Poor developmental conditions decrease adult body size and egg size, but not egg laying rate and survival throughout adulthood: A long-term experiment in a precocial bird

The quality of the environment during individual development is generally
considered to have long-lasting effects on performance in adulthood, but
this is mainly based on observational studies that cannot pinpoint the
causal pathways behind such long-term effects. In this study, we performed
a randomized controlled trial to test for causal effects of a poor rearing
diet on performance in growth, reproduction, and survival, over the
complete life course of female Japanese quail (Coturnix japonica). All
individuals were housed under standardized conditions as adults, to allow
separating effects of the developmental environment from effects of the
adult environment. The poor rearing diet led to a dramatically reduced
growth, which delayed the onset of reproduction, and resulted in a reduced
body size throughout adulthood, as compared to a standard rearing diet.
While there were no detectable effects on age-specific egg laying rate and
survival, despite strong senescence in these fitness traits, females
reared with the poor diet did lay smaller eggs. Hence, although there was
no effect of the poor developmental environment on female laying rate and
survival per se, the developmental environment of a mother did affect her
adult size and the environment she provides for her offspring during
embryonic development. We suggest that the effects on female adult size
and egg size may cause ‘silver spoon’ effects in the wild, if larger size
provides an advantage in competition over resources. However, we cannot
rule out that smaller size would lead to lower food requirements, thereby
acting as a ‘predictive adaptive response’ to a poor environment.