Data from: Functional relations between body mass and risk-taking behavior in wild great tits

Natural selection often favors particular combinations of
functionally-related traits, resulting in adaptive phenotypic integration.
Phenotypic integration has been proposed as a potential mechanism
explaining the existence of repeatable among-individual differences in
behavior (i.e., animal personality). In this study, we investigated
patterns of covariation between morphology and behavior in a population of
free-living great tits (Parus major) monitored for seven years. In
particular, we aimed to disentangle the effect of structural size versus
body condition on risk-taking behavior. To do so, we repeatedly quantified
multiple morphological (body mass, wing, tarsus, and bill length) and
behavioral traits (aggressiveness and exploration) in 742 individual
males. Structural equation modelling (SEM) allowed us to test causal a
priori hypothesized relationships between the different morphological and
behavioral traits. Our best-fitting SEM model supported the existence of a
behavioral character, “risk-taking behavior” that covaried simultaneously
with the latent variable “body size”, and “body condition”. Our findings
thus demonstrate that an individual’s morphological and behavioral traits
represent expressions of an integrated phenotype, suggesting a role for
phenotypic integration in generating animal personality in a wild bird
population.

自然选择通常倾向于保留功能相关性状的特定组合，从而形成适应性表型整合（phenotypic integration）。表型整合被认为是解释行为中可重复的个体间差异（即动物个性）存在的潜在机制。本研究对一个连续监测七年的野生大山雀（Parus major）种群，探究了形态与行为之间的协变模式。具体而言，我们旨在区分结构大小与身体状况对风险承担行为的影响。为此，我们对742只雄性个体的多项形态性状（体重、翼长、跗骨长和喙长）和行为性状（攻击性与探索性）进行了重复量化。结构方程模型（Structural Equation Modelling, SEM）使我们能够检验不同形态性状与行为性状之间的先验假设因果关系。我们拟合最优的SEM模型支持存在一个名为“风险承担行为”的行为特征，该特征与潜变量（latent variable）“结构大小”和“身体状况”同时存在协变关系。因此，我们的研究结果表明，个体的形态性状与行为性状是整合表型的体现，提示表型整合在野生鸟类种群中动物个性的形成中发挥作用。