"Les jeunes issus de copulations extra couple chez le Troglodyte ont plus de chance d'être des mâles que des femelles

Proceedings of the Royal Society B - Biological Sciences
22 June 2009 vol. 276 no. 1665 2285-2289
doi: 10.1098/rspb.2009.0283

Extra-pair young in house wren broods are more likely to be male than female

1. L. Scott Johnson1,*,
2. Charles F. Thompson2,
3. Scott K. Sakaluk2,
4. Markus Neuhäuser3,
5. Bonnie G.P. Johnson1,
6. Sheryl Swartz Soukup2,
7. Shannon Janota Forsythe2 and
8. Brian S. Masters1

-Author Affiliations

1.
1Department of Biological Sciences, Towson University
Towson, MD 21252, USA
2.
2Behavior, Ecology, Evolution, and Systematics Section, School of Biological Sciences, Illinois State University
Normal, IL 61790-4120, USA
3.
3Department of Mathematics and Technique, Koblenz University of Applied Sciences
53424 Remagen, Germany

Abstract

Sex-allocation theory predicts that females should preferentially produce offspring of the @#$%& with greater fitness potential. In socially monogamous animal species, extra-pair mating often increases the variance in fitness of sons relative to daughters. Thus, in situations where offspring sired by a female's extra-pair mate(s) will typically have greater fitness potential than offspring sired by the within-pair mate, @#$%&-allocation theory predicts that females will bias the @#$%& of offspring sired by extra-pair mates towards male. We examined the relationship between offspring @#$%& and paternity over six breeding seasons in an Illinois population of the house wren (Troglodytes aedon), a cavity-nesting songbird. Out of the 2345 nestlings that had both @#$%& and paternity assigned, 350 (15%) were sired by extra-pair males. The @#$%& ratio of extra-pair offspring, 0.534, was significantly greater than the @#$%& ratio of within-pair offspring, 0.492, representing an increase of 8.5 per cent in the proportion of sons produced. To our knowledge, this is the first confirmed report of female birds increasing their production of sons in association with extra-pair fertilization. Our results are consistent with the oft-mentioned hypothesis that females engage in extra-pair mating to increase offspring quality.

Marrant !!

Généralités et Environnement

les troglodytes illégitimes plus mâles ?