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Penguin chicks benefit from elevated yolk androgen levels under sibling competition
Maud Poisbleau1, Wendt Müller, David Carslake
1Department of Biology - Ethology, University of Antwerp, Wilrijk, Belgium. maud.poisbleau@ua.ac.be
Plos One
|August 4, 2012
Summary
Maternal yolk androgens in crested penguins (Eudyptes) enhance chick growth and survival, particularly in larger broods. This reinforces their hatching pattern and aids brood reduction.
Area of Science:
- Avian reproduction
- Behavioral ecology
- Endocrinology
Background:
- Crested penguins (Eudyptes) exhibit asynchronous hatching, with later-hatched chicks often having lower survival.
- Maternal yolk androgens are implicated in sibling competition and chick development in other species.
Purpose of the Study:
- To investigate the role of maternal yolk androgens in mediating sibling competition in crested penguins.
- To examine the effects of experimentally elevated yolk androgens on embryonic development, chick growth, and survival.
Main Methods:
- Freshly laid eggs from southern rockhopper penguins (Eudyptes chrysocome) were treated to increase yolk androgen levels.
- Treated and control eggs were placed in foster nests, matched for key parameters.
- Embryonic development, chick growth, and early survival were monitored.
Main Results:
- Androgen treatment did not significantly alter embryonic development or hatching measurements.
- Elevated yolk androgens improved chick growth and survival in the presence of siblings.
- The positive effect of androgens was more pronounced in larger broods.
Conclusions:
- Maternal yolk androgens reinforce the hatching hierarchy in crested penguins, promoting brood reduction.
- This finding contrasts with studies in other species where androgens may mitigate delayed hatching effects.
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