title: Sources of variance in a female fertility signal: exaggerated estrous swellings in a natural population of baboons.
abstract: Signals of fertility in female animals are of increasing interest to evolutionary biologists, a development that coincides with increasing interest in male mate choice and the potential for female traits to evolve under sexual selection. We characterized variation in size of an exaggerated female fertility signal in baboons and investigated the sources of that variance. The number of sexual cycles that a female had experienced after her most recent pregnancy ("cycles since resumption") was the strongest predictor of swelling size. Furthermore, the relationship between cycles since resumption and swelling size was most evident during rainy periods and was not evident during times of drought. Finally, we found significant differences in swelling size between individual females; these differences endured across cycles (i.e., were not explained by variation within individuals) and persisted in spite of ecological effects. This study is the first to provide conclusive evidence of significant variation in swelling size between female primates (controlling for cycles since resumption) and to demonstrate that ecological constraints influence variation in this signal of fertility.
authors.affiliation: Department of Biology, Duke University, Durham, NC, USA; National Evolutionary Synthesis Center, 2024 W Main St. Suite A200, Durham, NC 27705-4667, USA.
authors.forename: Courtney L
authors.initials: CL
authors.lastname: Fitzpatrick
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA; Institute of Primate Research, National Museums of Kenya, Nairobi, Kenya.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Altmann
authors.affiliation: Department of Biology, Duke University, Durham, NC, USA; Institute of Primate Research, National Museums of Kenya, Nairobi, Kenya.
authors.forename: Susan C
authors.initials: SC
authors.lastname: Alberts
keywords: Baboon; Estrous swelling; Fertility
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