A recurrent question in animal contests is whether individuals adopt a self or mutual assessment rule to decide to withdraw from a contest. However, many empirical studies fail to find conclusive support for one of these two possibilities. A possible explanation is that assessment strategies vary between individuals. In the contests of the orb-web spider Trichonephila clavipes, males perform a vibrational display on webs that may escalate to physical contact. Since all individuals perform the vibrational phase and only some of them escalate, we proposed two hypotheses: 1) all individuals perform mutual assessment during the vibrational phase, or 2) some individuals that do not escalate adopt self-assessment, while individuals that escalated adopt mutual assessment. To evaluate these hypotheses, we investigated the relationship between the duration of the vibrational phase and frontal leg length (a proxy of male fight capacity) of loser and winner males in contests that escalated and did not escalate to the physical contact phase. We found a non-significant relationship between duration and losers leg length for both contests that escalate and did not escalate. While we found a positive relationship between duration and winners leg length, particularly in contests that did not escalate. These results do not provide support for mutual assessment or for a mix of different assessment rules among individuals. We suggest that in T. clavipes, the dynamics of the vibrational phase may be explained by two different contest strategies (opponent-only assessment or size-based aggressiveness) that are dependent on intruder motivation to escalate.

中文翻译：

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振动攻击：雄性蜘蛛在比赛展示期间执行不寻常的评估策略

动物竞赛中经常出现的一个问题是，个体是否采用自我评估规则或相互评估规则来决定退出竞赛。然而，许多实证研究未能为这两种可能性之一找到决定性的支持。一个可能的解释是评估策略因人而异。在球网蜘蛛 Trichonephila clavipes 的竞争中，雄性在网上进行振动展示，可能升级为身体接触。由于所有个体都进行振动阶段并且只有部分个体升级，我们提出两个假设：1）所有个体在振动阶段进行相互评估，或2）一些不升级的个体采取自我评估，而升级的个体则采取自我评估。相互评价。为了评估这些假设，我们研究了在升级和未升级到身体接触阶段的比赛中失败者和获胜者男性的振动阶段持续时间与额腿长度（男性战斗能力的代表）之间的关系。我们发现，无论是升级还是未升级的比赛，持续时间和失败者腿长之间都没有显着关系。虽然我们发现持续时间和获胜者腿长之间存在正相关关系，特别是在没有升级的比赛中。这些结果并不支持相互评估或个人之间不同评估规则的混合。我们认为，在 T. clavipes 中，振动阶段的动态可以通过两种不同的竞争策略（仅对手评估或基于体型的攻击性）来解释，这两种策略取决于入侵者升级的动机。