Physiological aspects are sensitive to fluctuations in body temperature, specially in ectothermic animals. Studies suggest coadaptation between body temperature during activity and optimal temperature for performance. Nocturnal lizards, despite being active in low temperatures, have optimal temperature for locomotor performance similar to the one described for diurnal lizards. Thus, the coadaptation quoted is not observed. The handicap in the locomotor performance imposed by the low temperature during the night is partially compensated by a low energetic cost of locomotion, that can be associated with an increase in the activity of different enzymes. The present project aims to apply a comparative approach to investigate the evolution of physiological aspects, with specific focus in enzymatic thermal sensitivity, associated to the acquisition of nocturnal habit by lineages of Gymnophthalmidae lizards. The general hypotheses to be tested are: 1) the activity of metabolic and digestive enzymes in nocturnal lizards is higher at lower temperatures, when compared with diurnal species; and 2) the adaptation of the enzymatic activity to lower temperature in nocturnal species occurred by an adaptive evolutionary process and not by reversible thermal acclimation. Three nocturnal and two diurnal species of Gymnophthalmidae and an external group (diurnal) will be used. The hypotheses will be tested using enzymatic activity assays performed at different temperatures, from muscles, brain and intestine of animals directly brought from the field and animals allowed to acclimate in the laboratory to different temperatures. The comparative analysis of the data will allow mapping patterns associated to the evolution of the nocturnal habit in species of Gymnophthalmidae lizards.
News published in Agência FAPESP Newsletter about the scholarship: