Proceedings of the Royal Society B: Biological Sciences DOI： 10.1098/rspb.2011.0842
Ontogenetic immune challenges shape adult personality in mallard ducks
Butler, Michael W.; Toomey, Matthew B.; McGraw, Kevin J.; Rowe, Melissah
Consistent individual differences in behaviour are widespread in animals, but the proximate mechanisms driving these differencesremain largely unresolved. Parasitism and immune challenges are hypothesized to shape the expression of animal personalitytraits, but few studies have examined the influence of neonatal immune status on the development of adult personality. Weexamined how non-pathogenic immune challenges, administered at different stages of development, affected two common measuresof personality, activity and exploratory behaviour, as well as colour-dependent novel object exploration in adult male mallardducks (Anas platyrhynchos). We found that individuals that were immune-challenged during the middle (immediately following the completion of somaticgrowth) and late (during the acquisition of nuptial plumage) stages of development were more active in novel environmentsas adults relative to developmentally unchallenged birds or those challenged at an earlier developmental time point. Additionally,individuals challenged during the middle stage of development preferred orange and avoided red objects more than those thatwere not immune-challenged during development. Our results demonstrate that, in accordance with our predictions, early-lifeimmune system perturbations alter the expression of personality traits later in life, emphasizing the role that developmentalplasticity plays in shaping adult personality, and lending support to recent theoretical models that suggest that parasitepressure may play an important role in animal personality development.