title: Fitness costs of disrupting circadian rhythms in malaria parasites.
abstract: Circadian biology assumes that biological rhythms maximize fitness by enabling organisms to coordinate with their environment. Despite circadian clocks being such a widespread phenomenon, demonstrating the fitness benefits of temporal coordination is challenging and such studies are rare. Here, we tested the consequences--for parasites--of being temporally mismatched to host circadian rhythms using the rodent malaria parasite, Plasmodium chabaudi. The cyclical nature of malaria infections is well known, as the cell cycles across parasite species last a multiple of approximately 24 h, but the evolutionary explanations for periodicity are poorly understood. We demonstrate that perturbation of parasite rhythms results in a twofold cost to the production of replicating and transmission stages. Thus, synchronization with host rhythms influences in-host survival and between-host transmission potential, revealing a role for circadian rhythms in the evolution of host-parasite interactions. More generally, our results provide a demonstration of the adaptive value of circadian rhythms and the utility of using an evolutionary framework to understand parasite traits.
authors.affiliation: Institute of Evolution, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3JT, UK.
authors.forename: Aidan J
authors.initials: AJ
authors.lastname: O'Donnell
authors.forename: Petra
authors.initials: P
authors.lastname: Schneider
authors.forename: Harriet G
authors.initials: HG
authors.lastname: McWatters
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Reece
mesh_terms: D000818:Animals; D005075:Biological Evolution; D057906:Circadian Clocks; D002940:Circadian Rhythm; D056084:Genetic Fitness; D006790:Host-Parasite Interactions; D008027:Light; D008288:Malaria / Q000469:parasitology / Q000635:transmission; D008297:Male; D051379:Mice; D017440:Photoperiod; D016788:Plasmodium chabaudi / Q000502:physiology* / Q000528:radiation effects*; D012098:Reproduction; D012376:Rodent Diseases / Q000469:parasitology* / Q000635:transmission