title: Beyond aggression: Androgen-receptor blockade modulates social interaction in wild meerkats.
abstract: In male vertebrates, androgens are inextricably linked to reproduction, social dominance, and aggression, often at the cost of paternal investment or prosociality. Testosterone is invoked to explain rank-related reproductive differences, but its role within a status class, particularly among subordinates, is underappreciated. Recent evidence, especially for monogamous and cooperatively breeding species, suggests broader androgenic mediation of adult social interaction. We explored the actions of androgens in subordinate, male members of a cooperatively breeding species, the meerkat (Suricata suricatta). Although male meerkats show no rank-related testosterone differences, subordinate helpers rarely reproduce. We blocked androgen receptors, in the field, by treating subordinate males with the antiandrogen, flutamide. We monitored androgen concentrations (via baseline serum and time-sequential fecal sampling) and recorded behavior within their groups (via focal observation). Relative to controls, flutamide-treated animals initiated less and received more high-intensity aggression (biting, threatening, feeding competition), engaged in more prosocial behavior (social sniffing, grooming, huddling), and less frequently initiated play or assumed a 'dominant' role during play, revealing significant androgenic effects across a broad range of social behavior. By contrast, guarding or vigilance and measures of olfactory and vocal communication in subordinate males appeared unaffected by flutamide treatment. Thus, androgens in male meerkat helpers are aligned with the traditional trade-off between promoting reproductive and aggressive behavior at a cost to affiliation. Our findings, based on rare endocrine manipulation in wild mammals, show a more pervasive role for androgens in adult social behavior than is often recognized, with possible relevance for understanding tradeoffs in cooperative systems.
authors.affiliation: Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa; Department of Evolutionary Anthropology, Duke University, Durham, USA; School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK.
authors.forename: Javier
authors.initials: J
authors.lastname: delBarco-Trillo
authors.affiliation: Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa; Department of Evolutionary Anthropology, Duke University, Durham, USA; University Program in Ecology, Duke University, Durham, USA.
authors.forename: Lydia K
authors.initials: LK
authors.lastname: Greene
authors.affiliation: Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa; Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
authors.forename: Ines Braga
authors.initials: IB
authors.lastname: Goncalves
authors.affiliation: Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa; Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
authors.forename: Miriam
authors.initials: M
authors.lastname: Fenkes
authors.affiliation: Department of Evolutionary Anthropology, Duke University, Durham, USA.
authors.forename: Jillian H
authors.initials: JH
authors.lastname: Wisse
authors.affiliation: Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa; Royal Veterinary College, University of London, London, UK.
authors.forename: Julian A
authors.initials: JA
authors.lastname: Drewe
authors.affiliation: Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa; Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland; Mammal Research Institute, University of Pretoria, Pretoria, South Africa.
authors.forename: Marta B
authors.initials: MB
authors.lastname: Manser
authors.affiliation: Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa; Mammal Research Institute, University of Pretoria, Pretoria, South Africa; Department of Zoology, University of Cambridge, Cambridge, UK.
authors.forename: Tim
authors.initials: T
authors.lastname: Clutton-Brock
authors.affiliation: Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa; Department of Evolutionary Anthropology, Duke University, Durham, USA; University Program in Ecology, Duke University, Durham, USA; Department of Biology, Duke University, Durham, USA. Electronic address: cdrea@duke.edu.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Drea
mesh_terms: D000374:Aggression / Q000187:drug effects / Q000502:physiology*; D059002:Androgen Receptor Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D004291:Dominance-Subordination; D005260:Female; D005485:Flutamide / Q000008:administration & dosage / Q000494:pharmacology*; D008988:Herpestidae / Q000502:physiology*; D008297:Male; D012919:Social Behavior; D013739:Testosterone / Q000502:physiology*
chemical_list: D059002:Androgen Receptor Antagonists; D013739:Testosterone; D005485:Flutamide
keywords: Aggression; Antiandrogen; Behavioral neuroendocrinology; Communication; Cooperative breeder; Field experiment; Flutamide; Prosocial behavior; Subordinate male; Testosterone