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Sex allocation in a monomorphic seabird with a single-egg clutch: test of the environment, mate quality, and female condition hypotheses

TitleSex allocation in a monomorphic seabird with a single-egg clutch: test of the environment, mate quality, and female condition hypotheses
Publication TypeJournal Article
Year of Publication2008
AuthorsAddison, BA, Kitaysky, AS, J. Hipfner, M
JournalBehavioral Ecology and Sociobiology
Volume63
Pagination135–141
Abstract

Sex allocation theory posits that mothers shouldpreferentially invest in sons when environmental conditionsare favorable for breeding, their mates are of high quality,or they are in good body condition. We tested these threehypotheses in rhinoceros auklets (Cerorhinca monocerata),monomorphic seabirds that lay a single-egg clutch, in2 years that differed in environmental conditions forbreeding. Results supported the environment and matequality hypotheses, but these effects were interactive:offspring sex was independent of paternal traits in the pooryear for breeding, while females mated to larger and moreornamented males reared more sons in the better year.Conversely, offspring sex was unrelated to female condition,as indexed by hatching date. We propose that goodrearing conditions enable females to rear sons possessingthe desirable phenotypic attributes of their mates. Resultsalso supported two critical assumptions of sex allocationtheory: (1) dimorphism in offspring condition at independence:daughters fledged with higher baseline levels ofcorticosterone than sons and (2) differential costs of rearingsons versus daughters: mothers rearing sons when environmentalconditions were poor completed parental care inpoorer condition than mothers rearing daughters in thesame year and mothers rearing either sex when conditionswere better. These novel results may help to explain thedisparate results of previous studies of avian sex allocation.

DOI10.1007/s00265-008-0643-z
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