Functions of post-conflict bystander affiliations toward aggressors and victims in bottlenose dolphins

Abstract

Post-conflict affiliations initiated by bystanders (bystander affiliation) toward aggressors or victims have been suggested to represent the function of conflict management in some social living species. However, the function of bystander affiliations toward aggressors and victims has not been examined in marine mammals. In the present study, we investigated the function of bystander affiliations to aggressors and victims in bottlenose dolphins: self-protection, the substitute of reconciliation, social facilitation and tension relief of opponents. These bystander affiliations did not reduce post-conflict attacks by former opponents against group members. Bystander affiliation to aggressors tended to be performed by a bystander who had an affiliative relationship with the aggressor but not with the victim. Bystander affiliation to victims also tended to be initiated by a bystander who had an affiliative relationship with the victim but not the aggressor and was close to former opponents at the end of aggressions. Affiliation among group members who stayed near former opponents during aggressions did not increase after aggressions compared to that under control conditions. Renewed aggressions between former opponents decreased after bystander affiliations in our previous study. Bystanders who showed social closeness to former opponents may initiate bystander affiliation toward their affiliative former opponents because they may feel emotion, such as anxiety and excitement, of former opponents. Bystander affiliation toward aggressors and victims may function as tension relief between former opponents. Bystanders of bottlenose dolphins, who may have a relaxed dominant style, might initiate post-conflict affiliation to affiliative individuals unaffected by the dominance relationships among them, unlike despotic species. Animals which live in social groups often experience aggression. Aggression involves various costs, such as damage to social relationships, increasing the stress, increasing risk of receiving attack, the use of time and energy and risk of injury. Strategies that reduce aggression costs, called conflict management, include post-conflict affiliation between former opponents and post-conflict affiliation initiated by bystanders toward former opponents 1. In several primates and non-primates, post-conflict affiliation is sometimes offered to former opponents by bystanders who do not participate in aggression 1. A key area of research is focused the function of post-conflict affiliation initiated by bystanders 2,3 , with several possible function being suggested for bystander affiliations in several animals. The first possible function is self-protection by bystanders. Bystanders are likely to be attacked by aggressors and victims after the original aggressions 4-6. The probability of receiving post-conflict attacks from former opponents decreased when bystander affiliation occurred 7-11. In contrast, self-protection from attack by a victim toward group members was not supported in Barbary macaques (Macaca ...

Witness for resolution: post-conflict quadratic affiliation in semi-free ranging pigs

“…To our knowledge, so far quadratic affiliation has been only reported in primates and specifically in three out of four African monkey species investigated for the presence of the phenomenon, namely Japanese macaques, ( Macaca fuscata , Daniel and Alves 2015 ), hamadryas baboons ( Papio hamadryas : Judge and Mullen 2005 ), and Tonkean macaques ( Macaca tonkeana , De Marco et al 2010 ) but not geladas ( Theropithecus gelada , Leone et al 2010 ). Interestingly, no quadratic affiliation has been detected in bottlenose dolphins Tursiops truncatus , which show both reconciliation and triadic contacts ( Yamamoto et al 2015 , 2020 ). The absence of quadratic affiliation appears to be associated with tolerant species possessing relaxed dominance style, which would make conflicts not so stressful to induce affiliation between bystanders ( Leone et al 2010 ; Daniel and Alves 2015 ; Yamamoto et al 2020 ).…”

“…Interestingly, no quadratic affiliation has been detected in bottlenose dolphins Tursiops truncatus , which show both reconciliation and triadic contacts ( Yamamoto et al 2015 , 2020 ). The absence of quadratic affiliation appears to be associated with tolerant species possessing relaxed dominance style, which would make conflicts not so stressful to induce affiliation between bystanders ( Leone et al 2010 ; Daniel and Alves 2015 ; Yamamoto et al 2020 ).…”