Woolly mammoth DNA may lead to a resurrection of the ancient beast

Technical and ethical challenges abound after first hurdle of taking cells from millennia-old bodies is cleared

baby mammoth carcass

Even a well-preserved carcass like this baby woolly mammoth is unlikely to provide viable cells for cloning, as used to create Dolly. Photograph: Aaron Tam/Getty

By Ian Wilmut

It is unlikely that a mammoth could be cloned in the way we created Dolly the sheep, as has been proposed following the discovery of mammoth bones in northern Siberia. However, the idea prompts us to consider the feasibility of other avenues. Even if the Dolly method is not possible, there are other ways in which it would be biologically interesting to work with viable mammoth cells if they can be found.

In order for a Dolly-like clone to be born it is necessary to have females of a closely related species to provide unfertilised eggs, and, if cloned embryos are produced, to carry the pregnancies. Cloning depends on having two cells. One is an egg recovered from an animal around the time when usually she would be mated.

In reality there would be a need for not just one, but several hundred or even several thousand eggs to allow an opportunity to optimise the cloning techniques. The cloning procedure is very inefficient. After all, after several years of research with sheep eggs, Dolly was the only one to develop from 277 cloned embryos. In species in which research has continued, the typical success rate is still only around 5% at best.

Elephant eggs

_MG_0350

Photo: Rubén Portas

In this case the suggestion is to use eggs from elephants. Because there is a danger of elephants becoming extinct it is clearly not appropriate to try to obtain 500 eggs from elephants. But there is an alternative.

There is a considerable similarity in the mechanisms that regulate function of the ovaries in different mammals. It has been shown that maturation of elephant eggs is stimulated if ovarian tissue from elephants is transplanted into mice.

In this way it might be possible to obtain a considerable number of elephant eggs over a period of time if ovarian tissue is obtained from elephants that die.

Cells from mammoths are required to provide the genetic information to control development. The suggestion is to recover cells from the marrow of bones emerging from the frozen north of Siberia. However, these cells will degenerate rapidly at the temperature of melting snow and ice. This means that cells in the bones may well become useless for this capacity as they thaw.

The chances of cells being viable would be increased if bones could be recovered from the lowest possible temperature rather than waiting until they emerge from snow. The cells can then be warmed rapidly. Alternatively, the nuclei could be transferred directly into eggs.

The very first stages of embryo development are controlled by proteins that are in the egg when it is shed by the ovary. One for example has a critical role in cell division. Together these proteins have an extraordinary ability to repair damaged nuclei so it may not be strictly necessary for the cells to be viable. It would be best if the mammoth nucleus could be introduced into an egg immediately, by injection of the contents of the damaged cell into the egg.

Research in 2008 found that when nuclei from freeze-dried sheep cells were transferred into eggs, some of the cloned embryos developed for a few days, but not to term. This was a very clear indication of the ability of the egg to repair damaged nuclei. However, freeze-dried cells are likely to be more stable than those that have been frozen with liquid still present. In the case of the mammoth, the cells would likely be killed by large ice crystals formed from the liquid.

Finally, if embryos that developed normally for a few days could be produced, they would have to be transferred to surrogate mothers to develop through pregnancy. Embryo transfer is only carried out routinely in fewer than a dozen species, and the elephant is not one of them. Success in embryo transfer depends upon introducing the embryo to a womb that is in a receptive state. The mechanisms that bring about this state in elephants are currently being defined by research in a number of zoos.

Taken together, it can be seen that there is biological uncertainty about the availability of viable cells, and that several complex techniques would have to be developed for cloning of mammoths to be successful. There is no guarantee that these techniques are even biologically possible. There may be unknown differences between species that would prevent the procedures that we developed in sheep being successful in mammoths.

Copyright: Royal BC Museum

Mammoth stem cells
An alternative ambition would be to try to use mammoth cells to produce stem cells. In several different species it is possible simply by the introduction of four selected proteins to give adult cells the characteristics of embryo stem cells. The four factors give embryo stem cells their unique characteristics and were found to be able to impose these characteristics on skin cells. This type of stem cell can be grown for very long periods in the laboratory while retaining the ability to form all of the tissues of the body.

