Abstract
Biological timing mechanisms are intrinsic to all organisms, orchestrating the temporal coordination of biological events through complex genetic networks. Circadian rhythms and developmental timers utilize distinct timekeeping mechanisms. This review summarizes the molecular basis for circadian rhythms in mammals and Drosophila, and recent work leveraging these clocks to understand temporal regulation in Caenorhabditis elegans development. We describe the evolutionary connections between distinct timing mechanisms and discuss recent insights into the rewiring of core clock components in development. By integrating findings from circadian and developmental studies with biochemical and structural analyses of conserved components, we aim to illuminate the molecular basis of nematode timing mechanisms and highlight broader insights into biological timing across species.