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Author Flack, J.C.; de Waal, F.B.M.; Krakauer, D.C. doi  openurl
  Title Social structure, robustness, and policing cost in a cognitively sophisticated species Type Journal Article
  Year 2005 Publication The American Naturalist Abbreviated Journal Am Nat  
  Volume 165 Issue 5 Pages E126-139  
  Keywords Animals; *Behavior, Animal; Cognition; Conflict (Psychology); Female; Macaca nemestrina/*physiology; Male; Models, Biological; *Social Behavior  
  Abstract Conflict management is one of the primary requirements for social complexity. Of the many forms of conflict management, one of the rarest and most interesting is third-party policing, or intervening impartially to control conflict. Third-party policing should be hard to evolve because policers personally pay a cost for intervening, while the benefits are diffused over the whole group. In this study we investigate the incidence and costs of policing in a primate society. We report quantitative evidence of non-kin policing in the nonhuman primate, the pigtailed macaque. We find that policing is effective at reducing the intensity of or terminating conflict when performed by the most powerful individuals. We define a measure, social power consensus, that predicts effective low-cost interventions by powerful individuals and ineffective, relatively costly interventions by low-power individuals. Finally, we develop a simple probabilistic model to explore whether the degree to which policing can effectively reduce the societal cost of conflict is dependent on variance in the distribution of power. Our data and simple model suggest that third-party policing effectiveness and cost are dependent on power structure and might emerge only in societies with high variance in power.  
  Address Santa Fe Institute, Santa Fe, New Mexico 87501, USA. jflack@santafe.edu  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1537-5323 ISBN Medium  
  Area Expedition Conference  
  Notes (up) PMID:15795848 Approved no  
  Call Number refbase @ user @ Serial 168  
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Author Cameron, E.Z.; du Toit, J.T. doi  openurl
  Title Winning by a neck: tall giraffes avoid competing with shorter browsers Type Journal Article
  Year 2007 Publication The American naturalist Abbreviated Journal Am Nat  
  Volume 169 Issue 1 Pages 130-135  
  Keywords Acacia/growth & development; Animals; Feeding Behavior/*physiology; Neck/*anatomy & histology; Plant Leaves/growth & development; Ruminants/*anatomy & histology/*physiology; South Africa  
  Abstract With their vertically elongated body form, giraffes generally feed above the level of other browsers within the savanna browsing guild, despite having access to foliage at lower levels. They ingest more leaf mass per bite when foraging high in the tree, perhaps because smaller, more selective browsers deplete shoots at lower levels or because trees differentially allocate resources to promote shoot growth in the upper canopy. We erected exclosures around individual Acacia nigrescens trees in the greater Kruger ecosystem, South Africa. After a complete growing season, we found no differences in leaf biomass per shoot across height zones in excluded trees but significant differences in control trees. We conclude that giraffes preferentially browse at high levels in the canopy to avoid competition with smaller browsers. Our findings are analogous with those from studies of grazing guilds and demonstrate that resource partitioning can be driven by competition when smaller foragers displace larger foragers from shared resources. This provides the first experimental support for the classic evolutionary hypothesis that vertical elongation of the giraffe body is an outcome of competition within the browsing ungulate guild.  
  Address Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. ezcameron@zoology.up.ac.za  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1537-5323 ISBN Medium  
  Area Expedition Conference  
  Notes (up) PMID:17206591 Approved no  
  Call Number refbase @ user @ Serial 410  
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