They would provide extraordinary opportunities to compare mammoth cells with those of elephants. This knowledge would be of fundamental biological interest. It would enable us to begin to answer groundbreaking questions. What are the differences between the cells and tissues of these species? What are the similarities? The mammoth lived in a different climate, so was the metabolism of their cells different? Does this information cast any light on the cause of extinction of mammoths?

Stem cells of this type can also be induced to form gametes. If the cells were from a female, this might provide an alternative source of eggs for use in research, and perhaps in breeding, including the cloning of mammoths.

From a male, they would be sperm, and they might be able to fertilise eggs to produce a new mammoth embryo. It would be interesting to know if mammoth sperm could fertilise eggs of the elephant. If so, would the embryos develop to term to produce a hybrid animal?

Only a small proportion of mixed matings between species produces viable offspring, but the mule is one example and has been used by humans for centuries.

In all of these discussions it is necessary to consider the welfare of the animals. Mammoths lived in cold climates, whereas their current relatives including potential surrogate mothers live in warmer regions.

It would be essential to provide mother and clone with the appropriate environment of temperature, moisture and diet. It would almost certainly be necessary to keep the animals in captivity, so it would be essential to provide as interesting an environment as possible. Ideally this should include other elephants, mammoths or hybrids to provide social interaction for the animal.

So while unlikely at present, the development of some form of mammoth creature or hybrid might be possible in the longer term, the research of which could lead to major biological discoveries and advances.

This is another area of biology where studies of stem cells would be very rewarding. In stem cell research rather than cloning there would also be fewer concerns over animal welfare, or the effect of the animal on the environment. All in all, research to produce mammoth stem cells would be the appropriate choice, and extraordinarily scientifically rewarding, should it be possible to find viable mammoth cells.

Sources:

http://theconversation.com/produce-mammoth-stem-cells-says-creator-of-dolly-the-sheep-16335

http://www.theguardian.com/science/2013/jul/31/woolly-mammoth-dna-cloning

The Hearty Ingredients of Canis Soup

By The Dog Zombie | December 27, 2011 |

The wolf is iconic and charismatic. We see him on t-shirts, on posters, and in fantasy novels. Conservationists do battle with ranchers to preserve populations of wolves. The coyote, on the other hand, is neither iconic nor loved. A newcomer to suburbia, he is feared as a suspected predator of cats, small dogs, and even small children. He is rarely seen on t-shirts; his name is not used to designate a rank of Boy Scout.

But now that we have the genetic tools to look at these animals’ genomes, it turns out that many of the populations of coyotes in North America are actually coyote-wolf hybrids, as are many of the populations of wolves. Unable to draw clear lines between these species, biologists have dubbed the populations of hybrids “Canis soup.”

What’s a Canis?

The term “canid soup” has also been used for this mess of wolf, coyote, and even dog genes that we find in some populations of canids. So what does Canis mean, and what is a canid?

These are terms related to the scientific classification of the species in question. Going through the hierarchy, we have Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Carnivora, Family Canidae (canids), and Genus Canis. Wolves, dogs, jackals, and foxes belong to the family Canidae, but only wolves, dogs, and jackals (not foxes) belong to the genus Canis. We call the wolf-like canids “canines” and the fox-like canids “vulpines.”

As foxes do not interbreed with wolves, dogs, or jackals, what we’re talking about here is correctly Canis soup, or perhaps canine soup, but not canid soup.

Is it Canis or is it soup?

The more you dig into wild canines in North America, the more unclear it is where any species lines should be drawn. So who makes up our cast of characters?

The first ingredient in Canis soup is the charismatic North American gray wolf or timber wolf, Canis lupus, sometimes known as Canis lupus lupus to differentiate it from the dog and the dingo, who belong to subspecies. The gray wolf is the largest wild canine, at a 79 pound (36 kg) average weight. (Domestic dogs of some breeds, of course, weigh more than that.) Its coat coloring can vary from white through blond, brown, grey, and black. It is found in the western parts of North America.

Next is the Western coyote, Canis latrans. This animal is also known as the American jackal or prairie wolf, suggesting that there has been some confusion about how to distinguish canine species for some time. The Western coyote is a significantly smaller animal than the gray wolf, weighing in closer to 20 pounds (7-14 kg). Its coat color is less varied than the gray wolf’s, almost always a grey-brown as you see in the image here.

The range of the Eastern wolf or Algonquin wolf, Canis lycaon, is Ontario, Canada. This wolf is smaller than the gray wolf, and has a distinctive grey-red coat with black hairs along its back. We believe that this wolf was the original North American canine, and thatCanis lupus andCanis latransimmigrated over the land bridge from Europe. There’s a lot of debate about the species status of C. lycaon, as many Eastern wolves appear to have significant C. latrans heritage. Some people suggest that the Eastern wolf is in fact a C. lupus/C. latrans hybrid, or, alternately, a subspecies of the gray wolf, C. lupus lycaon.

The Eastern coyote, spreading along the east coast of the United States, is significantly larger than his Western counterpart. It turns out to be a coyote/wolf hybrid, and it has been argued that it should more accurately be called a coywolf. His wolf ancestors seem to beCanis lycaon —  but then again, there is debate about whether C. lycaon is really different from C. lupus at all.

The red wolf or Southeastern wolf is subject to truly intense debate about species status. Is it his own species, Canis rufus? A subset of the gray wolf, Canis lupus rufus? Or a population of Eastern wolf, Canis lycaon? It has a beautiful red coat, and is smaller in size than the gray wolf. Its range was historically the southeastern U.S., but it went extinct in the wild by 1980. A founder population of 19 animals survived in captivity, and a reintroduction project in North Carolina was begun in 1987. Here the red wolf is today enthusiastically interbreeding with coyotes, leaving conservationists to wonder what they are conserving.

The three species of wild canines in North America today, then, are Canis lupus, Canis latrans, and Canis lycaon. But we really have just two soup ingredients, wolf and coyote. There are pure wolves (Canis lupus) and there are pure coyotes (Canis latrans), and there are populations that are mixtures of more or less wolf and more or less coyote (Eastern wolves, Eastern coyotes, and red wolves). There appears to be some dog mixed in there, too. You can think of gray wolf and Western coyote as ingredients, and everything else as soup.

Coyote flavor versus wolf flavor

The 2011 paper “A genome-wide perspective on the evolutionary history of enigmatic wolf-like canids” analyzed the various soup flavors out there and presented their findings in some easy-to-understand charts (below). Here, the different colors represent different amounts of each ingredient. The first chart describes the Eastern wolf, here referred to as the Algonquin wolf, which is mostly gray wolf (green) and joint wolf/coyote (yellow), but also has significant coyote (red). The second chart describes the red wolf; at a glance, it is obvious that the red wolf has a much larger percentage of coyote genes (again, red in this chart). These charts both use τ to denote the number of generations since the most recent admixture with another species.

The two coyote recipes pictured below describe two subpopulations of what I have described as the Eastern coyote; this particular paper considers them split into Northeastern and Southeastern coyotes. At a glance, these populations are mainly pure coyote (red), with big dashes of mixed coyote/wolf (yellow), and small but notable amounts of our friend the dog (dark blue, light blue, and pink).

Wild canine populations challenge us to let go of our obsessive need to categorize. Instead of slotting a canine population into a single species category, we might instead think of it as existing on a spectrum from “wolf-like” to “coyote-like.” A strongly wolf-like canid would be larger, sixty to ninety pounds. It would require a larger range, and would be a deerivore, subsisting off of larger game. It is likely to be a shyer animal, found only in more rural or wild areas. Conversely, a strongly coyote-like canid would be much smaller, fifteen to thirty pounds, with a smaller range. It might eat deer as well as rabbits and et cetera (probably a lot of et cetera, as coyotes are more willing to scrounge than wolves are). It would be more likely to be found in suburban areas, with a greater tolerance for human proximity. A given population of canines might fall anywhere on the spectrum between the two. The fact that a spectrum actually exists is beautifully demonstrated by the Eastern coyote, who has mixed coyote/wolf ancestry, is mid-sized between coyote and wolf, and has a mid-sized range.

