Responsiveness to contest experiences is associated with competitive ability but not aggressiveness or boldness

Abstract: Many animals raise and lower aggressiveness after recent wins and losses, respectively. Individuals that differ in internal/external conditions could also differ in their responsiveness to winning and/or losing experiences. Personality traits have been suggested to have close links with an individual’s responsiveness to environmental stimuli. Whether the responsiveness to winning-losing experiences is related to personality traits, however, remains unclear. Using a mangrove killifish, this study tested the hypothesis that personality traits (aggressiveness and boldness) and responsiveness to winning/losing experiences are linked because of their common associations with competitive ability. We also measured oxygen consumption rates to evaluate the importance of energy supply to the responsiveness. The results showed that aggressiveness, but not boldness or oxygen consumption rate, was associated with competitive ability and affected by winning/losing experiences. The fish’s responsiveness to winning-losing experiences was dependent only on competitive ability, but not aggressiveness or boldness; individuals with better (instead of worse) competitive abilities showed greater decreases in aggressiveness in response to losing experiences. The strong signals from multiple losing experiences together with worse competitors also exhibiting low aggressiveness (floor effects) may have given rise to these unpredicted results. Furthermore, (1) aggressiveness, boldness and oxygen consumption rate were positively correlated both before and after experience treatments and (2) individuals that were bolder or had higher oxygen consumption rates had higher increases in aggressiveness after experience treatments, consistent with the notion that individuals that are able to pay high metabolic costs can afford to behave boldly and aggressively and to raise aggressiveness further. Significance statement: To adapt to changing environments, animals often show plasticity in behaviours. Personality traits have been suggested to have close links with responsiveness, such that bolder and more aggressive individuals are less responsive to environmental stimuli. Using a mangrove killifish, our study showed that aggressiveness and boldness did not affect whether or how the fish responded to recent wins or losses. Competitive ability, however, played an important role; better competitors had greater decreases in aggressiveness after losing experiences, contrary to our expectations. These results together with the results of previous studies of the fish suggest that the fish’s responsiveness to winning-losing experiences could be sensitive to its internal conditions, the strength of the stimuli and potential floor/ceiling effects. This study also showed that individuals that are able to pay high metabolic costs are able to behave boldly and aggressively and to raise aggressiveness further.