Biology Faculty Articles

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Nature Communications





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Toxoplasma gondii is hypothesized to manipulate the behavior of warm-blooded hosts to promote trophic transmission into the parasite’s definitive feline hosts. A key prediction of this hypothesis is that T. gondii infections of non-feline hosts are associated with costly behavior toward T. gondii’s definitive hosts; however, this effect has not been documented in any of the parasite’s diverse wild hosts during naturally occurring interactions with felines. Here, three decades of field observations reveal that T. gondii-infected hyena cubs approach lions more closely than uninfected peers and have higher rates of lion mortality. We discuss these results in light of 1) the possibility that hyena boldness represents an extended phenotype of the parasite, and 2) alternative scenarios in which T. gondii has not undergone selection to manipulate behavior in host hyenas. Both cases remain plausible and have important ramifications for T. gondii’s impacts on host behavior and fitness in the wild.


We thank the Kenyan National Commission for Science, Technology, and Innovation, the Naboisho Conservancy, the Narok County Government, the Kenya Wildlife Service (KWS) and Brian Heath for permission to conduct research in the Mara ecosystem. We also thank Chiara Bowen and Nichole Grosjean for lab assistance, Samantha Gregg, Katie Keyser, Leah McTigue, and Abigail Thiemkey for assistance extracting distances between lions and hyenas, the NSF-BEACON center for the Study of Evolution in Action for funding, the Mara Hyena Project field crew, and the residents of the Mara ecosystem for their direct and indirect support of long-term field research in their backyard. We thank Joy Baldwin for providing the lion illustration and Mark Bellncula and Page E. Van Meter for providing the hyena silhouettes seen in Fig. 1. We thank members of the Getty and Holekamp labs for their feedback on this project and paper. This material is based in part upon work supported by the National Science Foundation under Cooperative Agreement No. DBI-0939454. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Sample collection and behavioral data collection were supported by NSF grants IOS1755089 and OISE1853934. Z.M.L. was funded by the Morris Animal Foundation grant D19ZO-411.

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© The Author(s) 2021

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Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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