What’s your preferred flavor?

Does the intermixture of various ingredients in the formation of soupy populations matter as more than a gee-whiz story? To some people, the answer is very much yes. The conservationists who are committing significant resources to the preservation of the red wolf don’t want to see the wolves that they reintroduce interbreed with coyotes. If the reintroduced wolf population blends into a coyote population, then are these resources actually being spent just to support a bunch of coyotes (who have been doing fine on their own)? At the same time, evidence shows that the founder population of 19 red wolves was already significantly coyotified, and we’re not sure how long it’s been since there have been any pure Canis rufus specimens in North America.

It is, of course, possible to think about the problem without asking for genetics to provide the complete answer for us. The red wolf is a red wolf, a beautiful, iconic animal that has lived in the southeastern United States throughout living memory. We know what the red wolf looks like (and that hasn’t been changing much, no matter what is happening to his genes). We also know that it is important in a particular environmental niche, and that hasn’t been changing much either.

Practically, the mixture of coyote genes into fragile wolf populations may be a good thing. Because coyotes are better at living on smaller ranges and in closer proximity to humans than wolves are, they are better adapted to the realities of North America today. As their genes mix into wolf populations, these populations become demonstrably more robust, more able to tolerate human presence, and able to survive on smaller ranges. It is possible, in fact, that coyote genes are exactly what are eventually going to allow a red wolf population to flourish without human assistance.

Conclusions, if we can make any

Does it matter that some of what we think of as wolves have coyote genes? I think the answer comes down to a cultural perception of the wolf as a romantic and charismatic creature, and of the coyote as a pest. Perhaps any mixture of the two is perceived as diminishing the wolf. A friend of mine once made this analogy: if you have an entire bottle of fine wine, and you pour just a teaspoon of sewage into it, now you have a bottle of sewage. Does any amount of coyote, no matter how miniscule, make the wolf impure, and less worth conserving than it was?

As a culture, I hope we can come to appreciate the strengths that the coyote brings to Canis soup, in its ability to coexist with humans in the modern world. It may be what saves populations of charismatic wolves from permanent loss. As we look at populations of canines in North America, we should learn to say that one is more coyote-like and another more wolf-like, on a spectrum from one flavor of soup to another, and appreciate the benefits of both.

Canis soup has been used before as an example of the blurriness of some species lines and the inadequacy of many existing definitions of a species, but it also provides some interesting insights into the fluidity of canid morphology and behavioral characteristics. How did something as large and wild as a wolf become something as variably-sized and tame as a dog? Moreover, how did this change happen (presumably) without a carefully planned breeding program? Why is it so easy to breed types of dogs with such different behavioral and physical characteristics, especially compared to the much more limited variety of breeds of cat, horse, or cow? The canine genome clearly has the capacity for expression across a startlingly wide array of phenotypes. The evidence of this variety has always been right before our eyes, but we are just beginning to understand its implications.

References:

· Adams J. R., Leonard J. A., Waits L. P. Widespread occurrence of a domestic dog mitochondrial DNA haplotype in southeastern US coyotes. Molecular Ecology. 2003;12:541-546.
· Adams J. R., Kelly B. T., Waits L. P. Using faecal DNA sampling and GIS to monitor hybridization between red wolves (Canis rufus) and coyotes (Canis latrans).Molecular Ecology. 2003;12:2175-2186.
· Hailer Frank, Leonard Jennifer A. Hybridization among three native North American Canis species in a region of natural sympatry. PLoS ONE. 2008;3:e3333+.
· vonHoldt Bridgett M., Pollinger John P., Earl Dent A., et al. A genome-wide perspective on the evolutionary history of enigmatic wolf-like canids. Genome research. 2011;21:1294-1305.
· Way Jonathan G., Rutledge Linda, Wheeldon Tyler, White Bradley N. Genetic Characterization of Eastern ”Coyotes” in Eastern Massachusetts. Northeastern Naturalist. 2010;17:189-204.
· Wilson Paul J., Grewal Sonya K., Mallory Frank F., White Bradley N. Genetic Characterization of Hybrid Wolves across Ontario. Journal of Heredity. 2009;100:S80-S89.
· Zimmer Carl. What Is a Species? Sci Am. 2008;298:72-79.

