title: Testosterone is associated with harem maintenance ability in free-ranging grey-headed flying-foxes, Pteropus poliocephalus.
abstract: Males of many vertebrate species aggressively defend their reproductive interests by monopolizing females, and the 'challenge hypothesis' predicts that testosterone levels in reproductive contexts rise to facilitate males' competitive behaviours necessary for meeting social challenges. The hypothesis is successful in explaining patterns of testosterone secretion in many avian species, but remains comparatively unexplored in mammals. 'Circulating plasma testosterone levels (T)' were studied in relation to harem maintenance in grey-headed flying-foxes, Pteropus poliocephalus. In this species, harems provide mating opportunities and so a male's ability to maintain a harem is likely to correlate with his fitness. We hypothesized that if T reflect a male's ability to withstand challenges from competitors, then T should be linked to successful harem maintenance. To test this, we temporarily removed males from their territories prior to and during the short mating period, recording their harem sizes both before removal and after reintroduction. Most males successfully reclaimed their territory and a harem, but during the mating period, males with higher T had harems closer to their original size, and males with lower T suffered reduction in harem size. Our findings highlight the role of T in harem maintenance in a major mammalian taxon with complex forms of social organization.
authors.affiliation: Institute of Experimental Ecology, University of Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany. stefan.klose@uni-ulm.de
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Klose
authors.forename: Justin A
authors.initials: JA
authors.lastname: Welbergen
authors.forename: Elisabeth K V
authors.initials: EK
authors.lastname: Kalko
mesh_terms: D000818:Animals; D002685:Chiroptera / Q000097:blood*; D003163:Competitive Behavior; D005260:Female; D008297:Male; D012726:Sexual Behavior, Animal; D013731:Territoriality; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone
references.citation: Neurosci Biobehav Rev. 2006;30(3):319-45
references.pmid: 16483890
references.citation: Biol Lett. 2008 Dec 23;4(6):741-4
references.pmid: 18700197
references.citation: Proc Biol Sci. 2009 Mar 7;276(1658):971-80
references.pmid: 19129132
references.citation: Proc Biol Sci. 2008 Feb 22;275(1633):419-25
references.pmid: 18048286
references.citation: Steroids. 1975 Sep;26(3):311-21
references.pmid: 1198621
references.citation: Horm Behav. 2006 Apr;49(4):484-500
references.pmid: 16380123
references.citation: Anim Behav. 1965 Oct;13(4):544-57
references.pmid: 5882814
references.citation: J Reprod Fertil. 1991 Jul;92(2):347-52
references.pmid: 1886093
references.citation: Horm Behav. 2007 Apr;51(4):461-2
references.pmid: 17400224
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2006 Apr;192(4):341-50
references.pmid: 16273409
references.citation: J Vet Med Sci. 1998 May;60(5):643-5
references.pmid: 9637303