SREL Reprint #3302

Interactive effects of male and female age on extra-pair paternity in a socially monogamous seabird

Alejandra G. Ramos1, Schyler O. Nunziata2,3, Stacey L. Lance2, Cristina Rodríguez1, Brant C. Faircloth4,
Patricia Adair Gowaty4,5,6, and Hugh Drummond1

1Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México,
A.P. 70-275, 04510 Mexico, Mexico
2Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, USA
3Department of Biology, University of Kentucky, Lexington, KY, USA
4Department of Ecology and Evolutionary Biology, University of California Los Angeles,
Los Angeles, CA, USA
5Institute of the Environment and Sustainability, University of California Los Angeles,
Los Angeles, CA, USA
6Smithsonian Tropical Research Institute, Washington, DC, USA

Abstract: Females sometimes obtain older sires for their offspring through extra-pair interactions, but how female age influences paternity is largely unexplored and interactive effects across the age span of both sexes have not been analyzed. To test whether female choice of sire age varies with female age in
the blue-footed booby (Sula nebouxii), we examined associations between ages of both partners and the probability of extrapair paternity (EPP) in 350 broods of parents up to 22 years old in a single breeding season. Extra-pair paternity enables a female to select an alternative sire for her offspring and could function to avoid or achieve particular combinations of parental ages. A male age × female age interaction revealed that in young females (≤4 years), EPP decreased with increasing age of the social partner, whereas in old females (≥8 years), it increased. Moreover, sires of extra-pair (EP) chicks of young females paired to young males were on average 6.33 years older than the females' social partners. Since female boobies control copulatory access, this pattern could imply that young females choose old sires for their proven genetic quality and that old females avoid very old males because matings with them may risk infertility or genetic defects in offspring. Taking female age into account and observing across the whole age span may be necessary for understanding female age-based mate choice.

Keywords: Age, Female choice, Extra-pair paternity, Extra-pair sire, Infertility, Good genes

SREL Reprint #3302

Ramos, A. G., S. O. Nunziata, S. L. Lance, C. Rodríguez, B. C. Faircloth, P. A. Gowaty, and H. Drummond. 2014. Interactive effects of male and female age on extra-pair paternity in a socially monogamous seabird. Behavioral Ecology and Sociobiology 68: 1603-1609.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).