Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

R. A. Hut*, D. G. M. Beersma

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

117 Citations (Scopus)
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Abstract

Virtually all species have developed cellular oscillations and mechanisms that synchronize these cellular oscillations to environmental cycles. Such environmental cycles in biotic (e. g. food availability and predation risk) or abiotic (e. g. temperature and light) factors may occur on a daily, annual or tidal time scale. Internal timing mechanisms may facilitate behavioural or physiological adaptation to such changes in environmental conditions. These timing mechanisms commonly involve an internal molecular oscillator (a 'clock') that is synchronized ('entrained') to the environmental cycle by receptor mechanisms responding to relevant environmental signals ('Zeitgeber', i.e. German for time-giver). To understand the evolution of such timing mechanisms, we have to understand the mechanisms leading to selective advantage. Although major advances have been made in our understanding of the physiological and molecular mechanisms driving internal cycles (proximate questions), studies identifying mechanisms of natural selection on clock systems (ultimate questions) are rather limited. Here, we discuss the selective advantage of a circadian system and how its adaptation to day length variation may have a functional role in optimizing seasonal timing. We discuss various cases where selective advantages of circadian timing mechanisms have been shown and cases where temporarily loss of circadian timing may cause selective advantage. We suggest an explanation for why a circadian timing system has emerged in primitive life forms like cyanobacteria and we evaluate a possible molecular mechanism that enabled these bacteria to adapt to seasonal variation in day length. We further discuss how the role of the circadian system in photoperiodic time measurement may explain differential selection pressures on circadian period when species are exposed to changing climatic conditions (e. g. global warming) or when they expand their geographical range to different latitudes or altitudes.

Original languageEnglish
Pages (from-to)2141-2154
Number of pages14
JournalPhilosophical Transactions of the Royal Society of London. Series B: Biological Sciences
Volume366
Issue number1574
DOIs
Publication statusPublished - 27-Jul-2011

Keywords

  • circadian system
  • photoperiodism
  • cyanobacteria
  • seasonal adaptation
  • suprachiasmatic nucleus
  • chronobiology
  • RAPID CLIMATE-CHANGE
  • CYANOBACTERIAL CIRCADIAN CLOCKWORK
  • MOUSE SUPRACHIASMATIC NUCLEUS
  • PHODOPUS-SUNGORUS-SUNGORUS
  • EUROPEAN GROUND-SQUIRREL
  • PITCHER-PLANT MOSQUITO
  • SYRIAN-HAMSTER ALTERS
  • PARS TUBERALIS
  • KAIC PHOSPHORYLATION
  • MELATONIN SYNTHESIS

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