title: Repeatability of circadian behavioural variation revealed in free-ranging marine fish.
abstract: 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 significantRs 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.
authors.affiliation: Instituto Mediterráneo de Estudios Avanzados , IMEDEA (CSIC-UIB) , C/ Miquel Marqués 21, 07190 Esporles, Illes Balears , Spain.
authors.forename: Josep
authors.identifier: 0000-0003-4385-9539
authors.initials: J
authors.lastname: Alós
authors.affiliation: Instituto Mediterráneo de Estudios Avanzados , IMEDEA (CSIC-UIB) , C/ Miquel Marqués 21, 07190 Esporles, Illes Balears , Spain.
authors.forename: Martina
authors.initials: M
authors.lastname: Martorell-Barceló
authors.affiliation: Instituto Mediterráneo de Estudios Avanzados , IMEDEA (CSIC-UIB) , C/ Miquel Marqués 21, 07190 Esporles, Illes Balears , Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Campos-Candela
keywords: acoustic tracking; behavioural syndrome; chronotypes; circadian clocks; hidden Markov models; repeatability