Abstract

Avian embryos undergo extremely rapid development over a relatively short
period of time, and so are likely to suffer high levels of oxidative damage
unless this is mitigated by sufficient maternal allocation of appropriate antioxidants.
At a species level, it is therefore predicted that antioxidants should
be allocated to eggs according to the rate of embryonic growth, such that eggs
containing embryos that grow faster are furnished with higher antioxidant
levels, independent of egg size. We tested this prediction for three potentially
important classes of dietary-derived yolk antioxidants: carotenoids, vitamin E
and vitamin A. Across species,we found positive relationships between embryonic
growth rate and total yolk levels of each of the three antioxidant classes.
Moreover, there were consistent differences in antioxidant provision between
pairs of species that share a common initial egg mass yet have differing rates
of embryonic growth, such that the eggs of the faster-developing species have
higher levels of carotenoids and vitamin E. These results may explain the
marked interspecific variation in antioxidant provision and provide evidence
for the role these antioxidants play during embryonic development.