Social network stability is impacted by removing a dominant male in replicate dominance hierarchies of a cichlid fish

Abstract

Individuals with high social rank within a dominance hierarchy often have priority access to resources relative to subordinate individuals, but these rank-dependent fitness effects may depend on the stability of the social hierarchy. Here we studied temporal changes in network structure and social relationships in experimentally perturbed social hierarchies of the cichlid Astatotilapia burtoni . By removing a dominant male in replicate groups, we triggered more status changes compared to control, subordinate male removal groups. At the individual level, we found that dominant male removal resulted in dominant males significantly increasing the rate of chases (‘chase strength’), but there was no significant increase in the rate of display (‘display strength’). Dominant male removal also led to several changes at the group level: network reciprocity and network stability decreased in response to dominant male removal, while network density was not affected by our treatment. However, in contrast to the individual level network measures, these group level effects were present in display networks but not in chase networks. Display networks mostly connect dominant males within the network, making display networks more sensitive to changes in the hierarchy. Together, our results provide novel insights into complex social dynamics in experimentally altered social dominance networks. • Cichlid fish form dominance hierarchies in which males fight for territories. • In groups of cichlid fish, we vacated a territory by removing a territorial male. • This created social instability and increased chase behaviour. • However, the instability was linked to changes in the display network only. • This is because display networks strongly connect territorial males in the network.