Extending the ecology of fear: Parasite-mediated sexual selection drives host response to parasites

The ‘ecology of fear’ describes the negative effects natural enemies have on potential victims even when those victims are not consumed or infected. Although recent work has demonstrated parasites have non-consumptive effects (NCE) on potential hosts, how these effects vary within host populations is not well understood. We investigated how NCE vary based on host risk of infection and relative cost of infection by measuring the metabolic rate (MR) of naive Drosophila nigrospiracula exposed to an ectoparasite, Macrocheles subbadius. We tested two mutually exclusive hypotheses: 1) asymmetrical costs of infection drive adaptions for stronger responses to parasite exposure; or 2) asymmetrical risks of infection drive adaptions for stronger responses to parasite exposure. In this system, male flies have higher costs of infection relative to female flies due to parasite-mediated sexual selection; similarly, virgin females experience higher costs of infection relative to mated females. Risk of...