Images: Gray Wolf (Image courtesy of vargklo at Wikipedia and Flickr); Western Coyote (Image courtesy of Rebecca Richardson at Wikipedia and Flickr); Eastern wolf (Image courtesy Christian Jansky at Wikipedia); Eastern coyote/coywolf (Image fromEastern Coyote Research); Red wolf (image from True Wild Life); Two recipes for wolf flavored Canis soup (vonHoldt, 2011); Two recipes for coyote flavored Canis soup (vonHoldt, 2011)

Source: http://blogs.scientificamerican.com/guest-blog/2011/12/27/the-hearty-ingredients-of-canis-soup/

No genetic flow found in two Tigrina populations leads to a new Tigrina species

Leopardus tigrinus can be found in Eastern Amazonia or the dry semi-arid Caatinga. Project Wild Cats of Brazil

A new species of wild cat in central and north-eastern Brazil has been confirmed, according to a study published today in the journal Current Biology.

This recognition formally separates the two known tigrina species (Leopardus tigrinus and Leopardus guttulus) which, until now, were regarded as one.

According to the authors of the study, Eduardo Eizirik from the Pontifical Catholic University of Rio Grande do Sul and Tatiane Trigo from the University Federal of Rio Grande do Sul, the possibility that these two wild cat populations were two distinct species was considered in the 1960s, but the hypothesis was never tested.

For the first time, scientists are able to assess the two previously-recognised subspecies using molecular markers to analyse their genetic relationship.

The results showed that the housecat-sized tigrina populations are, in fact, completely separate species.

“Our analysis showed strong genetic differentiation between the tigrina populations, with no gene flow between them, indicating that these two populations are actually reproductively isolated and should be recognised as distinct species,” said Professor Eizirik and Dr Trigo.

L. guttulus is found in southern and south-eastern Brazil. Project Wild Cats of Brazil
Click to enlarge

Data on the two tigrina species also revealed a distinct geographical distribution of both populations.

L. tigrinus, found in central and north-eastern Brazil, live primarily in open and dry vegetation (shrublands and savannahs). The southern and south-eastern Brazilian areas, occupied by L. guttulus, are dominated by denser and wetter Atlantic forest-type habitats.

Such distinct habitat conditions provide clues to their different ecological requirements and the adaptive differences that may have been responsible for their evolutionary divergence.

Hybridisation

The findings from this study also revealed the complexity of the relationships between the tigrinas and two other species of neotropical cats (commonly known as Geoffroy’s cats).

The evidence suggests that L. tigrinus’ evolutionary history includes hybridisation and movement of genes between them and the pampas cat, while extreme levels of interbreeding between L. guttulus and Geoffroy’s cats still occur along their contact zone.

Although there is no evidence that this interbreeding is expanding beyond the contact zone, it is clear that hybridisation can and does occur between distinct animal species.

Christopher Johnson, a professor of wildlife conservation from the University of Tasmania, said: “This study hints that hybridisation in the past has accelerated speciation. The acquisition of new genes by hybridisation can be a potent force in the evolution of species, and this could be a neat example where hybridisation in some parts of the range but not others has contributed to splitting of one species into two.

“We used to think that hybridisation between related species was not supposed to happen – by definition, species did not interbreed – but it’s clearly more significant than was realised.”

L. tigrinus. Project Wild Cats of Brazil
Click to enlarge

Professor Eizirik and Dr Trigo explained that hybridisation may occur quite frequently in the initial stages of species divergence, and the species involved may hybridise for some time and maintain a hybrid zone at their region of geographic overlap.

However, this may not necessarily lead to their complete admixture or the loss of the genetic and phenotypic integrity of each parental species.

“Currently, there is a strong genetic differentiation between these two cat species in areas farther from the contact zone. Selective pressure must be keeping the two species morphologically, ecologically, and even genetically distinct outside of this contact zone.

“Therefore, at this point, it seems adequate to keep them as separate species and continue to investigate the extent and biological consequences of their hybridisation.”

