Vleck 9801503 Maternal effects describe the non-genetic component of the interaction between mother and offspring characteristics. Eggs are an ideal system in which to study maternal effects because investments made prior to hatching can be measured directly and correlated with subsequent offspring performance. In a population of wild birds studied in 1997, the egg size from which an individual hatched explained a significant amount of the variation in mortality among genetically related individuals during the first two weeks after hatch. The amount of yolk remaining at hatch and yolk testosterone are two maternal effects which may provide a mechanistic understanding of the differences in survival between large and small offspring. In project one the investigator will manipulate the amount of yolk remaining at hatch and explore the effects of these yolk reserves on hatchling growth, development and survival. In project two the investigator will characterize yolk testosterone in eggs and correlate this with chick performance after hatch using a fostering protocol. This fostering design allows for the distinction between pre-hatching and post-hatching maternal effects. Both projects provides for a powerful analysis of variation in maternal effects and the subsequent consequences to offspring performance.
