Elian et al.

Extensive research has been devoted towards understanding the significance of animal personality, particularly in exploring potential links between consistent individual differences in behavioural traits and other underlying traits. The ‘personality-productivity’ hypothesis suggests a link between behaviour and individual differences in life-history traits, whereby individuals that are highly productive (grow fast, reproduce often) are expected to be more active, aggressive and bold, traits which are likely to contribute to growth-mortality trade-offs. Here, we tested the relationship between boldness (measured as latency to deconglobate from a defensive posture), growth rate, and survival in pill bugs (<i>Armadillidium vulgare</i>) in a controlled lab environment. We concurrently measured boldness and body mass on 94 individuals, once per week for 18 weeks, for a total of 1,168 paired measurements, and analysed the data using bivariate random regression model which accounted for among- and within-individual covariance between mass, growth and boldness. Despite significant variation in boldness, plasticity in boldness and growth rate, we found that neither boldness nor plasticity in boldness were correlated with growth rate. However, we found a significant positive among-individual correlation between latency to deconglobate and body mass, which support the asset protection principle at the among-individual level (i.e., large individuals were shy, small individuals were bold). By contrast, the within-individual correlation between latency to deconglobate and body mass was negative, suggesting the role of correlated plasticity in response to another state variable (e.g., metabolic rate, hydration levels). Overall, the study provides no evidence for the personality-productivity hypothesis, but does show evidence of state-behaviour relationships between boldness and body mass.

大量研究致力于解析动物个性的重要意义，尤其聚焦于探索行为特质的稳定个体差异与其他内在特质间的潜在关联。"个性-生产力"假说（personality-productivity hypothesis）提出，行为与生活史特质的个体差异存在关联：即生产力较高（生长快速、繁殖频繁）的个体往往更活跃、具攻击性且大胆，这些特质可能促成生长-存活权衡（growth-mortality trade-offs）。本研究在可控实验室环境中，检验了潮虫（Armadillidium vulgare）的大胆性（boldness，其测量指标为从防御卷球状姿态退散的潜伏期）、生长速率与存活率之间的关系。我们对94个个体每周开展一次大胆性与体质量的同步测量，持续18周，总计获得1168组配对测量数据，并采用双变量随机回归模型（bivariate random regression model）分析数据，该模型可考量体质量、生长速率与大胆性之间的个体间及个体内协方差。尽管大胆性、大胆性的可塑性与生长速率均存在显著变异，但我们未发现大胆性或大胆性可塑性与生长速率存在相关性。然而，我们在个体间层面发现了退散潜伏期与体质量间显著的正相关关系，这在个体间水平上支持了资产保护原则（asset protection principle）：即体型较大的个体更羞怯，体型较小的个体更大胆。与之相对，个体内层面的退散潜伏期与体质量间呈负相关，这表明二者的可塑性关联可能响应于其他状态变量（如代谢率、水化水平）。总体而言，本研究未为"个性-生产力"假说提供支持证据，但确实揭示了大胆性与体质量之间存在状态-行为关联。