Implications on conservation

Gerry Ryan, from the University of Melbourne, warned that the evidence for a recent or continuing hybrid zone between the southern tigrinas and Geoffroy’s cats will need closer investigation to determine if any conservation management actions are needed.

“The two tigrina species are listed as one on the IUCN’s Red List of Threatened Species. Now that they are considered to be separate species, they both need to be re-assessed. Each one will be at a higher risk of extinction, than when considered as one species, because smaller numbers automatically increase the risks.

“If the hybridisation is spurred by human-induced habitat alteration, then conservation management actions must be considered. But, given the already extensive gene flow, this may be too late.”

Much more is known about the southern L. guttulus than the northeastern tigrinas. Project Wild Cats of Brazil
Click to enlarge

Hamish Campbell, from the University of Queensland, believes that the use of modern genetic techniques is crucial in determining when one species or sub-species should be declared distinct from another, particularly when it comes to managing rare and threatened species.

He explained: “This study is similar to that of the Scottish wildcat (Felis silvestris) which, using molecular techniques, was found to be breeding with feral domestic cats (Felis felis).

“Feral domestic cats are an environmental disaster, devastating native wildlife, while the Scottish wildcat is a rare and ancient species that needs to be conserved. But where do you draw the eradication line? What level of hybridisation is acceptable to declare the species a threat rather than a pest?

“Molecular techniques are helping us to map the evolutionary history of species, but how those findings are applied to the successful management of rare and threatened species is still in its infancy.”

Future studies

According to Gerry Ryan, this case study shows us how modern genetic techniques can help clarify cryptic patterns of species diversity.

“As genetics and genomics continue to advance and be cheaper and faster, we can better understand the complex and dynamic nature of species boundary. We will then need to develop parallel conservation strategies to protect the diversity of life beyond linear concepts, and allow for adaptation and evolution in the face of global climactic change.”

A close-up photo of the enigmatic L. guttulus. Project Wild Cats of Brazil
Click to enlarge

Professor Eizirik and Dr Trigo agreed, saying: “Our study has opened new avenues for research, focusing on more in-depth evolutionary, genomic, morphological and ecological questions.

“We intend to further investigate Brazilian northeastern tigrinas which are virtually unknown with respect to most aspects of their biology. Some initial studies on its ecology (diet, feeding habits and habitat requirements) have been done, but information on its population density, habitat use and population trends remain unknown.

“There is also very little information on the ecological segregation between the two species. Thus, we consider studying L. tigrinus a priority for research and conservation actions.”

Source: http://theconversation.com/one-becomes-two-genes-show-brazilian-wild-cat-is-two-species-20793

Free access to the original scientific paper: http://www.cell.com/current-biology/retrieve/pii/S0960982213013213

The Secrets of Owls’ Near Noiseless Wings

Many owl species have developed specialized plumage to effectively eliminate the aerodynamic noise from their wings — allowing them to hunt and capture their prey in silence.

A research group working to solve the mystery of exactly how owls achieve this acoustic stealth will present their findings at the American Physical Society’s (APS) Division of Fluid Dynamics meeting, held Nov. 24 — 26, in Pittsburgh, Pa. — work that may one day help bring “silent owl technology” to the design of aircraft, wind turbines, and submarines.

“Owls possess no fewer than three distinct physical attributes that are thought to contribute to their silent flight capability: a comb of stiff feathers along the leading edge of the wing; a flexible fringe a the trailing edge of the wing; and a soft, downy material distributed on the top of the wing,” explained Justin Jaworski, assistant professor in Lehigh University’s Department of Mechanical Engineering and Mechanics. His group is exploring whether owl stealth is based upon a single attribute or the interaction of a combination of attributes.

For conventional wings, the sound from the hard trailing edge typically dominates the acoustic signature. But prior theoretical work carried out by Jaworski and Nigel Peake at the University of Cambridge revealed that the porous, compliant character of the owl wing’s trailing edge results in significant aerodynamic noise reductions.

“We also predicted that the dominant edge-noise source could be effectively eliminated with properly tuned porous or elastic edge properties, which implies that that the noise signature from the wing can then be dictated by otherwise minor noise mechanisms such as the ‘roughness’ of the wing surface,” said Jaworski.

