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.学界已开展大量研究，旨在阐释动物个性（animal personality）的重要性，尤其聚焦探索行为性状的稳定个体差异与其他潜在性状之间的潜在关联。“个性-生产力假说（personality-productivity hypothesis）”提出，行为与生活史性状的个体差异之间存在关联：即生产力较高（生长迅速、繁殖频繁）的个体，通常表现出更高的活跃度、攻击性与大胆性（boldness），这类性状可能介导生长-存活权衡（growth-mortality trade-offs）效应。本研究在可控实验室环境下，以普通卷甲虫（<i>Armadillidium vulgare</i>，俗称潮虫）为研究对象，检验了大胆性（以从防御蜷缩姿态舒展的潜伏期为测量指标）、生长速率与存活率三者间的关联。本研究团队对94个个体每周开展1次测量，持续18周，同步记录其大胆性与体质量数据，总计获得1168组配对测量值；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、大胆性可塑性（plasticity in boldness）与生长速率均存在显著变异，但本研究未发现大胆性或大胆性可塑性与生长速率存在关联。然而，本研究发现舒展潜伏期与体质量之间存在显著的个体间正相关，这在个体层面支持了资产保护原理（asset protection principle）：即体型较大的个体更为害羞，体型较小的个体则更大胆。与之相对，舒展潜伏期与体质量之间的个体内相关则呈负值，这表明二者的关联可塑性（correlated plasticity）可能响应其他状态变量（如代谢速率、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，但确证了大胆性与体质量之间存在状态-行为关联。