Browsing by Author "Fitzpatrick, Courtney"
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Item Open Access Organizational and activational androgens, lemur social play, and the ontogeny of female dominance.(Hormones and behavior, 2019-07-02) Grebe, Nicholas M; Fitzpatrick, Courtney; Sharrock, Katherine; Starling, Anne; Drea, Christine MThe role of androgens in shaping "masculine" traits in males is a core focus in behavioral endocrinology, but relatively little is known about an androgenic role in female aggression and social dominance. In mammalian models of female dominance, including the ring-tailed lemur (Lemur catta), links to androgens in adulthood are variable. We studied the development of ring-tailed lemurs to address the behavioral basis and ontogenetic mechanisms of female dominance. We measured behavior and serum androgen concentrations in 24 lemurs (8 males, 16 females) from infancy to early adulthood, and assessed their 'prenatal' androgen milieu using serum samples obtained from their mothers during gestation. Because logistical constraints limited the frequency of infant blood sampling, we accounted for asynchrony between behavioral and postnatal hormone measurements via imputation procedures. Imputation was unnecessary for prenatal hormone measurements. The typical sex difference in androgen concentrations in young lemurs was consistent with adult conspecifics and most other mammals; however, we found no significant sex differences in rough-and-tumble play. Female (but not male) aggression increased beginning at approximately 15 months, coincident with female puberty. In our analyses relating sexually differentiated behavior to androgens, we found no relationship with activational hormones, but several significant relationships with organizational hormones. Notably, associations of prenatal androstenedione and testosterone with behavior were differentiated, both by offspring sex and by type of behavior within offspring sexes. We discuss the importance of considering (1) missing data in behavioral endocrinology research, and (2) organizational androgens other than testosterone in studies of female dominance.Item Open Access Revisiting Sexual Selection: An Exaggerated Signal of Fertility in the Amboseli Baboons(2012) Fitzpatrick, CourtneySexual selection has long been accepted as a widespread force of evolution shaping male traits across taxa. In recent years, biologists have begun to investigate the extent to which sexual selection may also shape traits among females. However, current models of sexual selection have largely been developed using assumptions that--while generally met in males--often do not apply to females. Thus, attempts to apply these contemporary models to the study of sexual selection in females reveal weaknesses in the theoretical framework for sexual selection research. One consequence of this for empirical research is that researchers often infer the action of sexual selection upon evidence of male mate choice. Although male mate choice is increasingly common, it is much less likely to exert selection pressure than its female counterpart. I begin by proposing a conceptual framework that explicitly accounts for ...Next, I investigate a female trait that has recently become an iconic example of sexual selection in females; that is the exaggerated estrous swellings of cercopithecine primates. By combining morphological data collected with a non-invasive photographic method and observational behavioral data with longitudinal ecological and demographic data from the ongoing Amboseli Baboon Research Project, I examine the sources of variance in this exaggerated signal of fertility. Finally, I test the hypothesis that male baboons prefer females with larger sexual swellings because those females have higher fitness. I find no evidence to support this hypothesis. Instead, my results suggest that mate choice among male baboons has evolved to detect, not the intrinsic quality of the female as has typically been proposed, but the quality of a reproductive opportunity.