Cryptic consequences of parasitism

Parasites can have a range of negative consequences on individuals and populations. We explored mechanisms by which parasitic worms affect the fitness of Grants gazelles (Nanger granti). To do this, we first assessed how parasites influenced time allocation to competing behaviors in female gazelles. Second, we investigated when parasites are more likely to impose costs on individuals with lower levels of genetic diversity, or heterozygosity. We showed that parasites can affect the time female gazelles allocate to foraging versus vigilance, which may have important implications for individual predation risk. We also showed that less genetically diverse animals may suffer from higher parasite burdens but only under certain environmental conditions and for certain individuals. Overall, our work demonstrates that parasites can exert effects on hosts via cryptic mechanisms that are manifested through host behavior or that occur only during specific times or for specific individuals.