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Genetic patterns of world's farmed, domesticated foxes revealed via
historical deep-dive
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Credit: Anna Kukekova, University of Illinois Urbana-Champaign
Domesticated animals play a prominent role in our society, with two-
thirds of American families enjoying the companionship of pets and
many others relying on animal products for their nutritional needs.
But the process of domestication remains a bit of a mystery.
Convincing wild animals they are safe enough to coexist and mate in
enclosures and in close proximity to humans and other animals is no
small feat. What does it take behaviorally and genetically for that to
happen?
For the most part, the animals we've domesticated have been docile for
so long that there's no easy way to go back and study the transition
from wild to tame. A notable exception is the domestication of red
foxes—raised in captivity for their fur—starting in 1896 on Canada's
Prince Edward Island. A team from the University of Illinois Urbana-
Champaign has traced the process from its beginnings on the island to
captive fox populations around the world, including some still in
operation today.
The work is published in the _Journal of Heredity_.
"We have the historical documents, we have genetic information about
wild fox populations all over the world, and we obtained samples from
foxes bred in North America and Eurasia. So we can really dig into the
question of how foxes were domesticated and how their genetics were
shaped by geography and time," said lead study author Halie Rando, an
assistant professor at Smith College who completed her doctoral
research in the Illinois Informatics Institute, now in the School of
Information Sciences, at Illinois.
Rando, along with Illinois animal sciences professor Anna Kukekova and
their collaborators, analyzed new and previously published
mitochondrial DNA data from wild fox populations and from 10 captive
populations in North America and Eurasia, including the site of the
famous Russian fox domestication experiment. They then cross-
referenced historical records related to the intercontinental trade of
foxes, changing fur demand and farm sizes, and breeding practices.
Together, the data allowed them to determine the geographical origins
of farmed foxes worldwide and understand the role of genetic diversity
in the domestication process.
"When we do population genetics research, we're able to uncover
history forensically," Rando said. "Looking at signatures that are in
present populations, we can make inferences about the past."
Early fox farmers were motivated by the demand for the silver variant
of red foxes. Trying to trap rare silver foxes from the wild was
unreliable and difficult, but breeding them in captivity had its own
challenges.
"The foxes were very hard to breed on the farms because they would get
really stressed out and die or kill their offspring. It took a long
time for them to figure out how to set up the breeding enclosures to
reduce stress. Along the way, they were selecting for individuals that
were better suited to the farm environment," Rando said. "They also
managed to select for the silver fur color. Even without knowing any
genetics, they figured out how to crack the code."
After that, the industry boomed, with Canadian foxes being exported
across the world. The genetic analysis showed that every captive
population the researchers surveyed—even those in Eurasia—originated
from wild North American foxes. In fact, there were no traces of
genetic markers from Eurasian wild fox populations, suggesting any
attempts at domesticating local populations were abandoned or
overtaken by North American genetics.
"This study helps to answer questions researchers have asked for years
about the geographic origin and genetic background of these fox
populations," Kukekova said. "Furthermore, some farm foxes may have
mixed with native foxes through release events over the years in
different locations. Occasionally, unexpected gene signatures show up
in native populations, so our study may help to explain where they're
coming from."
World War II interrupted demand, and the industry never recovered in
North America. In the USSR, however, fox farms quickly rebounded,
aided by the government-supported fur industry.
Overall, the genetic pattern reflects the more stable history of
breeding in Eurasia. Although all the farmed foxes in the study were
found to originate from North American wild foxes, populations in
Eurasia were more genetically diverse, with greater representation
from Alaskan and western U.S. genotypes in addition to common
genotypes from Eastern Canada.
"Some gene signatures were very rare and found only in certain
Eurasian farm populations," Rando said. "The presence of these rare
signatures, along with more diversity overall in Europe, could be due
to more stable population sizes there after World War II, whereas
those rare types may have been lost when North American farms
collapsed."
The study also sheds light on the famous Russian Farm Fox experiment,
started in 1959 at the Institute of Cytology and Genetics (ICG) in
Novosibirsk. The study originated with the selection of farm-bred
foxes that showed the least avoidant behaviors around humans. Through
successive generations, scientists selectively bred foxes with tame
behaviors, eventually resulting in foxes as friendly as the family
dog.
The current study sampled that population and analyzed it along with
the others, finding no unique genetic origins for the Russian foxes.
To Rando, this suggests that farm-bred foxes may have the same
underlying capacity to develop friendly behaviors.
"I'd say we pretty conclusively demonstrated that the foxes in
Novosibirsk are not meaningfully different from other farm-bred foxes
in terms of their genetic origins. We also found that the populations
in Novosibirsk were among the most genetically diverse captive
populations, likely due to their meticulous pedigree records and
carefully planned breeding," she said.
Kukekova added, "It's informative to know that this one successful
endeavor in Prince Edward Island really had a huge effect on modern
populations that persists to this day. The model can help us study
domestication broadly and find gene networks leading to tame behavior,
which is something that humans have been interested in for a very long
time."
**More information:** Halie M Rando et al, Missing history of a modern
domesticate: Historical demographics and genetic diversity in farm-
bred red fox populations, _Journal of Heredity_ (2024). DOI:
10.1093/jhered/esae022
**Citation** : Genetic patterns of world's farmed, domesticated foxes
revealed via historical deep-dive (2024, July 1) retrieved 3 July 2024
from https://phys.org/news/2024-07-genetic-patterns-world-farmed-
domesticated.html
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