CONICET | Buscador de Institutos y Recursos Humanos

Plasticity in circadian rhythmicity is becoming a subject of increasing interest for chronobiologists. Switches from nocturnality in the lab to diurnality in the field, recently reported for many rodent species, are sticking examples of rhythmicity plasticity. The subterranean rodent tuco-tuco (Ctenomys aff. Knight) is among the species which display such switches, being nocturnal in the standard lab conditiones but displaying a significant amount of activity during the light hours of the day in the field. Our group has been studying this phenomenom by collecting data, for several years, on physiological (body temperature) and bahavioral (light exposure and locomotor activity) rhythms of tuco-tucos in semi-natural enclosures and tracking their changes when the animals are transferred to lab. This approach has revealed that, while photic entrainment to the light-dark cycle is similar in both field and the lab, the variety of rhythmic patterns displayed in the field is even greater than we expected. This suggest an interaction of the circadian system with a wide set of biotic and abiotic factors that differ between the lab and the field. We have focused mainly on conditiones related to the daily energy budget challenges. For tuco-tucos, energetic challenges are much greater in the field than in the lab, since this herbivorous rodent forage by intense digging, in a semiarid habitat where vegetation is sparse and there are great daily changes in Ta. Noteworthy, these conditions have been changing in the last years, in their natural habitat in Argentina, especially with the increase in rainfall. Increase in the plasticity of rhythmic patterns have been registered along these years and investigation of this phenomenom may provide insights into the role of environmental changes on timing of activity and physiological changes.

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