Originally aired on August 2, 2023

The Wondros episode focused on new research examining how a common parasite called Toxoplasma gondii (Toxo) affects the behavior of wolves in Yellowstone National Park. Jesse and Priscilla interviewed two scientists, Connor Meyer and Kira Cassidy, who conducted the study.

The researchers found that wolves infected with Toxo were more likely to disperse from their packs and become leaders of new packs compared to uninfected wolves. They theorize the parasite may increase boldness, helping infected wolves take more risks to find mates and start new packs. This benefits the parasite’s goal of reproducing and spreading to new hosts like mountain lions that roam the Yellowstone area.

To examine the parasite’s impact, the researchers tested blood samples from wolves in Yellowstone going back over 20 years. Around 25-40% of the wolves had Toxo antibodies, indicating past exposure. The parasite likely spreads when wolves ingest infected mountain lion scat while exploring territorial boundaries.

While Toxo may give infected wolves a behavioral edge for leadership, the researchers noted it could also increase risky behaviors that lower survival. Wolves dispersing to new packs face many threats alone before finding a mate. Still, the parasite seems to manipulate host behavior to further its spread, an evolutionary strategy seen in other species too.

The researchers plan to continue studying how Toxo may interact with wolf personality, relationships, and culture learned from pack mates. Their work sheds light on how a common parasite affects animal behavior and the ecosystem.

How does a common parasite change wolf behavior in Yellowstone?

• Researchers found the Toxoplasma gondii (Toxo) parasite makes wolves more likely to disperse and become leaders of new packs.
• They theorize Toxo increases boldness and risk-taking, helping wolves find mates and reproduce.
• Testing wolf blood samples, 25-40% showed past Toxo exposure. It spreads via mountain lion scat in territory.
• While aiding leadership, Toxo may also lower survival through risky dispersal from packs.
• The parasite manipulates host behavior to spread further, a common evolutionary strategy.
• Researchers will continue studying Toxo’s impact on wolf personality, bonds, and culture.