Entraining to the polar day: Circadian rhythms in arctic ground squirrels

Cory T. Williams, Brian M. Barnes, Lily Yan, C. Loren Buck

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Circadian systems are principally entrained to 24 h light-dark cycles, but this cue is seasonally absent in polar environments. Although some resident polar vertebrates have weak circadian clocks and are seasonally arrhythmic, the arctic ground squirrel (AGS) maintains daily rhythms of physiology and behavior throughout the summer, which includes 6 weeks of constant daylight. Here, we show that persistent daily rhythms in AGS are maintained through a circadian system that readily entrains to the polar day yet remains insensitive to entrainment by rapid light-dark transitions, which AGS generate naturally as a consequence of their semi-fossorial behavior. Additionally, AGS do not show 'jet lag', the slow realignment of circadian rhythms induced by the inertia of an intrinsically stable master circadian clock in the suprachiasmatic nucleus (SCN). We suggest this is due to the low expression of arginine vasopressin in the SCN of AGS, as vasopressin is associated with inter-neuronal coupling and robust rhythmicity.

Original languageEnglish (US)
Pages (from-to)3095-3102
Number of pages8
JournalJournal of Experimental Biology
Issue number17
StatePublished - Sep 1 2017


  • Biologging
  • Body temperature
  • Chronobiology
  • Jet lag
  • Polar vertebrates
  • Urocitellus parryii
  • Zeitgeber

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science


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