Life-history theory predicts that rapid growth comes at a cost to offspring quality and adult longevity. However, trade-offs have been examined primarily based on proximate variation within species rather than evolved differences across species. Evolved differences are important to examine because species may co-evolve mechanisms to reduce long-term costs of rapid growth. For example, trade-offs associated with fast growth and short development time might be expressed in ephemeral traits because costs associated with these traits are paid for only a short duration. We explored this idea using nestling body feathers, an ephemeral trait, and examined whether shorter development time yielded lower quality feathers. We found a strong trade-off whereby nestlings that spend more time in the nest produced higher quality plumage across 123 temperate and tropical species. Using a subset of these species (n=67), we found that plumage quality was lower in species with higher rates of nest predation, which favors rapid nestling growth and short development times. Our results suggest that evolution of more rapid growth may co-evolve with other mechanisms whereby long-term costs are reduced by shifting costs of allocational trade-offs to ephemeral traits that are short-lived.