The velvety down atop an owl’s wing creates a compliant but rough surface, much like a soft carpet. This down material may be the least studied of the unique owl noise attributes, but Jaworski believes it may eliminate sound at the source through a novel mechanism that is much different than those of ordinary sound absorbers.

“Our current work predicts the sound resulting from air passing over the downy material, which is idealized as a collection of individual flexible fibers, and how the aerodynamic noise level varies with fiber composition,” Jaworski said.

The researchers’ results are providing details about how a fuzzy — compliant but rough — surface can be designed to tailor its acoustic signature.

A photographic study of actual owl feathers, carried out with Ian Clark of Virginia Tech, has revealed a surprising ‘forest-like’ geometry of the down material, so this will be incorporated into the researchers’ future theoretical and experimental work to more faithfully replicate the down structure. Preliminary experiments performed at Virginia Tech show that a simple mesh covering, which replicates the top layer of the ‘forest’ structure, is effective in eliminating some sound generated by rough surfaces.

“If the noise-reduction mechanism of the owl down can be established, there may be far-reaching implications to the design of novel sound-absorbing liners, the use of flexible roughness to affect trailing-edge noise and vibrations for aircraft and wind turbines, and the mitigation of underwater noise from naval vessels,” said Jaworski.

The above story is based on materials provided by American Physical Society’s Division of Fluid Dynamics, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

American Physical Society’s Division of Fluid Dynamics (2013, November 24). The secrets of owls’ near noiseless wings. ScienceDaily. Retrieved November 28, 2013,

Source: http://www.sciencedaily.com­/releases/2013/11/131124093515.htm

Dogs likely originated in Europe more than 18,000 years ago, UCLA biologists report

By Stuart Wolpert November 14, 2013
Wolves likely were domesticated by European hunter–gatherers more than 18,000 years ago and gradually evolved into dogs that became household pets, UCLA life scientists report.

“We found that instead of recent wolves being closest to domestic dogs, ancient European wolves were directly related to them,” said Robert Wayne, a professor of ecology and evolutionary biology in UCLA’s College of Letters and Science and senior author of the research. “This brings the genetic record into agreement with the archaeological record. Europe is where the oldest dogs are found.”
Ancient dog fossil A fossil of a dog that lived approximately 8,500 years ago, from the Koster archaeological site in Illinois. (Credit: Del Baston)
The UCLA researchers’ genetic analysis is published Nov. 15 in the journal Science and featured on the journal’s cover.

In related research last May, Wayne and his colleagues reported at the Biology of Genomes meeting in New York the results of their comparison of the complete nuclear genomes of three recent wolf breeds (from the Middle East, East Asia and Europe), two ancient dog breeds and the boxer dog breed.

“We analyzed those six genomes with cutting-edge approaches and found that none of those wolf populations seemed to be closest to domestic dogs,” Wayne said. “We thought one of them would be, because they represent wolves from the three possible centers of dog domestication, but none was. All the wolves formed their own group, and all the dogs formed another group.”

The UCLA biologists also hypothesized at that conference that a now-extinct population of wolves was more directly related to dogs.

For the current study in Science, the researchers studied 10 ancient “wolf-like” animals and eight “dog-like” animals, mostly from Europe. These animals were all more than 1,000 years old, most were thousands of years old, and two were more than 30,000 years old.

The biologists studied the mitochondrial DNA of the animals, which is abundant in ancient remains. (Mitochondria are tiny sub-cellular structures with their own small genome.) By comparing this ancient mitochondrial DNA with the modern mitochondrial genomes of 77 domestic dogs, 49 wolves and four coyotes, the researchers determined that the domestic dogs were genetically grouped with ancient wolves or dogs from Europe — not with wolves found anywhere else in the world or even with modern European wolves. Dogs, they concluded, derived from ancient wolves that inhabited Europe and are now extinct.

Wayne said that that the domestication of predatory wolves likely occurred among ancient hunter–gatherer groups rather than as part of humans’ development of sedentary, agricultural-based communities.

