structure is built in a delicate environment that consists of everything that has already developed,” said Clune, who is now a postdoctoral fellow at Cornell University. “Mutations that alter that environment, such as by eliminating a structure, can thus disrupt later stages of development. Even if a structure is not actually used, it may set the stage for other functional tissues to grow properly.”

Going back to the roller coaster metaphor, even though the roller coaster gets torn down, the organism needs the parts from that teardown to build the skyscraper, he added.

“An engineer would simply skip the roller coaster step, but evolution is more of a tinkerer and less of an engineer,” Clune said. “It uses whatever parts that are lying around, even if the process that generates those parts is inefficient.”

An interesting consequence is that newly evolved traits tend to get added at the end of development, because there is less risk of disrupting anything important. That, in turn, means that there is a similarity between the order things evolve and the order they develop.

A new technology called computational evolution allowed the team to conduct experiments that would be impossible to reproduce in nature.

Rather than observe embryos grow, the team of computer scientists and biologists used BEACON’s Avida software to perform experiments with evolution inside a computer. The Avidians — self-replicating computer programs — mutate, compete for resources and evolve, mimicking natural selection in real-life organisms. Using this software, Clune’s team observed as Avidians evolved to perform logic tasks. They recorded the order that those tasks evolved in a variety of lineages, and then looked at the order those tasks developed in the final, evolved organism.

They were able to help settle an age-old debate that developmental order does resemble evolutionary order, at least in this computationally evolving system. Because in a computer thousands of generations can happen overnight, the team was able to repeat this experiment many times to document that this similarity repeatedly occurs.

Additional MSU researchers contributing to the study included BEACON colleagues Richard Lenski, Robert Pennock and Charles Ofria. The research was funded by the National Science Foundation.

Why Are Elderly Duped? Area in Brain Where Doubt Arises Changes With Age (Science Daily)

ScienceDaily (Aug. 16, 2012) — Everyone knows the adage: “If something sounds too good to be true, then it probably is.” Why, then, do some people fall for scams and why are older folks especially prone to being duped?

An answer, it seems, is because a specific area of the brain has deteriorated or is damaged, according to researchers at the University of Iowa. By examining patients with various forms of brain damage, the researchers report they’ve pinpointed the precise location in the human brain, called the ventromedial prefrontal cortex, that controls belief and doubt, and which explains why some of us are more gullible than others.

“The current study provides the first direct evidence beyond anecdotal reports that damage to the vmPFC (ventromedial prefrontal cortex) increases credulity. Indeed, this specific deficit may explain why highly intelligent vmPFC patients can fall victim to seemingly obvious fraud schemes,” the researchers wrote in the paper published in a special issue of the journal Frontiers in Neuroscience.

A study conducted for the National Institute of Justice in 2009 concluded that nearly 12 percent of Americans 60 and older had been exploited financially by a family member or a stranger. And, a report last year by insurer MetLife Inc. estimated the annual loss by victims of elder financial abuse at $2.9 billion.

The authors point out their research can explain why the elderly are vulnerable.

“In our theory, the more effortful process of disbelief (to items initially believed) is mediated by the vmPFC, which, in old age, tends to disproportionately lose structural integrity and associated functionality,” they wrote. “Thus, we suggest that vulnerability to misleading information, outright deception and fraud in older adults is the specific result of a deficit in the doubt process that is mediated by the vmPFC.”

The ventromedial prefrontal cortex is an oval-shaped lobe about the size of a softball lodged in the front of the human head, right above the eyes. It’s part of a larger area known to scientists since the extraordinary case of Phineas Gage that controls a range of emotions and behaviors, from impulsivity to poor planning. But brain scientists have struggled to identify which regions of the prefrontal cortex govern specific emotions and behaviors, including the cognitive seesaw between belief and doubt.

The UI team drew from its Neurological Patient Registry, which was established in 1982 and has more than 500 active members with various forms of damage to one or more regions in the brain. From that pool, the researchers chose 18 patients with damage to the ventromedial prefrontal cortex and 21 patients with damage outside the prefrontal cortex. Those patients, along with people with no brain damage, were shown advertisements mimicking ones flagged as misleading by the Federal Trade Commission to test how much they believed or doubted the ads. The deception in the ads was subtle; for example, an ad for “Legacy Luggage” that trumpets the gear as “American Quality” turned on the consumer’s ability to distinguish whether the luggage was manufactured in the United States versus inspected in the country.

Each participant was asked to gauge how much he or she believed the deceptive ad and how likely he or she would buy the item if it were available. The researchers found that the patients with damage to the ventromedial prefrontal cortex were roughly twice as likely to believe a given ad, even when given disclaimer information pointing out it was misleading. And, they were more likely to buy the item, regardless of whether misleading information had been corrected.

“Behaviorally, they fail the test to the greatest extent,” says Natalie Denburg, assistant professor in neurology who devised the ad tests. “They believe the ads the most, and they demonstrate the highest purchase intention. Taken together, it makes them the most vulnerable to being deceived.” She added the sample size is small and further studies are warranted.

Apart from being damaged, the ventromedial prefrontal cortex begins to deteriorate as people reach age 60 and older, although the onset and the pace of deterioration varies, says Daniel Tranel, neurology and psychology professor at the UI and corresponding author on the paper. He thinks the finding will enable doctors, caregivers, and relatives to be more understanding of decision making by the elderly.

“And maybe protective,” Tranel adds. “Instead of saying, ‘How would you do something silly and transparently stupid,’ people may have a better appreciation of the fact that older people have lost the biological mechanism that allows them to see the disadvantageous nature of their decisions.”

The finding corroborates an idea studied by the paper’s first author, Erik Asp, who wondered why damage to the prefrontal cortex would impair the ability to doubt but not the initial belief as well. Asp created a model, which he called the False Tagging Theory, to separate the two notions and confirm that doubt is housed in the prefrontal cortex.

“This study is strong empirical evidence suggesting that the False Tagging Theory is correct,” says Asp, who earned his doctorate in neuroscience from the UI in May and is now at the University of Chicago.

Kenneth Manzel, Bryan Koestner, and Catherine Cole from the UI are contributing authors on the paper. The National Institute on Aging and the National Institute of Neurological Disorders and Stroke funded the research.

Organisms Cope With Environmental Uncertainty by Guessing the Future (Science Daily)

ScienceDaily (Aug. 16, 2012) — In uncertain environments, organisms not only react to signals, but also use molecular processes to make guesses about the future, according to a study by Markus Arnoldini et al. from ETH Zurich and Eawag, the Swiss Federal Institute of Aquatic Science and Technology. The authors report in PLoS Computational Biology that if environmental signals are unreliable, organisms are expected to evolve the ability to take random decisions about adapting to cope with adverse situations.

Most organisms live in ever-changing environments, and are at times exposed to adverse conditions that are not preceded by any signal. Examples for such conditions include exposure to chemicals or UV light, sudden weather changes or infections by pathogens. Organisms can adapt to withstand the harmful effects of these stresses. Previous experimental work with microorganisms has reported variability in stress responses between genetically identical individuals. The results of the present study suggest that this variation emerges because individual organisms take random decisions, and such variation is beneficial because it helps organisms to reduce the metabolic costs of protection without compromising the overall benefits.

The theoretical results of this study can help to understand why genetically identical organisms often express different traits, an observation that is not explained by the conventional notion of nature and nurture. Future experiments will reveal whether the predictions made by the mathematical model are met in natural systems.