Data from: Characterizing behavioural ‘characters’: an evolutionary framework

Biologists often study phenotypic evolution assuming that phenotypes consist of a set of quasi-independent units that have been shaped by selection to accomplish a particular function. In the evolutionary literature, such quasi-independent functional units are called ‘evolutionary characters’, and a framework based on evolutionary principles has been developed to characterize them. This framework mainly focuses on ‘fixed’ characters, i.e. those that vary exclusively between individuals. In this paper, we introduce multi-level variation and thereby expand the framework to labile characters, focusing on behaviour as a worked example. We first propose a concept of ‘behavioural characters’ based on the original evolutionary character concept. We then detail how integration of variation between individuals (cf. ‘personality’) and within individuals (cf. ‘individual plasticity’) into the framework gives rise to a whole suite of novel testable predictions about the evolutionary character concept. We further propose a corresponding statistical methodology to test whether observed behaviours should be considered expressions of a hypothesized evolutionary character. We illustrate the application of our framework by characterizing the behavioural character ‘aggressiveness’ in wild great tits, Parus major.生物学家在开展表型进化研究时，通常假定表型由一系列准独立的功能单元构成，这些单元经选择塑造以实现特定功能。在进化生物学文献中，这类准独立的功能单元被称为进化性状（evolutionary characters），学界已建立基于进化原理的分析框架以对其进行表征。该框架主要聚焦于“固定性状”，即仅在个体间存在差异的性状。本文引入多水平变异的概念，由此将该框架拓展至易变性状，并以行为作为示范案例展开论述。我们首先基于原始的进化性状概念，提出行为性状（behavioural characters）的定义。随后我们详细阐述了，将个体间变异（参见“动物个性”）与个体内变异（参见“个体可塑性”）纳入该框架后，如何催生一系列针对进化性状概念的全新可检验预测。我们进一步提出了配套的统计方法，用以检验观测到的行为是否可被视为某一假设进化性状的表达形式。我们通过对野生大山雀（Parus major）的“攻击性”这一行为性状进行表征，展示了本框架的实际应用。