Chronobiology of a southamerican subterranean rodent, the tuco-tuco

ODA GA; VALENTINUZZI VS

Montevideo

Jornada; XV Jornadas de la Sociedad Uruguaya de Biociencias-SUB; 2014

Sociedad Uruguaya de Biociencias-SUB

Discrepancies between data obtained in laboratory and in fi eld conditions have long been recognized in several biological studies, suggesting that a fundamental feature of the natural environment might not have been reproduced in the laboratory. This discrepancy can get quite dramatic dimensions in Chronobiology, with increasing evidence that some rodent species, characterized as nocturnal in the lab, are diurnal in the fi eld. Tuco-tucos (Ctenomys aff. knighti) are South-American, subterranean rodents that clearly display such phenomenon. It is known that the timing of activity is a function of how the circadian oscillator is synchronized by light/dark cycles. Then, our fi rst approach has been to verify whether the diurnal to nocturnal inversion might be due to the discrepant photic entrainments that result from the peculiar daily light exposure of these subterranean animals in the fi eld and from the artifi cial LD12:12 light regimens of the laboratory. Our second approach has been to verify factors that are downstream from the circadian oscillator. The ?thermoenergetic hypothesis? (Hut et al., 2013), associates timing differences to the discrepancy in energy demands between the fi eld and the ad-libitum food regimens of the lab. Subterranean rodents are excellent subjects to explore this proposition because their natural foraging activity involves intense underground digging, which demands high energy expenditure. All these investigations have been developed through an integrative chronobiological approach based on behavioral observations in semi-natural enclosures, photic entrainment experiments, mathematical modeling and metabolism/energetics measurements.