Docile or hostile?: ‘Domestication’ genes found in foxes

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PARIS, Aug 7, 2018 (BSS/AFP) – A six-decade breeding experiment with
foxes designed to shed light on how wolves became dogs has led to the
discovery of genes that favour tame or aggressive behaviour, scientists said
Monday.

Comparing the sequenced genomes of foxes selected across 50 generations
for their friendliness towards people with another group bred for hostility
uncovered dozens of telltale differences, including one gene in particular,
they reported in the journal Nature Ecology & Evolution.

“We were able to show that a specific gene” — known as SorCS1 — “does
have an effect on behaviour, making foxes more tame,” lead author Anna
Kukekova, an assistant professor at the University of Illinois, told AFP.

“That’s a big result — it’s hard to make that connection,” she said.

The findings are also relevant to human behaviour.

Some of the genetic regions identified, for example, correspond to autism
and bipolar disorders, while others are associated with William-Beuren
syndrome, which causes pathologically outgoing, friendly behaviour.

The backstory to the fox study begins more than half a century ago, when
the origins of animal domestication were poorly understood and hotly
contested.

In 1959, Russian biologist Dmitri Belyaev decided to test his theory that
genes played a more important role than human interaction in the gradual
metamorphosis of wolves into the man’s-best-friend subspecies we call dogs.

At the same time, Nobel laureate Konrad Lorenz, a pioneer in the study of
aggression in animals and humans, argued that new-born wolf puppies raised
with tender loving human care would become docile and domesticated.

Belyaev suspected otherwise, and choose Vulpes vulpes — a.k.a. the red or
silver fox — to make his case.

Russia was full of fox farms which raised and harvested the animals for
their fur, offering the perfect opportunity for a large-scale experiment, he
reasoned.

“Farm-bred foxes were not domesticated,” said Kukekova, an evolutionary
geneticist who began studying the animals 16 years ago. “If you try to touch
them, they show fear and aggression,” much as in the wild.

– Foxes wagging their tails –

Belyaev found a large farm willing to cooperate, and began to
systematically select foxes that exhibited the least stress and fear around
people, repeating the process with each new generation.

“After only 10 generations, they got a few puppies that wagged their tail
just like dogs when they saw people, even when there was no food,” Kukekova
said. “They were just happy to see humans.”

Today, all of the 500 breeding pairs in the tame group are at ease in the
presence of humans, even if they are not as domesticated as dogs.

Around 1970, Belyaev’s team at the Russian Institute of Cytology and
Genetics added a group of foxes, selected for their aggressiveness, and a
third control group with a random mix.

For the new study, Kukekova and two dozen colleagues sequenced the genomes
of 10 foxes from each of the three groups.

“The game changer for us was the development of next-generation sequencing
technology,” she said.

Earlier genetic sweeps yielded chunks of code with dozens or hundreds of
genes, making it impossible to isolate those that mattered.

This time, the researchers pinpointed 103 relevant genetic regions.

Significantly, more than 60 percent of the tame animals — including those
in the control group — shared the same variant of SorCS1. Among the
aggressive foxes, that variant was entirely absent.

The study also revealed that different genes are responsible for very
specific behaviours.

“For example, when foxes greet people by wagging their tail, it seems to
be determined by different genes than those responsible for allowing a human
to touch a fox’s belly,” Kukekova said.

And whether a fox wants to prolong an interaction with a human is governed
by yet another bit of genetic code.

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