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Friday, January 27, 2023

brain or muscles? What inspired the creation of modern dog breeds

New York.- When creating modern breeds of dogs, humans shaped the canines into physical patterns that were perfectly suited to perform a wide variety of tasks. The Bernese Mountain Dog has a solid, muscular body capable of pulling heavy loads, while Greyhounds have a lean, streamlined frame, ideal for chasing deer. And the compact Jack Russell Terrier can easily crawl into fox and badger dens.

Now, a large scale study that has just been published in the scientific journal room suggests that behavior, and not just physique, helps qualify those dogs for certain tasks. The study found that breeds that were bred for a similar role—whether herding sheep or shoeing birds—clustered into distinct genetic lineages, each characterized by different combinations of behavioral tendencies.

“A lot of modern breeding has focused on what the dog originally looked like,” he says. Evan McLean, an expert in canine cognition at the University of Arizona, who did not participate in the study. “But before humans started breeding dogs for looks, we were breeding dogs for behavioral traits,” he says.

The study also found that many of the genetic variants that differentiate these lineages from each other seem to regulate brain development, and many appear to predate the formation of modern breeds., Taken together, these two findings suggest that the astonishing diversity of breeds created in modern times was due, at least in part, to the control and preservation of desirable behavioral traits already present in ancient dogs.

The terrier lineage, for example, includes breeds designed to hunt vermin, according to the study.

“The design of all dogs is basically the same, but you have to emphasize certain traits to make them perform certain tasks,” he says. Elaine Ostrander, a specialist in canine genomics at the United States National Human Genome Research Institute. and lead author of the new study. “You adjust a gene up, you adjust a gene down,” he explains.

Bridget von Hold, an evolutionary biologist at Princeton University, Those who were not involved in the study believe the new research is “a real milestone in the field of canine genomics and behavior,” adding that it is “a real encouragement to everyone working in that field.” Will happen.”

Otherwise too, There are still many questions for some scientists; For example, whether humans intentionally set out to create breeds with specific behavioral tendencies. “We don’t have a lot of evidence that there was deliberate selection,” he says. Elinor Carlson, a specialist in canine genomics at the University of Massachusetts, who did not participate in the study.

Still, Carlson praised the study, noting that its findings are consistent with his own research, which also concluded that many of the genetic factors shaping behavior in modern dogs date back to earlier times in dog history.

“The study really takes advantage of the really complex history of dog breeds and those relatively subtle, but real, differences in their behavior to explore how genetics and genetic variations can shape those behavioral traits,” Carlson it is said.

The researchers analyzed the genomes of more than 4,000 canids, including samples from more than 200 different dog breeds, as well as mixed-breed dogs, semi-feral rural dogs, and wild canids such as wolves and coyotes.

Scientists used computer tools to trace the genetic trajectory of ancient dogs until they became, for example, the common herding dog and then their separate breeds, such as the border collie or the German shepherd.

Scientists Trace The Genetic Trajectory Of Ancient Dogs, For Example, The Common Herding Dog And Then Their Separate Breeds, Such As The Border Collie Or The German Shepherd.
Scientists trace the genetic trajectory of ancient dogs, for example, the common herding dog and then their separate breeds, such as the border collie or the German shepherd.

They found that domestic dogs can be divided into 10 different lineages, which generally consist of breeds that were developed to perform similar tasks. For example, the terrier lineage includes breeds designed to hunt vermin, while the hound lineage includes breeds that track by scent rather than highly developed vision.

The researchers point out that while some lineages do have physical characteristics that define them, those characteristics in themselves are not sufficient to explain this classification., “If we think about the lineage of hunter-gatherers, there are breeds that have short or long legs, different tail shapes or different colored coats,” he recalls. Emily Dutro, Postdoctoral Fellow at the National Human Genome Research Institute and also an author on the study, as part of a research team that included James Serpell, Professor Emeritus, College of Veterinary Medicine of Pennsylvania.

To identify the behavioral traits that best defined each breed, researchers analyzed behavioral surveys completed by owners of more than 46,000 purebred dogs.

Although there was a lot of overlap – no one breed has a monopoly on training – overall breeds bred for similar jobs tend to have similar behavioral traits., And each lineage was characterized by its own pattern of behavioral tendencies.

For example, herding dogs, terriers and bloodhounds exhibited relatively high levels of what are known as “non-social phobias”, such as fear of loud noises or foreign objects. The increased sensitivity to environmental stimuli, the researchers say, appears to be useful for all three types of working dog.

Still, the differences were clear: Terriers showed higher levels of “predator detection” than sheepdogs, while shepherds scored higher on trainability.

“There is a lot of significant behavioral diversity among dogs,” says Dutro.

The Bloodhound pedigree scored poorly for trainability, but in their report the researchers note that it is in fact “consistent with the selection of traits beneficial to an independent working style, focused on trend-following rather than searching.” human signal.

To identify the genetic underpinnings of these pedigree-defining traits, the researchers conducted a genome-wide association study, In search of specific genetic variants that were unusually common in certain lineages.

And the vast majority of these lineage-associated variants appeared in parts of DNA that do not code for proteins, but rather control the expression of genes that code for proteins. Many also appear to regulate genes related to brain development.

“When we looked at the genes involved in the differentiation of dog lineages, we saw that a large proportion of those genes are related to neurodevelopment, which suggests that the selection of cognitive and behavioral traits was probably very relevant,” says McLean.

In the study, breeds of sheep were characterized by genetic variants linked to a neurodevelopmental process known as “axon guidance,” which ensures that neurons are connected to each other correctly. Some of these genetic variants are specifically associated with genes related to anxiety and maternal behavior, including pup retrieval in mice.

Scientists say that an as-yet unproven hypothesis is that the drive of lambs to lambs runs along similar neural pathways related to the drive of mother animals to care for their young.

“Seeing these rats, these mothers herding their babies, is like watching a Border Collie herding sheep,” says Ostrander. “Hence the hypothesis that perhaps it is an ancestral behavior that has been co-selected and preserved.”

Regardless, several variants closely related to specific lineages also appeared, at lower levels in other lineages, or even in gray wolves, suggesting that they predate modern breed breeding.

Also, just because there are differences between dog lineages doesn’t mean that a dog’s breed defines its behavior, Carlson explains.

“That doesn’t mean that all retrievers are going to retrieve the ball or that all herders are any different than a retriever. Many dogs do not conform to what we expect based on their breed. And that’s why it’s so much fun to have them as pets.”, explains Carlson.

by Emily Anthes

(Translation by Jaime Arrambide)

new York Times

Conocé Trust Project
World Nation News Desk
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