Double-Muscled Hogs

Tuesday, June 30th, 2015

The same myostatin mutation responsible for double-muscled Belgian Blue cattle — and some freakishly muscular humans &mdahs; has been introduced into pigs:

To introduce this mutation in pigs, Kim used a gene-editing technology called a TALEN, which consists of a DNA-cutting enzyme attached to a DNA-binding protein. The protein guides the cutting enzyme to a specific gene inside cells, in this case in MSTN, which it then cuts. The cell’s natural repair system stitches the DNA back together, but some base pairs are often deleted or added in the process, rendering the gene dysfunctional.

The team edited pig fetal cells. After selecting one edited cell in which TALEN had knocked out both copies of the MSTN gene, Kim’s collaborator Xi-jun Yin, an animal-cloning researcher at Yanbian University in Yanji, China, transferred it to an egg cell, and created 32 cloned piglets.

Double-Muscled Hogs

Yin says that preliminary investigations, show that the pigs provide many of the double-muscled cow’s benefits — such as leaner meat and a higher yield of meat per animal. However, they also share some of its problems. Birthing difficulties result from the piglets’ large size, for instance. And only 13 of the 32 lived to 8 months old. Of these, two are still alive, says Yin, and only one is considered healthy.

Rather than trying to create meat from such pigs, Kim and Yin plan to use them to supply sperm that would be sold to farmers for breeding with normal pigs. The resulting offspring, with one disrupted MSTN gene and one normal one, would be healthier, albeit less muscly, they say; the team is now doing the same experiment with another, newer gene-editing technology called CRISPR/Cas9. Last September, researchers reported using a different method of gene editing to develop new breeds of double-muscled cows and double-muscled sheep (C. Proudfoot et al. Transg. Res. 24, 147–153; 2015).

ROV Visitor

Monday, June 8th, 2015

Off the coast of Louisiana, 2,000 feet down, a remotely operated vehicle had a curious visitor. Watch — and listen to the monitoring scientists geek out:

When Birds Squawk, Other Species Listen

Monday, June 1st, 2015

When birds squawk, other species listen:

Studies in recent years by many researchers, including Dr. Greene, have shown that animals such as birds, mammals and even fish recognize the alarm signals of other species. Some can even eavesdrop on one another across classes. Red-breasted nuthatches listen to chickadees. Dozens of birds listen to tufted titmice, who act like the forest’s crossing guards. Squirrels and chipmunks eavesdrop on birds, sometimes adding their own thoughts. In Africa, vervet monkeys recognize predator alarm calls by superb starlings.

[...]

So-called “seet” calls, peeps produced by many small songbirds in response to a raptor on the wing, are well-known to ornithologists. Conventional wisdom held that the calls dissipated quickly and were produced only for other birds nearby. However, that’s not what Dr. Greene noticed: chatter sweeping across the hillside, then birds diving into bushes.

Studying the phenomenon, he documented a “distant early-warning system” among the birds in which the alarm calls were picked up by other birds and passed through the forest at more than 100 miles per hour. Dr. Greene likened it to a bucket brigade at a fire.

The information rippled ahead of a predator minutes before it flew overhead, giving prey time to hide. Moreover, while raptors can hear well at low frequencies, they are not very good at hearing at 6 to 10 kilohertz, the higher frequency at which seet calls are produced. “So it’s sort of a private channel,” he said.

Dr. Greene turned to chickadees, which are highly attuned to threats. When one sees a perched raptor nearby, it will issue its well-known “chick-a-dee” call, a loud, frequent and harsh sound known as a mobbing call because its goal is to attract other birds to harass the predator until it departs.

In 2005, Dr. Greene was an author of an article in the journal Science that demonstrated how black-capped chickadees embed information about the size of predators into these calls. When faced with a high-threat raptor perched nearby, the birds not only call more frequently, they also attach more dee’s to their call.

Raptors tend to be the biggest threat to birds nearest their own size because they can match the maneuverability of their prey. So a large goshawk might only merit a chick-a-dee-dee from a nimble chickadee, while that little pygmy owl will elicit a chick-a-dee followed by five or even 10 or 12 additional dee syllables, Dr. Greene said.

The researchers next showed that red-breasted nuthatches, which are chickadee-size and frequently flock with them in the winter, eavesdrop on their alarm language, too.

