Yolk Testosterone Stimulates Growth and Immunity in House Finch Chicks

Female birds deposit variable amounts of androgens, such as testosterone, into the yolks of their eggs. Evidence suggests that yolk androgens play an important role in the determination of offspring phenotype. While androgens are generally regarded as anabolic and immunosuppressive, studies of the b...

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Bibliographic Details
Published in:Physiological and biochemical zoology 2006-05, Vol.79 (3), p.550-555
Main Authors: Navara, Kristen J., Hill, Geoffrey E., Mendonça, Mary T.
Format: Article
Language:English
Subjects:
Androgens
Animals
Chicks
Egg Yolk - immunology
Egg Yolk - physiology
Eggs
Female
Female animals
Finches
Finches - growth & development
Finches - immunology
Hatching
Immunity
Immunity, Cellular - immunology
Immunity, Cellular - physiology
Male
Peanut oil
Phytohemagglutinins - immunology
Tarsus
Testosterone
Testosterone - immunology
Testosterone - physiology
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Summary:Female birds deposit variable amounts of androgens, such as testosterone, into the yolks of their eggs. Evidence suggests that yolk androgens play an important role in the determination of offspring phenotype. While androgens are generally regarded as anabolic and immunosuppressive, studies of the behavioral and physiological effects of yolk androgens on offspring of several avian species have been conflicting, leaving the adaptive significance associated with deposition patterns of yolk androgens unclear. We injected either a physiological dose of testosterone or a control vehicle into house finch (Carpodacus mexicanus) eggs and examined the effects of these injections on offspring growth and immunity. Two days after hatching, nestlings from eggs treated with testosterone were significantly larger than nestlings from eggs treated with a control injection, suggesting a stimulatory effect of yolk androgens in early development. By 8 d after hatching, however, this effect disappeared, and chicks from the two treatment groups were similar in size. Nestlings in the testosterone treatment group showed a significantly larger swelling response to phytohemagglutinin than control nestlings 15 d after hatching, which is close to fledging. Overall, our observations show that when food resources are abundant, testosterone stimulates both early growth and immunity in developing house finches.
ISSN:1522-2152
1537-5293
DOI:10.1086/501054