Immunocompetence of nestling great tits in relation to rearing environment and parentage

Abstract

Theoretical models of host^parasite coevolution assume a partially genetic basis to the variability in susceptibility to parasites among hosts, for instance as a result of genetic variation in immune function. However, few empirical data exist for free-living vertebrate hosts to support this presumption. In a crossfostering experiment with nestling great tits, by comparing nestlings of the same origin we investigated (i) the variance in host resistance against an ectoparasite due to a common genetic origin, (ii) the e¡ect of ectoparasite infestation on cell-mediated immunity and (iii) the variance in cell-mediated immunity due to a common genetic origin. Ectoparasitic hen £eas can impair the growth of nestling great tits and nestling growth was therefore taken as a measure of host susceptibility. A common origin did not account for a signi¢cant part of the variation in host susceptibility to £eas. There was no signi¢cant overall e¡ect of £eas on nestling growth or cell-mediated immunity, as assessed by a cutaneous hypersensitivity response. A common rearing environment explained a signi¢cant part of the variation in cell-mediated immunity among nestlings, mainly through its e¡ect on nestling body mass. The variation in cellmediated immunity was also related to a common origin. However, the origin-related variation in body mass did not account for the origin-related di¡erences in cell-mediated immunity. The results of the present study thus suggest heritable variation in cell-mediated immunity among nestling great tits.

Sex-specific development of cell-mediated immunity under experimentally altered rearing conditions in blue tit nestlings

“…Donor nestlings from enlarged broods were included in all analyses as (i) there was no evidence that they were disadvantaged by rearing in a non-natal environment (mixed model ANOVA with nest ID as a random factor and nestling origin as a fixed factor, donor versus natal nestlings (meanGs.e. ); body mass on day 14 post-hatching: 10.84G0.16 versus 10.70G0.14, (c) Assessment of cell-mediated immunity T-cell-mediated immune function of nestlings was assessed as a response to phytohaemagglutinin (PHA, Sigma Chemicals) injection, which is a standard test used in avian studies (Lochmiller et al 1993;Brinkhof et al 1999;Tella et al 2000). PHA is a bean extract that has a mitogenic effect on T lymphocytes, and its inoculation stimulates dense accumulation of lymphocytes (Goto et al 1978).…”

Lifetime reproductive success in seabirds: interindividual differences and implications for conservation

“…Before confronting a sudden breakdown in immunocompetence of endangered seabirds, we should try to get baseline levels on populations little affected by human-induced changes yet. Sudden mass mor-LIFETIME REPRODUCTION IN SEABIRDS 11 From studies by Tella et al (2000), Brinkhof et al (1999), Soler et al (2003) and Saino et al (1997). talities in the future may be associated with changes in immune defenses if we know what to expect. As a general point, the neglect until present of the immune system in ecological and conservation studies (Sheldon and Verhulst, 1996) should be replaced by a fuller consideration of its importance for life histories and population dynamics.…”

Transgenerational body size effects caused by early developmental stress in zebra finches

“…Experimental manipulations of brood size in birds have been a powerful tool to affect nestling condition through developmental stress because birds raised in enlarged broods have reduced growth, condition (Tinbergen & Boerlijst 1990;Brinkhof et al 1999;Naguib et al 2004), survival (de Kogel 1997 and recruitment rates after migration (Gustafsson & Sutherland 1988;Smith et al 1989). However, in contrast to mammals (Huck et al 1987) and insects (Fox & Mousseau 1998), in birds the extent to which these effects of developmental stress on offspring are projected into future generations is still not known.…”