Abstract
Offspring survival can be influenced by resources allocated to eggs, which in turn may be affected by the environmental factors the mother experiences during egg formation. In this study, we investigated whether experimentally elevated social interactions and number of neighbouring pairs influence yolk composition of collared flycatchers (Ficedula albicollis). Social challenge was simulated by presentation of a conspecific female. Experimental females spent more time near the cage and produced eggs with higher androgen concentration, but local breeding density did not affect yolk androgen level. Moreover, we found that females exposed to more intra-specific interactions and those that bred at higher density produced eggs with smaller yolk. These females may be more constrained in foraging time due to more frequent social encounters, and there might be increased competition for food at areas of higher density. In contrast, the present study did not reveal any evidence for the effect of social environment on yolk antioxidant and immunoglobulin levels. However, we found that yolk lutein and immunoglobulin concentrations were related to the female’s H/L ratio. Also, yolk lutein and α-tocopherol levels showed a seasonal increase and were positively related to the female’s plasma carotenoid level. Mothers may incur significant costs by transferring these compounds into the eggs, thus only females in good physiological condition and those that lay eggs later, when food is probably more abundant, could allocate higher amounts to the eggs without compromising their defence mechanisms. Our results suggest that environmental circumstances during egg formation can influence conditions for embryonic development.
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Acknowledgements
We are grateful to R. Főző, L.Z. Garamszegi, G. Hegyi, M. Laczi, G. Nagy, B. Rosivall, B. Szigeti and E. Szöllősi for assistance during fieldwork. We are grateful to P. Péczely and Zs. Szőke for laboratory analysis of yolk testosterone. We are indebted to Zs. Greff, S.D. Larcombe, A. Adams and W. Mullen for their invaluable advice and help in the laboratory analyses. We thank G. Hegyi, K.J. Navara, S. Healy, Á. Lendvai and two anonymous reviewers for their helpful comments that greatly improved the manuscript. This study was supported by the Hungarian Scientific Research Fund (OTKA, grants no. T49650 and T49678), the Eötvös Loránd University, the Erdők a Közjóért Alapítvány, and the Pilis Park Forestry. R.H. was supported during her stay at DEEB of the University of Glasgow by an international exchange grant of the Royal Society of Edinburgh. The Hungarian Ministry of Environment and Water provided permissions for the collection of collared flycatcher eggs for this study (permission no. 15951/2005).
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Hargitai, R., Arnold, K.E., Herényi, M. et al. Egg composition in relation to social environment and maternal physiological condition in the collared flycatcher. Behav Ecol Sociobiol 63, 869–882 (2009). https://doi.org/10.1007/s00265-009-0727-4
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DOI: https://doi.org/10.1007/s00265-009-0727-4