Migratory behaviour predicts greater parasite diversity in ungulates

Area of Science:

• Ecology and Evolutionary Biology
• Parasitology
• Wildlife Health

Background:

• Long-distance animal movements influence parasite exposure, with potential benefits (habitat escape) and risks (increased exposure).
• The impact of host movement strategies on parasite diversity across multiple host taxa remains poorly understood.
• Previous studies focused on single-host/single-parasite systems, limiting cross-species understanding of movement-parasite dynamics.

Purpose of the Study:

• To investigate how different host movement strategies (migration, nomadism, residency) affect parasite species richness and prevalence across ungulate taxa.
• To test the 'environmental tracking' hypothesis and compare it with alternative hypotheses like migratory escape and culling.

Main Methods:

• Comparative analysis of parasite communities from 93 species of migratory, nomadic, and resident ungulates.
• Statistical modeling to account for factors influencing parasite diversity, including body size and host geographical range.

Main Results:

• Migratory ungulates exhibit significantly higher parasite species richness compared to resident and nomadic species, even after controlling for covariates.
• Evidence supports the 'environmental tracking' hypothesis: migration may allow parasites to access favorable transmission environments throughout the year.
• Social aggregation and large group sizes associated with migration may also contribute to increased parasite infection risk for migrants.

Conclusions:

• Long-distance host movement, particularly migration, is mechanistically linked to increased parasite species richness at the species level.
• The 'environmental tracking' hypothesis provides a strong explanation for higher parasite diversity in migratory species.
• Findings can inform predictions about how climate change and altered animal movements may impact wildlife parasitism.