Biological timekeeping in polar environments: lessons from terrestrial vertebrates

Area of Science:

• Chronobiology
• Polar Biology
• Animal Physiology

Background:

• Polar regions experience extreme seasonal variations in light exposure, with prolonged periods of daylight and darkness.
• Reduced daily amplitude of solar illumination and unique spectral composition challenge biological timekeeping mechanisms.
• Understanding polar biological timekeeping is crucial for comprehending evolutionary adaptations in extreme environments.

Purpose of the Study:

• To investigate the functional and mechanistic aspects of biological timekeeping in polar environments.
• To determine the extent to which circadian timekeeping is maintained and how it's influenced by physiology and life history.
• To explore how polar solar illumination affects daily and seasonal timekeeping and light entrainment.

Main Methods:

• Comparative analysis of species' physiological and bioenergetic constraints.
• Observation of photic cue influence on circadian synchrony in Arctic species.
• Assessment of reliance on innate circannual timer mechanisms versus photic cues.

Main Results:

• Circadian synchrony can be maintained by photic cues in some Arctic species, even during polar summer.
• Timer systems in polar species may adapt to exploit specific polar light cues.
• Temporal organization in some species may shift away from circadian clock dominance.
• Reliance on circannual timers varies, reflecting differing access to year-round photic cues.

Conclusions:

• Polar chronobiology offers a valuable model for studying the adaptive evolution of daily and seasonal timekeeping.
• Species-specific adaptations in physiology and life history dictate responses to polar light regimes.
• Significant opportunities exist for further research into the mechanisms and functions of polar biological timekeeping.