Dr. Greene, working with a student, has also found that “squirrels understand ‘bird-ese,’ and birds understand ‘squirrel-ese.’ ” When red squirrels hear a call announcing a dangerous raptor in the air, or they see such a raptor, they will give calls that are acoustically “almost identical” to the birds, Dr. Greene said. (Researchers have found that eastern chipmunks are attuned to mobbing calls by the eastern tufted titmouse, a cousin of the chickadee.)

Hunting and Conserving Rhinos

Wednesday, May 20th, 2015

A Texas hunter bid $350,000 for the right to hunt a rhino in Namibia:

Knowlton’s $350,000 will go to fund government anti-poaching efforts across the country. And the killing of an older rhino bull, which no longer contributes to the gene pool but which could harm or kill younger males, is part of the science of conservation, he argues.

Naturally, this makes him a terrible person:

“I think people have a problem just with the fact that I like to hunt,” Knowlton said. “I want to see the black rhino as abundant as it can be. I believe in the survival of the species.”

Rainbow Lorikeets Eat Meat

Wednesday, April 1st, 2015

Australian rainbow lorikeets eat nectar and pollen — and meat:

For years, Bill, who owns the Elimbah property, has put out pets mince for magpies, currawongs and kookaburras.

He also puts out seed for vegetarian birds like galahs, king parrots and the lorikeets.

He feeds about a dozen birds each day and knows they are spoilt for choice when it comes to food.

Rainbow Lorikeets Eating Meat

Bill’s property is home to native trees and shrubs, and there is untouched forest nearby.

He is happy to offer a few scoops of mince and seed to the birds that come in for a free feed.

It was about seven years ago when Bill first noticed the lorikeets eating meat, and they have been eating it ever since.

“At first they went for the seed but then they started chasing the other birds away from the meat, which surprised me,” he said.

Professor Jones said the availability of food on the property made the lorikeet’s decision to eat meat mystifying.

Does neural crest development drive domestication syndrome?

Monday, March 16th, 2015

Altered neural crest development could be the reason mammals change in oddly consistent ways during domestication:

As first noted by Darwin more than 140 years ago, domestic mammals tend to share certain characteristics—a suite of traits called the domestication syndrome.

The syndrome includes increased docility and tameness, coat color changes, reductions in tooth size, changes in craniofacial morphology, alterations in ear and tail form, more frequent and nonseasonal estrus cycles, alterations in hormone levels, changed concentrations of neurotransmitters, prolonged juvenile behavior, and reduced forebrain size.

Wilkins and Wrangham set about listing these mysterious marks of domestication and trying to match them to tissues affected by the neural crest. Within half an hour they decided that neural crest changes could plausibly account for most of the syndrome’s traits.

The neural crest hypothesis builds on observations from the long-running fox domestication experiments started in 1959 in Novosibirsk, Siberia, by Dmitri Belyaev:

After generations of selection purely for tameness, Novosibirsk foxes today show not only a friendly, people-loving disposition reminiscent of dogs, but also seemingly unrelated traits like curly tails, floppier ears and patches of white fur.

One of the many changes seen in the tame foxes was reduced size and function of their adrenal glands, which release stress hormones during the “fight-or-flight” response. This dampened adrenal function may lie at the heart of the behavioral changes observed in domestication syndrome. Wilkins et al. argue that one way to end up with smaller adrenal glands is via mild deficits of the neural crest.

The neural crest is a cell population that pinches off from the edge of the developing neural tube duing early embryogenesis. These cells migrate to many parts of the body and form the precursors of a plethora of tissue types, including pigment cells, parts of the skull, larynx, ears, teeth, sympathetic nervous system, and, of course, parts of the adrenal glands. So subtle changes in neural crest cell numbers, migration, or proliferation would lead to widespread phenotypic effects.

Neural Crest Domestication Syndrome Schematic

Wilkins et al. argue that their ideas dovetail with certain effects of human neural crest cell disorders, like the patches of depigmented skin and hair seen in Waardenburg syndrome or the jaw, ear and teeth phenotypes of Treacher Collins syndrome.

