Behavioral changes during social ascent and descent in replicate social networks of an African cichlid fish.

Within social dominance hierarchies, rank has a major impact on health and fitness. Dominance hierarchies are rarely stable as individuals may change rank due to changes in the social environment. Here we describe general group-level social network properties and changes in social ties and behavior during rank transitions in 16 communities of the cichlid Astatotilapia burtoni. Social networks based on chases were dense with dominant males frequently chasing subordinate males and females. This intense territoriality of dominant males was also reflected by a high degree of 'power' inequality. Compared to chase-based networks, display-based networks were characterized by a high degree of reciprocity due to display behaviors mostly occurring bidirectionally among a few highly ranked males. Territory ownership is tightly linked to social dominance and territory loss (i.e., social descent) was, as expected, associated with a sharp reduction in aggression level and an increase in chases received. However, although territory acquisition (i.e., social ascent) was an abrupt process, ascending males displayed elevated aggression prior to ascent, in sharp contrast to previous studies carried out in less complex settings. Together, our results provide novel insights into dynamic changes in behavior in cichlid dominance hierarchies. [ABSTRACT FROM AUTHOR]