Egg-yolk androgen and carotenoid deposition as a function of maternal social environment in barn swallows Hirundo rustica

Rebecca J. Safran, Kevin McGraw, Kevin M. Pilz, Stephanie M. Correa

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Evidence is mounting that female animals use egg-yolk compounds (e.g. steroids, antioxidants) to adaptively engineer the quality of their offspring as a function of several maternal and environmental factors. Though adjustments to yolk allocation have been well-characterized as a function of parental phenotypes, we know very little about how an individual's social environment influences yolk composition. Here, we consider how two types of yolk compounds, androgens and carotenoids, relate to the maternal social environment during the egg-laying period, controlling statistically for known correlations between various aspects of parental quality and egg yolk compounds. Barn swallows Hirundo rustica erythrogaster breed in groups of highly variable size and spacing, allowing us to test whether or not the social environment is correlated with these maternal effects. We found no relationship between carotenoid levels in eggs as a function of colony size, colony density, or nearest-neighbor distance. However, eggs from females in larger groups had lower concentrations and total amounts of yolk androgens than those from females in smaller, less dense social settings. Our results counter previous predictions and literature, showing that females breeding in large groups deposit more androgen in eggs, mechanistically, because they compete more with conspecifics and have higher circulating androgen levels themselves and, functionally, because it could be advantageous for their offspring to show high androgen-mediated competitive abilities early in life. Instead, because group size in this species is governed largely by site fidelity and the availability of old nests for re-use, and because reproductive output does not differ as a function of group size, it may be that competition is greater for limited nests in small groups, thus elevating androgen levels. Further, yolk androgens were previously shown to be affected by male quality, and the greater concentrations and amounts of yolk androgens in smaller sites may reflect differential allocation to darker males found at these sites.

Original languageEnglish (US)
Pages (from-to)470-478
Number of pages9
JournalJournal of Avian Biology
Volume41
Issue number4
DOIs
StatePublished - Jul 2010

Fingerprint

Hirundo rustica
social environment
androgen
carotenoid
androgens
egg yolk
carotenoids
egg
group size
nest
nests
maternal effect
site fidelity
competitive ability
philopatry
steroid
engineers
antioxidant
steroids
phenotype

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Ecology, Evolution, Behavior and Systematics

Cite this

Egg-yolk androgen and carotenoid deposition as a function of maternal social environment in barn swallows Hirundo rustica. / Safran, Rebecca J.; McGraw, Kevin; Pilz, Kevin M.; Correa, Stephanie M.

In: Journal of Avian Biology, Vol. 41, No. 4, 07.2010, p. 470-478.

Research output: Contribution to journalArticle

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