Skip to content

Experimental evidence that intruder and group member attributes affect outgroup defence and associated within-group interactions in a social fish

Research output: Contribution to journalArticle

Original languageEnglish
Article number20191261
Number of pages9
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1912
DateAccepted/In press - 17 Sep 2019
DatePublished (current) - 9 Oct 2019


In many social species, individuals communally defend resources from conspecific outsiders. Participation in defence and in associated within-group interactions, both during and after contests with outgroup rivals, is expected to vary between group members because the threat presented by different outsiders is not the same to each individual. However, experimental tests examining both the contributions to, and the consequences of, outgroup conflict for all group members are lacking. Using groups of the cichlid Neolamprologus pulcher, we simulated territorial intrusions by different-sized female rivals and altered the potential contribution of subordinate females to defence. Dominant females and subordinate females defended significantly more against size- and rank-matched intruders, while males displayed lower and less variable levels of defence. Large and small, but not intermediate-sized, intruders induced increased levels of within-group aggression during intrusions, which was targeted at the subordinate females. Preventing subordinate females from helping in territorial defence led to significant decreases in post-contest within-group and female-specific submissive and affiliative displays. Together, these results show that the defensive contributions of group members vary greatly depending both on their own traits and on intruder identity, and this variation has significant consequences for within-group social dynamics both during and in the aftermath of outgroup contests.

    Research areas

  • Defensive contributions, Neolamprologus pulcher, Outgroup conflict, Social interactions, Territorial intrusions

Download statistics

No data available



  • Full-text PDF (final published version)

    Rights statement: This is the final published version of the article (version of record). It first appeared online via The Royal Society at . Please refer to any applicable terms of use of the publisher.

    Final published version, 627 KB, PDF document

    Licence: CC BY


View research connections

Related faculties, schools or groups