Maternal effects in birds: effects of nutritional conditions on maternal reproductive effort and offspring performance

The environment experienced by an organism at different life stages can have substantial effects on its phenotype. The environmental conditions the mother encounters can substantially influence her investment in the present reproductive attempt, and the phenotype of her offspring through the so-called maternal effects. Moreover, prenatal and early postnatal conditions experienced by offspring can interact and modulate their life histories. The aim of this thesis is to give new insight into environmentally induced maternal effects and to test the effects of the interaction between pre- and early postnatal conditions on offspring physiology and morphology in a wild-living bird species, the great tit (Parus major). In Chapter one, I investigated how an environmental match / mismatch between the food availability encountered by mothers during egg laying (i.e. prenatal environment) and by nestlings during early growth affected the developmental trajectories of nestlings, testing for a possible role of yolk androgens in mediating potential prenatal maternal effects. I found no evidence that nestlings performed better when experiencing matching nutritional conditions. However, being raised in the original nest by the biological parents (i.e. matching conditions) had positive effects on nestling growth and body mass. I was able to show significant interactive effects of pre- and postnatal food availability on nestling body growth, and significant effects of maternal food availability on nestling body size and mass. However, these effects were not mediated by yolk androgen deposition. The results of this experiment suggest that food-induced maternal effects can have substantial effects on fitness-related traits of the offspring by influencing their efficiency to use nutritional resources. They also highlight the necessity to take multiple environmental factors into account when studying the effects of environmental match / mismatch on offspring phenotype. In Chapter two I assessed how pre- and early postnatal nutritional ...