Influence of prior contest experience and level of escalation on contest outcome
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An individual’s contest history can have a significant effect on their probability of winning a future contest. These winner–loser effects are likely to be mediated by the level of escalation in a contest, although this is rarely considered in the contest literature. We staged contests between size-matched male water skinks (Eulamprus quoyii) in a tournament design to investigate how prior contest success indirectly affected contest outcome through its effects on contest behavior. Moreover, we predicted that the effect of behavioral traits on contest outcome would depend on the level of escalation reached by contestants (non-escalated versus escalated contests). Contest initiation was the best predictor of contest outcome in both non-escalated and escalated contests, and whether an individual initiated a contest depended on prior contest experience. Prior winners were more likely to initiate subsequent aggressive encounters, and by doing so, initiators had an 88 % probability of winning compared to non-initiators in non-escalated contests. However, this effect was mediated by the level of escalation. Initiators in escalated contests had only a 59 % probability of winning compared to non-initiators. These results suggest that the strength of the effect of prior contest experience on behavioral traits varies across contest stages and is consistent with the hypothesis that prior contest experience alters an individual’s perception of its own fighting ability. Our study highlights the importance of considering the level of contest escalation when examining winner–loser effects in predicting contest outcome.
Our results show that the effect of prior contest experience on contest initiation varies depending on the level of escalation reached by the contestants. We emphasize the importance of considering the level of contest escalation when examining the influence of prior contest experience on contest outcome.
KeywordsContest history Lizard Contest initiation Contest escalation Bradley-Terry model Tournament design
We would like to thank the two anonymous reviewers for their constructive feedback on the earlier version of this manuscript. We are grateful for David Firth and Heather Turner for their statistical advice with the BT model. We would like to also thank the numerous members of the Lizard Lab that assisted us with lizard collection, husbandry, and experimental setup.
Compliance with ethical standards
DWAN was supported by an Australian Research Council (DECRA DE150101774), and this work was also supported by Macquarie University and a Discovery grant (DP130102998) awarded by the Australian Research Council to MJW.
Conflict of interest
The authors declare that they have no conflict of interest.
All protocols for this study were in accordance with the ethical standards of the Macquarie University Animal Ethics Committee (ARA 2014/036). A scientific permit for this study was granted by the New South Wales National Parks and Wildlife Service, Office of Environment and Heritage (SL100328).
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