Seasonal variation of thermal regulation in the tegu lizard Salvator merianae

• Grant number: 17/24656-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): May 01, 2018
• Effective date (End): December 31, 2018
• Field of knowledge: Biological Sciences - Physiology - Compared Physiology
• Principal Investigator: Kênia Cardoso Bícego
• Grantee: Diogo Renan Caporicci
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The tegu lizard Salvator merianae is unique among many other ectothermic reptiles because exhibits a pronounced seasonal cycle of hibernation during the dry mild winter in the southeastern Brazil, an ectothermy during the summer and a facultative endothermy during the reproductive season (spring). This reproductive endothermy was confirmed by higher heart rates (used as an estimative of metabolic rate) during the breeding season that were independent of ambient temperature. In addition, tegu lizards maintain their body temperature higher than ambient temperature only during this season. It is still unknown how tegu lizard regulates its body temperature during the breeding season. Therefore, our hypothesis is that: a) during the reproductive season, metabolic rate and ventilation will reduce much slower than ambient temperature, combined with peripheral vasoconstriction (reduction of surface temperature), mainly in the extremities (indicating heat conservation), especially in the females; and b) during autumn, the variables measured will change directly with changes in ambient temperature. To test this hypothesis, we will measure skin surface temperature, body temperature, pulmonary ventilation and oxygen consumption during controlled changes in ambient temperature in tegu lizards naturally acclimatized to spring (reproductive endothermy) and autumn (pre-hibernation season; ectothermy) seasons.