Morphological plasticity reduces the effect of poor developmental conditions on fledging age in mourning doves.

Developmental plasticity can be integral in adapting organisms to the environment experienced during growth. Adaptive plastic responses may be especially important in prioritizing development in response to stress during ontogeny. To evaluate this, I examined how developmental conditions for mourning doves related to early growth and how this affected fledging age, an important life-history transition for birds. The life history of mourning doves is consistent with strong selective pressure to minimize fledging age. Therefore, I predicted that in the face of nutritional stress associated with experimental brood-size increases, young would prioritize growth to structures that promote early fledging to reduce the effect of slowed overall growth on fledging age. Increasing brood size slowed overall structural growth of nestlings and affected the relative allocation of growth among different body parts. Total wing area was the best predictor of fledging age and individuals from larger broods had larger wings relative to overall body size. Although nestlings from larger broods fledged at later ages owing to slower overall growth, prioritization of wing growth reduced this effect by an estimated 1.6 days relative to the delay if plasticity among body parts had not occurred. This was an 11 per cent reduction in the predicted developmental time it took to reach this important life-history transition. Results demonstrate that preferential allocation to wing growth can affect the timing of this life-history transition and that morphological plasticity during development can have adaptive near-term effects during avian development.