title: Immune function and survival of great tit nestlings in relation to growth conditions.
abstract: Life history theory predicts a trade-off between number and quality of offspring. Reduced quality with increasing brood size may arise from a decrease in body condition or in immunocompetence that would be important in fighting off virulent parasites by immunologically naive offspring. We tested the effect of rearing conditions on immune function of nestling great tits (Parus major) by reducing or increasing broods by two hatchlings. In the middle of the nestling period (on day 8), nestlings from enlarged broods developed lower T cell responses [as measured from the cutaneous swelling reaction to injection with phytohaemagglutinin (PHA)] and tended to have lower total leukocyte and lymphocyte concentrations in their peripheral blood than nestlings from reduced broods. Brood size manipulation affected the PHA response of nestlings most strongly in small clutches, suggesting that nestling immune function was dependent on their parents' condition, as estimated by original clutch size. Intra-brood differences in nestling mortality were unrelated to immune parameters, but nestlings in broods without mortality had a stronger PHA response, higher concentration of lymphocytes and higher body mass on day 15 than nestlings in broods with mortality. These results support the prediction that the immune function of altricial birds is affected by rearing conditions, and that growth and immune parameters are related to inter-brood differences in nestling survival.
authors.affiliation: Institute of Zoology and Botany, Riia 181, EE-51014 Tartu, Estonia, , , , , , EE.
authors.forename: P
authors.initials: P
authors.lastname: Hõrak
authors.affiliation: Institute of Zoology and Hydrobiology, Tartu University, Vanemuise 46, EE-51014 Tartu, Estonia, , , , , , EE.
authors.forename: L
authors.initials: L
authors.lastname: Tegelmann
authors.affiliation: Institute of Zoology and Hydrobiology, Tartu University, Vanemuise 46, EE-51014 Tartu, Estonia, , , , , , EE.
authors.forename: Indrek
authors.initials: I
authors.lastname: Ots
authors.affiliation: Laboratorie d'Ecologie, CRNS URA 258, Université Pierre et Marie Curie, Bât. A, 7ème étage, 7 quai St. Bernard, Case 237, F-75252 Paris Cedex 05, France, , , , , , FR.
authors.forename: Anders Pape
authors.initials: AP
authors.lastname: Møller
keywords: Key words Brood size manipulation; Nestling immunocompetence; Nestling survival; Parus major; Phytohaemagglutinin test