And even though neural crest cells don’t directly develop into the central nervous system, they could still partly explain why many domestic mammals have smaller forebrains than their wild ancestors. Experiments in chick embryos suggest that signals from neural crest cells play a crucial role in forebrain development. At this stage, not every component of the domestication syndrome can be firmly tied into the hypothesis. For example, the curly tails of dogs, pigs, and domestic foxes don’t have an obvious connection to neural crest deficits. Nonetheless, the authors believe enough links exist to warrant experimental tests of their predictions.

Orca Matriarchs

Wednesday, March 11th, 2015

Female orcas (killer whales) live into their nineties, even though they typically stop breeding at 40. Males only live to 50:

The only other species known to go through a menopause and live so long without reproducing are humans and short-finned pilot whales.

Croft and colleagues watched 750 hours of video of orca family pods. Over 100 individually recognisable orcas were filmed in the coastal Pacific waters off British Columbia and Washington since 1976.

The team found that post-menopausal females were 32 and 57 per cent more likely than non-menopausal adult females or adult males respectively to lead the group. They were also significantly more likely to lead the group in years when their staple food – chinook salmon – was in short supply.

“It’s probably accumulated experience,” says Croft. “Anyone who fishes for migratory trout or salmon will tell you that timing is key, that the fish return in particular cycles of tides and times of the year. Post-menopausal females probably get to know where to look and when.”

[...]

In most known animal species, males rapidly leave their parents, becoming completely independent. Male and female orcas, by contrast, stay in a family unit for life, with the males occasionally exchanging pods temporarily to breed. The upshot, says Croft, is that if females survive for many decades, breeding for the first three or four, their pod becomes increasingly replete with their descendants. Therefore, it becomes more and more in their own interests to safeguard the survival of the pod, and thereby their own genetic legacy.

“There’s a tipping point where they stop reproducing and help their offspring instead, as do grandmothers in the human context,” says Croft.

The findings seem to support the “grandmother hypothesis”, the idea that older women in hunter-gatherer communities evolved to go through the menopause so that they could carry on passing on their wisdom and experience about food sources and other survival tips without the added costs of having more children themselves.

Hunting with Wolves

Tuesday, March 10th, 2015

Modern humans formed an alliance with wolves soon after entering Europe:

We tamed some and the dogs we bred from them were then used to chase prey and to drive off rival carnivores, including lions and leopards, that tried to steal the meat.

“Early wolf-dogs would have tracked and harassed animals like elk and bison and would have hounded them until they tired,” said Shipman. “Then humans would have killed them with spears or bows and arrows.

“This meant the dogs did not need to approach these large cornered animals to finish them off — often the most dangerous part of a hunt — while humans didn’t have to expend energy in tracking and wearing down prey. Dogs would have done that. Then we shared the meat. It was a win-win situation.”

At that time, the European landscape was dominated by mammoths, rhinos, bison and several other large herbivores. Both Neanderthals and modern humans hunted them with spears and possibly bows and arrows. It would have been a tricky business made worse by competition from lions, leopards, hyenas, and other carnivores, including wolves.

“Even if you brought down a bison, within minutes other carnivores would have been lining up to attack you and steal your prey,” said Shipman. The answer, she argues, was the creation of the human-wolf alliance. Previously they separately hunted the same creatures, with mixed results. Once they joined forces, they dominated the food chain in prehistoric Europe — though this success came at a price for other species. First Neanderthals disappeared to be followed by lions, mammoths, hyenas and bison over the succeeding millennia. Humans and hunting dogs were, and still are, a deadly combination, says Shipman.

Humans slowly changed wolves into dogs, but humans may have changed to:

Consider the whites of our eyes, she states. The wolf possesses white sclera as does Homo sapiens though, crucially, it is the only primate that has them.

“The main advantage of having white sclera is that it is very easy to work out what another person is gazing at,” added Shipman. “It provides a very useful form of non-verbal communication and would have been of immense help to early hunters. They would been able to communicate silently but very effectively.”

Thus the mutation conferring white sclera could have become increasingly common among modern humans 40,000 years ago and would have conferred an advantage on those who were hunting with dogs.

(Hat tip to HBD Chick.)

Why They Lost The Wheel

Saturday, March 7th, 2015

Once, in ancient times, the Middle East teemed with carts and wagons and chariots, but they were totally driven out by the coming of the camel:

Good harnesses for camels were designed in Central Asia and, in the 19th century, in the Australian desert, but these did not affect the Middle East.

