Data from: Repeatability of circadian behavioural variation revealed in free-ranging marine fish

Repeatable between-individual differences in the behavioural manifestation of underlying circadian rhythms determine chronotypes in humans and terrestrial animals. Here, we have repeatedly measured three circadian behaviours, awakening time, rest onset and rest duration, in the free-ranging pearly razorfish, Xyrithchys novacula, facilitated by acoustic tracking technology and hidden Markov models. In addition, daily travelled distance, a standard measure of daily activity as fish personality trait, was repeatedly assessed using a State-Space Model. We have decomposed the variance of these four behavioural traits using linear mixed models and estimated repeatability scores (R) while controlling for environmental co-variates: year of experimentation, spatial location of the activity, fish size and gender and their interactions. Between- and within-individual variance decomposition revealed significant Rs in all traits suggesting high predictability of individual circadian behavioural variation and the existence of chronotypes. The decomposition of the correlations among chronotypes and the personality trait studied here into between- and within-individual correlations did not reveal any significant correlation at between-individual level. We therefore propose circadian behavioural variation as an independent axis of the fish personality, and the study of chronotypes and their consequences as a novel dimension in understanding within-species fish behavioural diversity.

内在昼夜节律的行为表现中所存在的可重复个体间差异，决定了人类与陆生动物的昼夜型（chronotypes）。本研究借助声学追踪技术与隐马尔可夫模型（Hidden Markov Models），对野外自由活动的珍珠剃刀鱼（Xyrithchys novacula）的三种昼夜节律行为——觉醒时间、休息起始时间与休息时长——进行了重复测量。此外，本研究采用状态空间模型（State-Space Model），对作为鱼类日常活动个性性状标准度量的日移动距离进行了重复评估。本研究通过线性混合模型（Linear Mixed Models）对这四种行为性状的方差进行分解，并在控制环境协变量（包括实验年份、活动空间位置、鱼体大小、性别及其交互作用）的前提下，估算了其重复力评分（R）。个体间与个体内的方差分解结果显示，所有性状均存在显著的重复力评分，这表明个体昼夜行为变异具有较高可预测性，且昼夜型确实存在。本研究将本次所研究的昼夜型与个性性状间的相关关系分解为个体间相关与个体内相关后，未发现个体间水平上存在显著相关。因此，本研究提出，昼夜行为变异可作为鱼类个性的独立维度，而对昼夜型及其影响的研究，将成为理解物种内鱼类行为多样性的全新视角。