A1 Refereed original research article in a scientific journal
Socio-sexual behaviors and fecal hormone metabolites but not age predict female aggressive interactions in Macaca arctoides
Authors: Cerda-Molina Ana Lilia, Mayagoitia-Novales Lilian, de la O-Rodríguez Claudio, Borráz-León Javier I., Matamoros-Trejo Gilberto
Publisher: SPRINGER
Publication year: 2022
Journal: Behavioral Ecology and Sociobiology
Journal name in source: BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY
Journal acronym: BEHAV ECOL SOCIOBIOL
Article number: 16
Volume: 76
Issue: 1
Number of pages: 11
ISSN: 0340-5443
DOI: https://doi.org/10.1007/s00265-021-03118-w
Abstract
The role of androgens, age, and rank position in the regulation of intrasexual competition and aggression in primate males has been widely addressed but understudied in females. We studied whether fecal testosterone (fTm) and estradiol (fEm) metabolites, dominance rank, age, and male-to-female sexual behavior (a proxy for female sexual attractiveness) are predictors of aggression in eight focal females of stump-tailed macaques (Macaca arctoides). We analyzed the following aggressive interactions: focal female to female, focal female to male, and male to focal female aggression. We collected fecal samples of the eight adult focal females over a 1-year period along with observational sampling of aggressive and sexual behaviors. We measured hormone metabolites using a validated methanol extraction technique and I-125 radioimmunoassay kits. Our results showed that factors positively associated with increased female-to-female aggression were fEm levels, whereas female-to-male aggression was negatively associated with fTm levels and positively related with dominance rank. Social rank increased with age, but age did not affect any recorded aggressive behaviors. Male-to-female aggression was predicted by sexual behaviors but not by female hormonal levels. Further studies are needed to explore the role of age in female antagonistic interactions. Significance statement Proximate mechanisms (e.g., hormonal mechanisms) behind sexual selection processes (i.e., intrasexual competition and intersexual selection) are widely reported in the literature. However, studies on these mechanisms in primate females remain scarce. It is possible that steroid hormones and their metabolites in conjunction with individual attributes such as rank position and age may be involved in regulating socio-sexual behaviors in primate females. Using a validated methanol extraction method, we demonstrated that dynamics of fecal estradiol and fecal testosterone metabolites are associated with selective aggression against males or females as well as with sexual behaviors received from males. Moreover, we showed that the oldest females held the highest rank positions, probably facilitating social and sexual resources acquisition. The inclusion of steroid hormones and rank position may help to explain potential differences in both mate choice and mate competition between males and females of Macaca arctoides.
The role of androgens, age, and rank position in the regulation of intrasexual competition and aggression in primate males has been widely addressed but understudied in females. We studied whether fecal testosterone (fTm) and estradiol (fEm) metabolites, dominance rank, age, and male-to-female sexual behavior (a proxy for female sexual attractiveness) are predictors of aggression in eight focal females of stump-tailed macaques (Macaca arctoides). We analyzed the following aggressive interactions: focal female to female, focal female to male, and male to focal female aggression. We collected fecal samples of the eight adult focal females over a 1-year period along with observational sampling of aggressive and sexual behaviors. We measured hormone metabolites using a validated methanol extraction technique and I-125 radioimmunoassay kits. Our results showed that factors positively associated with increased female-to-female aggression were fEm levels, whereas female-to-male aggression was negatively associated with fTm levels and positively related with dominance rank. Social rank increased with age, but age did not affect any recorded aggressive behaviors. Male-to-female aggression was predicted by sexual behaviors but not by female hormonal levels. Further studies are needed to explore the role of age in female antagonistic interactions. Significance statement Proximate mechanisms (e.g., hormonal mechanisms) behind sexual selection processes (i.e., intrasexual competition and intersexual selection) are widely reported in the literature. However, studies on these mechanisms in primate females remain scarce. It is possible that steroid hormones and their metabolites in conjunction with individual attributes such as rank position and age may be involved in regulating socio-sexual behaviors in primate females. Using a validated methanol extraction method, we demonstrated that dynamics of fecal estradiol and fecal testosterone metabolites are associated with selective aggression against males or females as well as with sexual behaviors received from males. Moreover, we showed that the oldest females held the highest rank positions, probably facilitating social and sexual resources acquisition. The inclusion of steroid hormones and rank position may help to explain potential differences in both mate choice and mate competition between males and females of Macaca arctoides.
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