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Food supplementation reveals constraints and adaptability of egg quality in the magpie Pica pica

Posted on 18. February, 2016.

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In addition to genetic effects, parents can affect offspring fitness traits through changes in propagule size, number or quality. These parental effects, especially maternal effects, may provide a mechanism for ‘phenotypic engineering’ which allows offspring to be adapted to variable environmental conditions. 

Differences in the deposition of limited maternal resources to eggs can reflect the optimal allocation to manipulate offspring phenotype, or constraints caused by maternal condition. We examined multiple maternal substances transferred to eggs in the magpie Pica pica to test the hypothesis that certain substances represent constraint and some optimal allocation. We did this by supplementary feeding magpies prior to egg-laying and then comparing the effect of food on maternal substances in conjunction with laying order relative to a control group. Certain substances such as carotenoids, immunoglobulins and avidin responded positively to food supplementation, whereas others, such as testosterone and total protein content of eggs, did not. Immunoglobulin allocation increased with laying order in fed but not in unfed groups. Our results suggest that patterns of optimal allocation and constraint in maternally-provisioned substances co-occur within clutches. Furthermore, constraint and optimal allocation may co-occur within the same substance i.e. immunoglobulins, highlighting the complexities of maternal resource allocation.

Keywords: maternal effects, hatching asynchrony, carotenoids, testosterone, immunoglobulins

Read the full article in Avian Biology Research, Volume 8, Number 4, December 2015, pp. 244-253.

Authors: Heli Siitaria, Rauno Alataloa†, Marjo Pihlajaa, Jenny Hämäläinena, Jonathan D.Blountb, Ton G. Groothuisc, Vesa P. Hytönend,g, Peter Suraie and Carl D. Soulsburya,f*

aDepartment of Biological and Environmental Science, Evolutionary Research, University of Jyväskylä, Finland
bCentre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, UK
cBehavioural Biology, Groningen Institute of Evolutionary Life Sciences, University of Groningen, The Netherlands
dDepartment of Biological and Environmental Science, Molecular Recognition, University of Jyväskylä, Finland
eDepartment of Animal Nutrition, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, Hungary
fSchool of Life Sciences, Joseph Banks Laboratories, University of Lincoln, UK
gBioMediTech, University of Tampere and Fimlab Laboratories, Finland
Deceased 9 November 2012

DOI:10.3184/175815515X14460614674603

Image: Eurasian Magpie (P.pica). By Teemu Lehtinen from Salo / Helsinki, Finland [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons