Cellular immune response, stress resistance and competitiveness in nestling great tits in relation to maternally transmitted carotenoids

Authors: BERTHOULY, ANNE; HELFENSTEIN, FABRICE; RICHNER, HEINZ

Source: Functional Ecology, Volume 21, Number 2, April 2007 , pp. 335-343(9)

Publisher: Wiley-Blackwell

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Abstract:

Summary

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Egg yolks contain carotenoids that protect biological molecules against free-radical damage and promote maturation of the immune system. Availability of carotenoids to birds is often limited. Trade-offs can thus arise in the allocation of carotenoids to different physiological functions, and mothers may influence the immunocompetence of nestlings by modulating the transfer of carotenoid to the yolk.

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In the great tit Parus major, we experimentally manipulated the dietary supply of carotenoid to mothers, and partially cross-fostered hatchlings to investigate the effect of an increased availability of carotenoids during egg laying on immunocompetence of nestlings.

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In addition, we infested half of the nests with hen fleas Ceratophyllus gallinae to investigate the relationship between carotenoid availability, resistance to ectoparasites and immunocompetence.

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We found that the procedure of cross-fostering can reduce the immune response of nestlings, but this effect can be compensated by the maternally transferred carotenoids. Cross-fostered nestlings of carotenoid-supplemented females show a similar immune response to non-cross-fostered nestlings, while cross-fostered nestlings of control females mounted a weaker cell-mediated immune response. This suggests that yolk carotenoids may help nestlings to cope with stress, for example the one generated by cross-fostering and/or they may enhance nestling competitiveness.

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There was no statistically significant interaction between parasite and carotenoid treatments, as would be expected if carotenoids helped nestlings to fight parasites. Under parasite pressure, however, lighter nestlings raised a lower immune response, while the immune response was only weakly correlated with body mass in uninfested nests.

Functional Ecology (2007) 21, 335-343

doi: 10.1111/j.1365-2435.2006.01236.x

Keywords: ectoparasite resistance; maternal effects; nestling competition; stress; yolk carotenoids

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2435.2006.01236.x

Publication date: 2007-04-01