Rapid decline of prenatal maternal effects with age is independent of postnatal environment in a precocial bird.

The article investigates how prenatal maternal effects on offspring body mass in Japanese quail (Coturnix japonica) change with age and whether these effects interact with postnatal environmental quality, specifically diet. Using controlled breeding with known pedigrees and experimental manipulation of offspring diet (poor vs. standard quality), the study found strong maternal genetic effects on body mass at hatching, primarily driven by variation in egg mass. However, these prenatal maternal effects rapidly declined with age and were not influenced by the quality of the postnatal diet. Instead, additive genetic and residual variances increased during growth, with residual variance notably higher under the poor diet. The findings suggest that prenatal maternal effects on early body mass are largely mediated by egg size and are quickly replaced by offspring genetic and environmental factors as development proceeds, with no evidence for maternal effect by environment interactions in this precocial bird species.