The only way to make use of this immensely strong beast for transport was to throw the load, averaging anywhere from 300 to 500 pounds, on its back. Thus the pack camel came to compete directly with the ox cart for heavy transport.

The ox cart was equally slow, and in the competition the camel had certain positive advantages. It ate otherwise unusable desert plants, which made its upkeep inexpensive. Little wood, a valuable commodity in the largely deforested Middle East, was required by ancient saddling technology. And its care and breeding could be left to the nomads and thus not be a burden upon the farmer or merchant.

These advantages meant that camel transport was about 20 percent cheaper than wagon transport, according to the edict on prices issued by the Roman emperor Diocletian in the third century A.D. Therefore, simple economic efficiency caused the camel to supplant the wheel, not some mysterious reversion to primitive life.

(Hat tip to commenter Harold!)

Herbivores

Friday, March 6th, 2015

I can still remember some grad students at a party years ago describing what their friends in the biology department had found while doing field work on birds, which they had to temporarily snare to study:

When researchers in North Dakota set up “nest cams” over the nests of song birds, they expected to see a lot of nestlings and eggs get taken by ground squirrels, foxes, and badgers. Squirrels hit thirteen nests, but other meat-eaters made a poor showing. Foxes and weasels only took one nest each. Know what fearsome animal out-did either of those two sleek, resourceful predators?

White-tailed deer.

These supposed herbivores placidly ate living nestlings right out of the nest. And if you’re thinking that it must be a mistake, that the deer were chewing their way through some vegetation and happened to get a mouthful of bird, think again. Up in Canada, a group of ornithologists were studying adult birds. In order to examine them closely, the researchers used “mist-nets.” These nets, usually draped between trees, are designed to trap birds or bats gently so they could be collected, studied, and released. When a herd of deer came by, they deer walked up to the struggling birds and ate them alive, right out of the nets.

This behavior is not limited to one species or one continent. Last year, a farmer in India made a video of a cow eating a recently-hatched chick. Some scientists speculate that herbivores turn to meat when they’re not getting enough nutrients in their diet. It’s possible. A biologist in Scotland documented red deer eating seabird chicks, and concluded it was how they got the dietary boost necessary to grow their antlers. The same researcher also documented sheep eating the heads and legs off of seabird chicks. And then there’s another cow in India, which reportedly ate fifty chickens. There may be a specific need that drives herbivores to occasionally eat meat. It’s also possible, experts say, that eating meat, when it can’t run away from them, is just something supposed “herbivores” do, and we’re finally getting wise to it.

Killers Whales Kill Great White Shark

Sunday, February 8th, 2015

While on a shark-cage diving trip to the Neptune Islands off the coast of Australia, charter operator Matt Waller witnessed killer whales launching themselves out of the water and slamming down on a great white shark:

“If that’s what we’re seeing on the surface, then I can only imagine that under the surface you had other whales that were working to try and keep this shark up,” he said.

“It never actually went down. It stayed on the surface and was trying to get away.”

Go mammals!

The Fantastic Fur of Sea Otters

Friday, January 9th, 2015

How do sea otters stay lean yet keep warm? Through their fantastic fur, KQED’s Deep Look explains:

Bluefin Tuna Sold for $37,500

Friday, January 9th, 2015

The Japanese treasure the rich red meat of hon-maguro, and a single bluefin tuna can sell for $1.5 million, or $3,000 a pound — as a publicity stunt. This year one sold for “just” $37,500:

A sushi restaurant chain owner paid ¥4.51 million ($37,500) for a 180 kilogram Bluefin tuna at the first auction of the year in Tokyo’s Tsukiji fish market.

Kiyoshi Kimura, president of Kiyomura Co., has won the year’s first bid for four consecutive years since 2012. He told reporters Monday after his purchase that it was cheaper than he had expected thanks to a successful haul of tuna near the Tsugaru strait this year.

While $37,500 may seem too much to pay for a fish, it is a bargain compared to what Mr. Kimura had to spend in 2013.

In January 2012, Mr. Kimura won the bid at the first tuna auction of the year for $736,700. He then paid $1.76 million for a 222 kilogram tuna in January 2013, which remains an all-time record.

