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Toxoplasma gondii, a multi-host protozoan parasite capable of infecting any warm-blooded species, might be the reason why some wolves can take more significant risks and establish themselves as leaders of packs. A new study published on the Nature website analysed behavioural, spatial, and serological data of wolves in the Yellowstone National Park, U.S., over 26 years to come to the conclusion that wolves infected by the microorganism changed their behaviour to take greater risks – they are more likely to disperse and become pack leaders than wolves who do not carry the infection. The structure of wolf packs is such that these behavioural changes can possibly lead to a feedback loop, enhancing risk-taking across members of the pack.
Yellowstone National Park has a diverse population of carnivores, including grey wolves (Canis lupus) and cougars (Puma concolor), which are intermediate and definitive hosts of T. gondii, respectively. In the study, wolf territory overlap with areas of high cougar density was an important factor that predicted the infection.
Once an intermediate host is exposed, the infection spreads from the intestinal lining to form cysts in the brain and muscle tissue, causing acute toxoplasmosis (infection with the parasite). The infection doesn’t show clinical symptoms in individuals with a robust immune system, but they have a chronic lifetime infection due to the presence of cysts. Chronic infections, even in healthy individuals, can lead to increased dopamine and testosterone production. These hormones are associated with increased aggression and risk-taking behaviour. Scientists believe that because of the overlap of the seroprevalence of T. gondii in grey wolves with cougars, the former are likely contracting the parasite either through direct contact with cougars or through their shed oocysts, and not through consumption of other intermediate host species.
Previously, infection with the parasite T. gondii has been linked to increased risk-taking in rodents, chimpanzees, and hyenas.
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Published - November 30, 2022 02:12 pm IST