Parasite Prevalence Depends on Female Preference: Integrating
Parasite-Mediated Sexual Selection and Infectious Disease Dynamics
Abstract
If ornament quality advertises heritable resistance to a directly
transmitted parasite, female preference for males with higher quality
ornaments could reduce parasite prevalence via two pathways. Preference
for, and thus more contact with, resistant males should: 1) change
parasite transmission opportunities; and 2) increase offspring parasite
resistance. Here, we used data and parameterized a SIR model to test the
hypothesis that, across populations of guppies (Poecilia
reticulata), the strength of female preference negatively correlates
with prevalence of directly transmitted gyrodactylids. Female guppies
exhibit between-population variation in preference for males with larger
orange ornaments that are heritable and forecast resistance. Using 89
prevalence estimates from 10 populations, and controlling for ecological
covariates, we found that populations with significant female preference
had lower prevalence than those without. Our theoretical model inferred
that preference affects prevalence largely by affecting offspring
parasite resistance. Female preference can thus drive the dynamics of
ordinary infectious diseases.