title: Experimental increase of testosterone increases boldness and decreases anxiety in male African striped mouse helpers.
abstract: Males of many species can adjust their behaviors to environmental conditions by changing reproductive tactics. Testosterone surges in adult breeding males typically inhibit the expression of paternal care while facilitating the expression of aggression during environmental changes. Similarly, in non-breeding philopatric males of cooperatively breeding species, up-regulation of testosterone may inhibit alloparental care while facilitating dispersal, i.e. males might become bolder and more explorative. We tested this hypothesis in philopatric male African striped mice, Rhabdomys pumilio. Striped mouse males can either remain in their natal groups providing alloparental care or they can disperse seeking mating opportunities. Compared to philopatric males, dispersed males typically show higher testosterone levels and lower corticosterone levels, and more aggression toward pups and same sex conspecifics. We experimentally increased the testosterone levels of the philopatric males kept in their family groups when pups were present. Testosterone-treated males did not differ significantly from control males in alloparental care and in aggression toward same-sex conspecifics. Compared to the control males, testosterone treated males were bolder, more active, and less anxious; they also showed lower corticosterone levels. The philopatric males were sensitive to our testosterone treatment for dispersal- and anxiety-like behavior but insensitive for social behaviors. Our results suggest a role of testosterone in dispersal.
authors.affiliation: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. Electronic address: julien.raynaud.42@gmail.com.
authors.forename: Julien
authors.initials: J
authors.lastname: Raynaud
authors.affiliation: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Université de Strasbourg, IPHC-DEPE, France; CNRS, UMR7178, 67087 Strasbourg, France; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa.
authors.forename: Carsten
authors.initials: C
authors.lastname: Schradin
mesh_terms: D000374:Aggression / Q000502:physiology*; D000818:Animals; D001007:Anxiety / Q000378:metabolism*; D003345:Corticosterone / Q000378:metabolism; D005106:Exploratory Behavior / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D009043:Motor Activity / Q000502:physiology; D051189:Murinae / Q000502:physiology*; D010332:Paternal Behavior / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000502:physiology; D012919:Social Behavior; D013739:Testosterone / Q000097:blood / Q000378:metabolism*
chemical_list: D013739:Testosterone; D003345:Corticosterone
keywords: Cooperative breeding; Dispersal; Exploration; Roamer; Shyness; Social flexibility; Solitary-living; Strategy