Keeping in Sync with an Unpredictable Environment: Insights from Circadian Biology

Predictable environmental cues, such as daily and seasonal cycles of light and temperature, are integrated by circadian clocks in both plants and animals to coordinate metabolism, physiology, growth, development, and behavior with optimal times of day and year. This temporal coupling enables organisms to anticipate recurring environmental changes and maintain adaptive alignment between internal biological processes and the external environment. However, the accelerating pace of environmental change, including increased environmental variability and altered cue reliability, threatens this circadian alignment, potentially disrupting historically beneficial and adaptive relationships across taxa. In this review, we provide a cross-taxonomic synthesis of circadian regulation of output traits, highlighting conserved and taxa-specific mechanisms that rely on this synchronization. We provide context on how these timing processes may be reshaped or compromised in increasingly dynamic and less predictable environments.