Fighting investment of Neolamprologus pulcher after receiving single, reinforcing, and contradictory contest experiences

When animals live in long-term groups, the potential for conflict is high.
Conflict is costly, so an individual’s decision to engage depends on the
information it has about the costs and benefits of fighting. One source of
information could be past contest experience, where previous
winners/losers typically become more likely to win/lose in the future.
However, repeated interactions can familiarize individuals with conflict
and provide opportunities to learn to become better fighters, regardless
of outcome. We explored how individuals integrate information from
previous contests to inform future encounters in a group-living fish,
Neolamprologus pulcher. We gave contestants single, reinforcing, and
contradictory experiences and measured behavior and post-fight water-borne
levels of androgenic steroids (testosterone, 11-ketotestosterone).
Contradictory outcomes were associated with reduced investment in
fighting. More fighting experience did not lead to greater investment in
fighting, as consecutive losses resulted in reduced aggression. Also,
there was no effect of fighting treatment on water-borne androgen
concentrations. Interestingly, there were sex differences in which
behaviors were influenced by experience, and in whether body mass was
associated with androgen concentrations, which could indicate that males
and females vary in how perceived fighting ability changes with contest
experience. Our data reveal the complex ways in which repeated experiences
can alter an individual’s propensity to invest in conflict. Repeated
interactions associated with predictable changes in behavior can
contribute to rank stability in groups and our results indicate that
whether and how they do depend on the quality and quantity of interactions
plus individual factors such as sex.