Plasticity in daily timing of behavior: Causes and consequences

Vincent van der Vinne

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Circadian clocks control daily rhythms in physiology and behavior and thereby allow organisms to anticipate daily changes in their environment. Although most small mammals are strictly nocturnal under standard laboratory conditions, studies in more natural environments show that substantial plasticity exists in the daily timing of behavior. Mammals that are otherwise nocturnal choose to switch temporal niche and become diurnal in response to adverse conditions. This thesis investigates the causes and consequences of that plasticity in daily timing of behavior.
A literature review reveals cold and hunger as important environmental factors responsible for temporal niche switches. Based on this observation we propose the circadian thermo-energetics hypothesis, which predicts that diurnality is associated with energetic savings. Controlled laboratory studies show that mice use the plasticity of their circadian system in response to changes in their energetic state and become diurnal in response to cold and hunger. This diurnality is supported by phase advances of circadian clocks in peripheral organs but not the main clock in the suprachismatic nucleus. Quantification of the energy expenditure of mice shows that diurnality results in a 6-10% reduction in daily energy expenditure. Under natural conditions, these energetic benefits will have to be balanced against other consequences of temporal niche switching (e.g. predation risk). Indeed, when tested under semi-natural conditions, temporal niche switching is observed in mice when food availability and perceived predation risk are manipulated. Overall, this thesis identifies plasticity in daily timing of behavior as an adaptive response to changes in the environment.
Originele taal-2English
KwalificatieDoctor of Philosophy
Toekennende instantie
  • Rijksuniversiteit Groningen
Begeleider(s)/adviseur
  • Hut, Roelof, Supervisor
  • Beersma, Dominicus, Supervisor
  • Visser, Marcel, Beoordelingscommissie
  • van Marken Lichtenbelt, Wouter, Beoordelingscommissie
  • Barnes, B.M., Beoordelingscommissie, Externe Persoon
Datum van toekenning18-sep.-2015
Plaats van publicatie[Groningen]
Uitgever
StatusPublished - 2015

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