Wolves encouraged by parasites are more likely to lead packs: study

leader of the pack? A parasite could make gray wolves in Yellowstone National Park take more risks, research suggests.

Wolves infected with a common parasite are much more likely to become the leaders of their pack, according to a new study, suggesting the brain-dwelling invader encourages its host to take more risks.

The unicellular parasite Toxoplasma gondii reproduces sexually only in cats, but can infect all warm-blooded animals.

It is estimated that between 30 and 50 percent of people worldwide are infected with the parasite, which remains as dormant tissue cysts for life. However, people with a healthy immune system rarely have symptoms.

While some studies report an association between people who have the parasite in their brains and increased risk-taking, other research has disputed these findings, and no definitive link has been demonstrated.

The new study, published in the journal communication biology on Thursday used 26 years of data on gray wolves living in Yellowstone National Park in the United States to study how the parasite might affect their behavior.

The Yellowstone Wolf Project researchers analyzed blood samples from nearly 230 wolves and 62 cougars – the big cats are known carriers of the parasite.

They found that infected wolves were more likely to encroach deeper into cougar territory than uninfected wolves.

Infected wolves were also 11 times more likely to leave their packs than wolves without the parasite, according to the study, indicating greater risk-taking.

And an infected wolf is up to 46 times more likely to become the pack leader, the researchers estimated, adding that the role is usually filled by more aggressive animals.

Study co-author Kira Cassidy told AFP that “being braver isn’t necessarily a bad thing,” but it “can reduce the survival of the bravest animals because they may be more likely to make decisions that put them at risk.” “.

“Wolves don’t have the survival space to take too many more risks than they already do.”

Cassidy said it was only the second study of the effect of T. gondii on a wild animal, after research last year found infected hyena pups were more likely to get closer to and be killed by lions in Kenya than infected hyena pups.

Laboratory studies have also found that rodents with the parasite lose their instinctive fear of cats, driving them into the hands of the only host in which T. gondii can reproduce.

William Sullivan, a professor of pharmacology and toxicology at Indiana University School of Medicine who has studied T.gondii for more than 25 years, called the wolf paper “a rare gem.”

However, he warned that such an observational study could not show causality.

“A wolf that’s a born risk taker is more likely to venture into cougar territory and become infected with Toxoplasma,” he said.

But “if the results are correct, they suggest that we may be underestimating the impact of Toxoplasma on ecosystems around the world,” he added.

what about people

“That’s the million-dollar question,” Sullivan said, adding that “nobody knows for sure and the literature is mixed”.

Ajai Vyas, a T. gondii expert at Nanyang Technological University in Singapore, warned against concluding that infection could increase risk-taking in humans.

“There is much in human behavior that is different from that of other animals,” he told AFP.

Humans often become infected with T. gondii by eating undercooked meat — or through their pet cat, particularly when they clean their litter boxes.

In some cases, particularly in people with compromised immune systems, T. gondii can lead to toxoplasmosis, a disease that can cause brain and eye damage.

More information:
Connor J. Meyer et al, Parasitic infection increases risk-taking in a social carnivore with an intermediate host, communication biology (2022). DOI: 10.1038/s42003-022-04122-0

© 2022 AFP

Citation: Wolves encouraged by parasites are more likely to lead packs: study (2022, November 27), retrieved November 27, 2022 from https://phys.org/news/2022-11-wolves-emboldened-parasite.html

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