Maternal testosterone in the avian egg enhances postnatal growth.

@article{Schwabl1996MaternalTI,
  title={Maternal testosterone in the avian egg enhances postnatal growth.},
  author={Hubert Schwabl},
  journal={Comparative biochemistry and physiology. Part A, Physiology},
  year={1996},
  volume={114 3},
  pages={
          271-6
        }
}
  • H. Schwabl
  • Published 1 July 1996
  • Biology
  • Comparative biochemistry and physiology. Part A, Physiology
Negative effects of yolk testosterone and ticks on growth in canaries.
TLDR
The effects of elevated yolk testosterone on growth may be dose-dependent or vary with the egg quality, suggesting prenatal context-dependency.
Environment modifies the testosterone levels of a female bird and its eggs.
  • H. Schwabl
  • Biology
    The Journal of experimental zoology
  • 1996
TLDR
It is concluded that here the authors have a mechanism which communicates environmental conditions from the mother to the offspring, and that this mechanism serves to optimize reproduction and/or modify offspring traits.
Maternal testosterone in tree swallow eggs varies with female aggression
TLDR
In tree swallows, Tachycineta bicolor, it is found that yolk testosterone was correlated with the aggressive interactions of the female before and during egg laying and did not vary with laying order in tree swallow.
Sex-specific effects of yolk-androgens on growth of nestling American kestrels
TLDR
It is discovered that male nestlings were more susceptible than female nestlings to growth inhibition by yolk-androgen elevation but did not find a bias in sex ratio with respect to laying order, consistent with the hypothesis that sex differences in yolks enable mothers to economically tune reproductive effort to an individual offspring’s reproductive value.
Effects of elevated yolk testosterone levels on survival, growth and immunity of male and female yellow-legged gull chicks
TLDR
The results suggest that female yellow-legged gulls may be constrained in transferring androgens to their eggs by negative consequences on the viability of female offspring and growth of chicks of the two sexes.
Yolk androgens reduce offspring survival
TLDR
Additional studies are necessary in order to determine whether the deposition of yolk androgens is an adaptive form of parental favouritism or an adverse by–product of endocrine processes during egg formation, despite its adaptive significance.
Functional significance of variation in egg-yolk androgens in the American coot
TLDR
Within clutches, early-laid eggs had higher androgen levels than late-laying eggs, and this pattern may exacerbate negative effects of hatching asynchrony on chicks from late-hatching eggs if androgens provide chicks with a behavioral or growth advantage over chicks from eggs with lower androgens levels.
Yolk testosterone, postnatal growth and song in male canaries
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References

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  • H. Schwabl
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
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TLDR
These findings indicate that female songbirds can bestow upon their eggs a dose of hormone that modifies the behavior of offspring, suggesting that variable doses of these hormones might explain some of the individual variation in offspring behavior.
Food Supply and the Annual Timing of Avian Reproduction
TLDR
It is shown that with constraints on parental investment, optimal clutch sizes should decline with season when egg reproductive value declines, independent on the nature of the constraining and proximate control mechanisms.
INTRASPECIFIC VARIATION IN EGG SIZE AND EGG COMPOSITION IN BIRDS: EFFECTS ON OFFSPRING FITNESS
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It is suggested that the most important effect of variation in egg size might be in determining the probability of offspring survival in the first few days after hatching, and the hypothesis that large eggs give rise to heavier chicks at hatching is supported.
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By manipulating both food availability and brood hierarchies, and following offspring survival after fledging, it is shown that in blackbirds (Turdus merula) asynchronous broods are more productive whenFood is scarce, but not when food is abundant.
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TLDR
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    Proceedings of the National Academy of Sciences of the United States of America
  • 1993
TLDR
The results show that the behavioral dominance of canary fledglings is positively and significantly related to the yolk testosterone concentrations of the eggs from which they hatched, and this opens up a new chapter in the understanding of just what those maternal resources can include.
Seasonality of clutch size determination in the Kestrel Falco tinnunculus: An experimental approach
TLDR
The higher level of incubation tendency in late breeders at the onset of laying may be instrumental in more rapid follicle resorption and hence in clutch size reduction in Kestrel clutches.
Hatching asynchrony in the mountain white-crowned sparrow (Zonotrichia leucophrys oriantha): a selected or incidental trait?
TLDR
It is proposed that hatching asynchrony is an epiphenomenon of the hormonal mechanism governing egg-laying and incubation and provides a testable alternative to existing "adaptive" hypotheses.
Adaptive seasonal variation in the sex ratio of kestrel broods
TLDR
The sex ratio (% males) in broods of European kestrels, Falco tinnunculus L., declined with progressive date of birth, and enhanced reproductive prospects of the broods since the probability of breeding as yearling declined with birth date for male offspring, but not for females.
Incubation during the egg-laying period in relation to clutch-size and other aspects of reproduction in the Great Tit Parus major
TLDR
Because the mortality of the latest hatched young increases with age difference within broods, selection tends to keep the incubation time in the egg-laying period below a certain 'critical' level (about 1000 minutes).
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