Abstract One common theme of adaptive hypotheses for the existence of stable individual differences in behavior (personality) or persistent correlations among behaviors (behavioral syndromes) is an association between intrinsic state (e.g., body size, mass, metabolism) and the behavioral traits of interest. Empiricists are tasked with assessing whether there is an association between intrinsic state and behavior, but the statistical methods to appropriately quantify the among-individual correlation between intrinsic state and behavior have only recently become widely known. We conducted a multiyear study in wild mice of two Peromyscus species ( Peromyscus leucopus noveboracensis and Peromyscus maniculatus gracilis ) to assess the existence of stable individual differences in four different behaviors (presence of animal personality, as assessed by quantifying repeatabilities) and one measure of intrinsic state (body mass), the degree of association between these four behaviors (presence of behavioral syndromes), and the association of these behavioral traits with body mass using multivariate methods that allowed us to estimate the within-individual (residual) component and the among-individual component. We used standardized behavioral tests to measure struggle time (time spent struggling when removed from the trap) and exploration time (time spent exploring a novel surface) and used open-field trials to measure whether or not an individual entered the open field plus the total time it spent active in the open field. In P. leucopus , we assessed whether coarse but quick methods of assessing animal personality (struggle or exploration time) correlate with behavior using more in-depth estimates obtained by open-field trials. Additionally, we tested the ecological relevance of our personality measures by assessing their association with home range size in P. leucopus . In both species, struggle time, exploration time, and body mass were significantly repeatable and there was a significant among-individual correlation between struggle time and exploration time. However, in both species, there was no evidence for an among-individual correlation between our measure of intrinsic state (body mass) and personality traits. In one species ( P. leucopus ), we found that individuals that spent more time struggling or exploring a novel surface were also more likely to emerge into an open field and spent more time being active in an open field, but these four behavioral measures were not associated with home range size. Our results suggest among-individual correlation among these different behaviors but no among-individual correlation between behavior and intrinsic state. Significance statement Over the past 15 years, it has become clear that nonhuman animals exhibit “personalities”: some individuals consistently differ in their behavior, and there is limited flexibility in their behavior when they experience environmental change. Biologists have now been searching for why and how animal personalities exist and their ecological and evolutionary consequences. Some explanations have focused on how condition or “internal state” may cause variation in animal personalities. In this study, we show that two species of wild mice exhibit personalities and that their personality traits are associated with one another, in that mice that were less docile were also more active, exploratory, and bold. We then show that their personality traits were not linked with body mass, suggesting a lack of association between internal state and personality. Our results provide important insights into the causes of personality in nonhuman animals.

中文翻译：

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两种 Peromyscus 物种的人格和行为综合征：存在、缺乏状态依赖性以及与家庭范围大小缺乏关联

摘要 适应性假设的一个共同主题是行为（个性）中存在稳定的个体差异或行为之间的持续相关性（行为综合征）是内在状态（例如，身体大小、质量、新陈代谢）与感兴趣的行为特征之间的关联。 . 经验主义者的任务是评估内在状态和行为之间是否存在关联，但适当量化内在状态和行为之间的个体间相关性的统计方法直到最近才广为人知。我们对两种 Peromyscus 物种（ Peromyscus leucopus noveboracensis 和 Peromyscus maniculatus gracilis ）的野生小鼠进行了一项多年研究，以评估四种不同行为（动物个性的存在，通过量化可重复性来评估）和一种内在状态（体重）​​的测量，这四种行为之间的关联程度（行为综合征的存在），以及这些行为特征与体重的关联，使用多变量方法使我们能够估计个体内（残差）成分和个体间成分。我们使用标准化的行为测试来测量挣扎时间（从陷阱中取出时所花费的挣扎时间）和探索时间（探索新表面所花费的时间），并使用露天试验来衡量一个人是否进入了露天场地加上总它在空地上活跃的时间。在 P. leucopus 中，我们使用通过野外试验获得的更深入的估计来评估粗略但快速的评估动物个性（斗争或探索时间）的方法是否与行为相关。此外，我们通过评估它们与 P. leucopus 的家庭范围大小的关联来测试我们的个性测量的生态相关性。在这两个物种中，挣扎时间、探索时间和体重都具有显着的可重复性，并且挣扎时间和探索时间之间存在显着的个体间相关性。然而，在这两个物种中，没有证据表明我们对内在状态（体重）​​的测量与个性特征之间存在个体间相关性。在一个物种（ P. leucopus ）中，我们发现，花更多时间挣扎或探索新表面的人也更有可能进入开阔地带，并花更多时间在开阔地带活跃，但这四种行为指标与家庭范围大小无关。我们的结果表明这些不同行为之间存在个体间相关性，但行为与内在状态之间没有个体间相关性。意义声明 在过去的 15 年中，非人类动物表现出的“个性”已经很明显：一些个体的行为始终不同，当他们经历环境变化时，他们的行为灵活性有限。生物学家现在一直在寻找动物个性存在的原因和方式，以及它们对生态和进化的影响。一些解释集中在条件或“内部状态”如何导致动物个性的变化。在这项研究中，我们展示了两种野生老鼠表现出的个性，并且它们的个性特征彼此相关，因为不那么温顺的老鼠也更活跃、更具探索性和更大胆。然后，我们表明他们的个性特征与体重无关，这表明内部状态与个性之间缺乏关联。我们的研究结果为非人类动物的人格成因提供了重要的见解。和大胆。然后，我们表明他们的个性特征与体重无关，这表明内部状态与个性之间缺乏关联。我们的研究结果为非人类动物的人格成因提供了重要的见解。和大胆。然后，我们表明他们的个性特征与体重无关，这表明内部状态与个性之间缺乏关联。我们的研究结果为非人类动物的人格成因提供了重要的见解。