title: In search of a temporal niche: environmental factors.
abstract: Time as an ecological niche variable or "temporal niche" can be defined in the context of the most prominent environmental cycles, including the tidal cycle, the lunar day and month, the solar day, and the earth year. For the current review, we focus on the 24-h domain generated through the earth's rotation around its axis (solar day). The daily environmental cycles of light and temperature are a dominant ecological factor generating a variety of adaptations among animals. In this review, we describe these adaptations with a special focus on the visual system and on the adaptive plasticity of activity patterns. Our goals are: (1) Underscore the importance of the 24-h time axis as critical variable in the ecological niche. (2) Highlight cases of temporal niche switches at the evolutionary timescale (phylogenetic level). (3) Review temporal niche switching within an individual's lifespan. (4) Evaluate possible underlying mechanisms for temporal niche switching. (5) Describe a new hypothesis of circadian thermoenergetics which may explain several cases of temporal niche switching in mammals. With this, we hope to inspire experiments under natural conditions or more complex laboratory environments, aimed to reveal environmental factors and mechanisms underlying specific temporal programs.
authors.affiliation: Chronobiology unit, Center for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands. Electronic address: r.a.hut@rug.nl.
authors.forename: Roelof A
authors.initials: RA
authors.lastname: Hut
authors.affiliation: Department of Zoology, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Noga
authors.initials: N
authors.lastname: Kronfeld-Schor
authors.affiliation: Chronobiology unit, Center for Behaviour and Neurosciences, University of Groningen, Groningen, The Netherlands.
authors.forename: Vincent
authors.initials: V
authors.lastname: van der Vinne
authors.affiliation: Department of Biology and Program of Neurobiology and Behavior, University of Washington, Seattle, USA.
authors.forename: Horacio
authors.initials: H
authors.lastname: De la Iglesia
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D004777:Environment; D006801:Humans; D017440:Photoperiod