Reproductive traits on wild guanacos: What do steroid hormones tell us?

PANEBIANCO ANTONELLA; GREGORIO PABLO; RUPER PALME; OVEJERO AGUILAR RAMIRO; MAROZZI ANTONELA; LEGGIERI LEONARDO RAMÓN; TARABORELLI PAULA; CARMANCHAHI PABLO

Phoenix, Arizona

Congreso; 100th Annual Meeting of the American Society of Mammalogist; 2021

American Society of Mammalogists

The reproductive season represents a period of high energy demands and social interactions related to male competition and mating, and is associated with the activation ofthe adrenal and gonadal axes, which secrete glucocorticoids and testosterone, respectively. Territoriality can also influence the secretion of these hormones.We quantified the concentrations of fecal metabolites of cortisol (FCM) and testosterone (FTM) in adult males of a population of wild guanacos (Lama guanicoe), a resource-defence polygyny ungulate,during three periods of the reproductive season (group-formation, mating, post-mating). We collected fresh fecal samples non-invasively (n=227) fromterritorial (family, solitary) and non-territorial (bachelors, mixed groups) males during two seasons (2014, 2016). FCM levels increased during the mating and post-mating periods and were higher in 2014 (of low vegetation productivity) than in 2016. FCM levelsdid not differ among social groups. FTM levels were higher in the mating period and during 2016, and werehigher in solitary males and males from mixed groups compared to males in family groups.The increase in FCM and FTM levels during the mating period reinforces the idea that the patterns that model the life cycle of these South American camelids are strongly influenced by seasonal variation in energy demands and social interactions.These results also provide a good example of how intrinsic and extrinsic factors are combined in the modulation of physiological mediators during reproduction.