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.

机体底层昼夜节律的行为表现所体现出的个体间可重复差异，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），对自由栖息的珍珠剃刀鱼（Xyrithchys novacula）的三种昼夜行为——觉醒时间、休息起始时刻与休息时长——进行了重复测量。此外，作为衡量鱼类日常活动的标准个性特征指标，每日移动距离也通过状态空间模型（State-Space Model）完成了重复评估。我们采用线性混合模型对上述四种行为特征的方差进行分解，并在控制环境协变量（实验年份、活动空间位置、鱼类体型与性别及其交互作用）的前提下，估算了可重复性得分（R）。个体间与个体内的方差分解结果显示，所有特征均存在显著的可重复性得分，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。我们将本次研究中昼夜型与鱼类个性特征间的相关性分解为个体间相关性与个体内相关性，结果未在个体间水平发现显著相关性。据此，我们提出将昼夜行为变异作为鱼类个性的独立维度，并将昼夜型及其影响的研究作为理解物种内鱼类行为多样性的全新研究视角。