title: No evidence for parasitism-linked changes in immune function or oxidative physiology over the annual cycle of an avian species.
abstract: Temporally changing environmental conditions occur in most parts of the world and can exert strong pressure on the immune defense of organisms. Seasonality may result in changes in physiological traits over the year, and such changes may be essential for the optimization of defense against infections. Evidence from field and laboratory studies suggest the existence of links between environmental conditions, such as infection risk, and the ability of animals to mount an immune response or to overcome infections; however, the importance of parasites in mediating seasonal change in immune defense is still debated. In this study, we test the hypothesis that seasonal change in immune function and connected physiological traits is related to parasite infection. We sampled captive house sparrows (Passer domesticus) once every 2 mo over 14 mo and compared the annual variation in 12 measures of condition, immune function, antioxidant status, and oxidative damage among birds naturally infested with coccidians or medicated against these parasites. We found significant variation in 10 of 12 traits over the year. However, we found little support for parasite-mediated change in immune function and oxidative status in captive house sparrows. Of the 12 measures, only one was slightly affected by parasite treatment. In support of the absence of any effect of coccidians on the annual profile of the condition and physiological traits, we found no consistent relationships between the intensity of infestation and these response variables over the year. Our results show that chronic coccidian infections have limited effect on the seasonal changing of physiological traits and that the patterns of these measures are probably more affected by acute infection and/or virulent parasite strains.
authors.affiliation: MTA-DE "Lendület" Behavioral Ecology Research Group, Department of Evolutionary Zoology and Human Biology, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary; 2Evolutionary Ecology Group, Hungarian Department of Biology and Ecology, Babeş-Bolyai University, Clinicilor Street 5-7, RO-400006 Cluj Napoca, Romania; 3Department of Molecular Biology and Biotechnology, Babeş-Bolyai University, Clinicilor Street 5-7, RO-400006 Cluj Napoca, Romania; 4Research and Innovation Portfolio, University of Toronto, Toronto, Ontario, Canada; 5Animal Ecology Group, Center for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands.
authors.forename: Péter L
authors.initials: PL
authors.lastname: Pap
authors.forename: Alina
authors.initials: A
authors.lastname: Sesarman
authors.forename: Csongor I
authors.initials: CI
authors.lastname: Vágási
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Buehler
authors.forename: Laura
authors.initials: L
authors.lastname: Pătraş
authors.forename: Maaike A
authors.initials: MA
authors.lastname: Versteegh
authors.forename: Manuela
authors.initials: M
authors.lastname: Banciu
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000276:immunology* / Q000469:parasitology; D005260:Female; D006403:Hematologic Tests / Q000662:veterinary; D007113:Immunity, Innate; D007549:Isospora / Q000302:isolation & purification; D021865:Isosporiasis / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D008297:Male; D010084:Oxidation-Reduction; D059208:Parasite Load / Q000662:veterinary; D012383:Romania; D012621:Seasons; D046370:Sparrows