“The wolf is the first domesticated species and the only large carnivore humans ever domesticated,” Wayne said. “This always seemed odd to me. Other wild species were domesticated in association with the development of agriculture and then needed to exist in close proximity to humans. This would be a difficult position for a large, aggressive predator. But if domestication occurred in association with hunter–gatherers, one can imagine wolves first taking advantage of the carcasses that humans left behind — a natural role for any large carnivore — and then over time moving more closely into the human niche through a co-evolutionary process.”

The idea of wolves following hunter–gatherers also helps to explain the eventual genetic divergence that led to the appearance of dogs, he said. Wolves following the migratory patterns of these early human groups would have given up their territoriality and would have been less likely to reproduce with resident territorial wolves. Wayne noted that a group of modern wolves illustrates this process.
“We have an analog of this process today, in the only migratory population of wolves known existing in the tundra and boreal forest of North America,” he said. “This population follows the barren-ground caribou during their thousand-kilometer migration. When these wolves return from the tundra to the boreal forest during the winter, they do not reproduce with resident wolves there that never migrate. We feel this is a model for domestication and the reproductive divergence of the earliest dogs from wild wolves.

“We know also that there were distinct wolf populations existing ten of thousands of years ago,” Wayne added. “One such wolf, which we call the megafaunal wolf, preyed on large game such as horses, bison and perhaps very young mammoths. Isotope data show that they ate these species, and the dog may have been derived from a wolf similar to these ancient wolves in the late Pleistocene of Europe.”

In research published in the journal nature in 2010, Wayne and colleagues reported that dogs seem to share more genetic similarity with living Middle Eastern gray wolves than with any other wolf population, which suggested a Middle East origin for modern dogs. The new genetic data have convinced him otherwise.

“When we previously found some similarity between Middle Eastern wolves and domestic dogs, that similarity, we are now able to show, likely was the result of interbreeding between dog and wolves during dog history. It does not necessarily suggest an origin in the Middle East,” Wayne said. “This alternative hypothesis, in retrospect, is one that we should have considered more closely. As hunter–gatherers moved around the globe, their dogs trailing behind probably interbred with wolves.”

Wayne considers the new genetic data “persuasive” but said they need to be confirmed with an analysis of genetic sequences from the nucleus of the cell (roughly 2 billion base pairs) — a significantly larger sample than that found in mitochondrial DNA (approximately 20,000 base pairs). This is challenging because the nuclear DNA of ancient remains tends to become degraded.

While Wayne plans to pursue this follow-up research, he said he does not expect a nuclear genome analysis to change the central finding. However, he said, it will fill in more of the details.

“This is not the end-story in the debate about dog domestication, but I think it is a powerful argument opposing other hypotheses of origin,” he said.

There is a scientific debate over when dogs were domesticated and whether it was linked with the development of agriculture fewer than 10,000 years ago, or whether it occurred much earlier. In the new Science research, Wayne and his colleagues estimate that dogs were domesticated between 18,000 and 32,000 years ago.

The research was federally funded by the National Science Foundation.

Co-authors on the Science paper include Olaf Thalmann, a former postdoctoral scholar in Wayne’s laboratory who is currently the Marie Curie Postdoctoral Fellow at Finland’s University of Turku; Daniel Greenfield, a former technician in Wayne’s laboratory; Francesc López-Giráldez, a former graduate student in Wayne’s laboratory who is currently a postdoctoral scholar at Yale University; Adam Freedman, a former postdoctoral scholar in Wayne’s laboratory; Rena Schweizer, a current UCLA graduate student in Wayne’s laboratory; Klaus Koepfli, a former postdoctoral scholar in Wayne’s laboratory; and Jennifer Leonard, who earned her doctorate from UCLA.

Approximately 80 percent of dog breeds are modern breeds that evolved in the last few hundred years, Wayne said. But some dog breeds have ancient histories that go back thousands of years.

Wolves have been in the Old World for hundreds of thousands of years. The oldest dogs from the archaeological record come from Europe and Western Russia. A dog from Belgium dates back approximately 36,000 years, and a group of dogs from Western Russia is approximately 15,000 years old, Wayne said.

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