Aggression is one of the most frequently studied behavioural traits across a wide range of taxa; however, most studies evaluate aggressive behaviour in a social context, in which aggressive interactions between conspecifics are motivated by resource control (offensive or social aggression). However, in an antipredator context, the primary role of aggression is defence (defensive or antipredator aggression). Although the neuroendocrinology of antipredator aggression is often studied in domesticated and laboratory animals, how environment and individual state affect this behavioural trait in the wild is largely unknown. Here, by conducting a manipulative experiment, we tested whether (i) consistent between-individual differences (i.e. animal personality) are present in antipredator aggression in adult male Carpetan rock lizards (Iberolacerta cyreni) and (ii) short-term environmental changes (presence vs. absence of predator cues) and differences in individual state (body length, head size, hind limb length) affect individual mean behaviour (i.e. behavioural type). We found moderate-high repeatability in antipredator aggression (willingness to bite a human), indicating the presence of animal personality in this behavioural trait. Lizards were on average more defensive in the presence of predator cues; furthermore, short-legged males showed higher antipredator aggression than long-legged males in the presence of predator cues, probably as an attempt to balance their decreased escape speed. Larger (~ older) males were more defensive than smaller ones, probably due to their increased fighting ability. We conclude that antipredator aggression is an important part of an individual’s behavioural repertoire and its expression is driven by both environmental situation and individual state. Antipredator/defensive aggression is not the primary antipredatory response; however, when other ways of escape are not possible, actually hurting the predator could be the only way of survival. While this behaviour obviously has substantial effects on fitness, it is severely understudied compared to social/offensive aggression. In a manipulative experiment, we found that there are consistent between-individual differences in antipredator aggression (i.e. willingness to bite during handling) of adult male Carpetan rock lizards (Iberolacerta cyreni), supporting the presence of animal personality and suggesting that this behavioural trait might respond to natural selection. Furthermore, short-term environmental variation (i.e. presence vs. absence of predator cues) in interaction with individual state affected antipredator aggression of individuals, emphasising the ecological and evolutionary relevance of this behaviour.

中文翻译：

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不会不战而降：Carpetan 岩蜥蜴中反捕食者防御性攻击性人格的状态和环境依赖性

攻击性是广泛分类群中最常研究的行为特征之一。然而，大多数研究评估的是社会环境中的攻击行为，其中同种之间的攻击性互动是由资源控制（攻击性或社会攻击性）驱动的。然而，在反捕食者的背景下，侵略的主要作用是防御（防御或反捕食者的侵略）。尽管经常在家养和实验室动物中研究抗捕食者攻击的神经内分泌学，但环境和个体状态如何影响野外的这种行为特征在很大程度上是未知的。在这里，通过进行操纵性实验，我们测试了（i）个体间差异是否一致（即 动物个性）存在于成年雄性 Carpetan 岩蜥 (Iberolacerta cyreni) 和 (ii) 短期环境变化（存在与不存在捕食者线索）和个体状态差异（体长、头部大小、后肢）长度）影响个体平均行为（即行为类型）。我们发现反捕食者的侵略性（咬人的意愿）具有中等高度的可重复性，表明这种行为特征中存在动物个性。在有捕食者线索的情况下，蜥蜴平均更具防御性；此外，在存在捕食者线索的情况下，短腿雄性比长腿雄性表现出更高的反捕食者侵略性，这可能是为了平衡它们降低的逃跑速度。较大（〜年长）的雄性比较小的雄性更具防御性，可能是因为他们增加了战斗力。我们得出的结论是，反捕食者的侵略是个人行为库的重要组成部分，其表达受环境状况和个人状态的驱动。反捕食者/防御性攻击不是主要的反捕食反应；然而，当其他方式无法逃脱时，实际上伤害捕食者可能是唯一的生存方式。虽然这种行为显然对健康有重大影响，但与社交/攻击性攻击相比，它的研究严重不足。在一项操纵性实验中，我们发现成年雄性 Carpetan 岩蜥 (Iberolacerta cyreni) 的抗捕食者攻击性（即在处理过程中咬人的意愿）存在一致的个体差异，支持动物个性的存在，并表明这种行为特征可能对自然选择有反应。此外，与个体状态相互作用的短期环境变化（即存在与不存在捕食者线索）影响了个体的反捕食者侵略，强调了这种行为的生态和进化相关性。