Ebola’s Reservoir Host

Tuesday, January 6th, 2015

The Ebola virus only occasionally spills over into humans from its reservoir host — but what is Ebola’s reservoir host?

Surveying wildlife in forests [near the borders of Liberia and Ivory Coast], the scientists found no evidence of a die-off among larger animals, such as duikers, monkeys, and chimpanzees, that are also susceptible to Ebola. This suggested that perhaps the virus had spilled over directly from its reservoir host into humans, without passing through other animals hunted or scavenged for food.

The team then focused on a village called Méliandou, in Guinea — the index village, where the human outbreak began. A young boy, Emile Ouamouno, was the earliest known victim. He died with Ebola-like symptoms in Méliandou back in December 2013, followed soon by his mother, sister, and grandmother. No adult males died in the first wave of the outbreak, another clue that seemed to point away from hunted wildlife as the origin of the virus.

During eight days in Méliandou, Leendertz’s team gathered testimony from survivors and collected samples, including blood and tissues from captured bats. From these data emerged the new hypothesis: Maybe the reservoir host was a bat, yes — but a very different sort of bat, in a different ecological relationship with humans.

While fruit bats are abundant in southeastern Guinea, they don’t roost in large aggregations near Méliandou. But the village did harbor a sizable number of small, insectivorous bats, which roosted under the roofs of houses and in natural recesses, such as hollow trees. The locals call them lolibelo.

“These bats are reportedly targeted by children,” the new paper recounts, “who regularly hunt and grill them over small fires.” Imagine a marshmallow roast, except the marshmallows are mouse-size bats devoured by protein-hungry children.

Dissected Angolan Free-Tailed Bat

The researchers then uncovered another clue: a large hollow tree, which had recently been set afire, producing as it burned what someone recalled as “a rain of bats.” Leendertz’s team collected soil samples at the base of that tree, which eventually yielded traces of DNA assignable to Mops condylurus, commonly called the Angolan free-tailed bat.

That species matched the villagers’ descriptions of lolibelo. What’s more, the big hollow tree had reportedly been a favorite play spot for small children of the village, including the deceased little boy, despite — or perhaps because of — the fact that it was full of little bats.

Norwegian Lemmings

Sunday, December 14th, 2014

Norwegian LemmingNorwegian lemmings go through dramatic population cycles, with their density increasing and then decreasing by a factor of 3,000:

Accounts of lemming migrations go back hundreds of years. In 1823, for instance, one explorer wrote of seeing “such inconceivable numbers” in his Scandinavian travels “that the country is literally covered with them”.

An army of lemmings advanced with extraordinary purpose, “never suffering itself to be diverted from its course by any opposing obstacles,” not even when confronted by rivers, or even the branches of narrow fjords. “They are good at swimming,” says Stenseth. “They can easily go across small bodies of water, across small lakes,” he says.

Given such sudden and apparently reckless behaviour, it is perhaps inevitable that local people in bygone centuries came to see the lemming as a crazed creature, and a swarm as “the forerunner of war and disaster”. But we have Walt Disney to thank for really embedding this stereotype in the public consciousness.

On the back of the animated classic Bambi, Disney undertook a series of ground-breaking, feature-length nature documentaries known as The True-Life Adventures. In one of these, White Wilderness, he dramatised the lemming mass suicide.

Stenseth is generous about the movie. “It is a nice film actually,” he says. “But there are some bits and pieces that are wrong with it. That [the lemming segment] is one of them.”

For a start, White Wilderness – filmed in Canada rather than Scandinavia – depicts the wrong species. Although all lemmings experience population highs and lows, the accounts of mass movements were all based on observations of Norwegian lemmings, not the brown lemmings that Disney used. He paid Eskimos “$1 a live lemming,” says Stenseth.

But that’s just the start. In an infamous sequence, the lemmings reach the edge of a precipitous cliff, and the voiceover tells us that “this is the last chance to turn back, yet over they go, casting themselves bodily out into space.”

It certainly looks like suicide. “Only they didn’t march to the sea,” says Stenseth. “They were tipped into it from the truck.”

Once you know the sequence has been faked, it makes for rather awkward viewing.

That movie-fueled myth did lead to a delightful computer game though.