Nocturnal/Diurnal switches of a subterranean rodent in Lab and Field

ODA GA; VALENTINUZZI VS

Sao Paulo

Workshop; International Workshop on Organism-environment interactions: timing, plasticity and metabolic adjustments; 2018

Chronobiology studies using model species and manipulating artificial light/dark cycles have revealed the role of an endogenous, circadian clock, in determining if an organism is light-active or dark-active, in laboratory settings. While activity time dictated by a light/dark entrained circadian clock corresponds to the rigid component of activity timing, room for plasticity is conveyed by the masking mechanism, according to traditional Chronobiology views. Masking corresponds to a direct reaction of organisms to environmental stimuli such as temperature, humidity and predation risk levels. How these two mechanisms are still far from explaining nocturnality and diurnality in nature has been shown dramatically by animals that radically switch timing upon laboratory/field transference. The tuco-tuco (Ctenomys aff. knighti) is a South American desert subterranean rodent that displays such timing switches. Following traditional chronobiology views, we first investigated the hypothesis that different light exposure in lab and field could generate the switches, taking advantage of this species that inhabit the extreme photic environment of subterranean tunnels in nature. We also investigated potential masking factors that could differentially affect timing of activity in lab and field. More recently, however, we have been approaching the interface between chronobiology and energetics by investigating the hypothesis that switches in activity timing are a response to energetic challenges and that diurnality reduces thermoregulatory costs by consolidating activity to the warmest part of the day. This hypothesis has opened several new promising paths for widening chronobiological studies aimed at understanding timing in natural conditions.