Evidence for parasite-mediated sexual selection has been found in many species that use visual ornaments to attract females.
However, in many animals, variation in female responses to scents of parasitized males suggests that parasitic infections
might also affect information conveyed by pheromones (i.e., chemical ornaments). Thus, pheromones might also function in parasite-mediated
sexual selection. We show here that female lizards
Psammodromus algirus responded differently to femoral gland secretions of males according to the parasite load and health of these males. Scents
of healthier males elicited more tongue flicks (a chemosensory behavior) by females, suggesting that these scents were more
attractive. Chemical analyses showed that parasite load and the T-cell-mediated immune response were related to the variability
in the proportions of some lipids in secretions of males. Further trials testing the chemosensory responses of females to
chemical standards indicated that females actually discriminated the chemicals related to males’ health from other chemicals
found in secretions. We suggest that these chemical ornaments may provide reliable information on the health and degree of
parasitic infection of a male.
Keywords Lizards - Femoral glands - Condition-dependent signaling - Sexual selection - Parasites - Immune response - Chemical signals
Communicated by W. Cooper