Tidal and diel orchestration of behaviour and gene expression in an intertidal mollusc

Y Schnytzer,O Levy,M Salmon-Divon,N Simon-Blecher,Y Achituv,J Li,H Waldman Ben-Asher,M E Hughes

doi:10.1038/s41598-018-23167-y

Abstract

Intertidal inhabitants are exposed to the 24-hour solar day, and the 12.4 hour rising and falling of the tides. One or both of these cycles govern intertidal organisms’ behaviour and physiology, yet little is known about the molecular clockworks of tidal rhythmicity. Here, we show that the limpet Cellana rota exhibits robust tidally rhythmic behaviour and gene expression. We assembled a de-novo transcriptome, identifying novel tidal, along with known circadian clock genes. Surprisingly, most of the putative circadian clock genes, lack a typical rhythmicity. We identified numerous tidally rhythmic genes and pathways commonly associated with the circadian clock. We show that not only is the behaviour of an intertidal organism in tune with the tides, but so too are many of its genes and pathways. These findings highlight the plasticity of biological timekeeping in nature, strengthening the growing notion that the role of ‘canonical’ circadian clock genes may be more fluid than previously thought, as exhibited in an organism which has evolved in an environment where tidal oscillations are the dominant driving force.

Highlights

Intertidal inhabitants are exposed to the 24-hour solar day, and the 12.4 hour rising and falling of the tides
Tidally-timed endogenous rhythms have evolved in most intertidal organisms[9]
As with the circadian clock, these endogenous rhythms persist for some time under constant conditions without tidal cues, can be entrained by appropriate stimuli, and are temperature compensated[10]

Summary

Introduction

Intertidal inhabitants are exposed to the 24-hour solar day, and the 12.4 hour rising and falling of the tides. As with the circadian clock, these endogenous rhythms persist for some time under constant conditions without tidal cues, can be entrained by appropriate stimuli, and are temperature compensated[10]. In order to establish the limpet’s rhythmicity under natural conditions we monitored a boulder with a population of C. rota over an extensive period of time (initially 15–20 individuals, up to 100 after further settlement; See limpet identification in materials and methods).

Results

Conclusion