Despite their cold-blooded reputation, tegu lizards boost their body heat while on the prowl for a mate, biologists report January 22 in Science Advances.
Like other ectotherms, South American tegu lizards (Tupinambis merianae) draw heat from their environment, sunning themselves in spring and summer and hibernating in autumn and winter. Upon waking from their seasonal slumber, the reptiles search for a mate.
Researchers from Canada and Brazil monitored body temperature in a group of captive lizards through these seasonal shifts. At night during mating season, their bodies stayed significantly warmer (by up to 10 degrees Celsius) than the air. The lizards maintained this temperature difference for up to eight days without the help of sunlight.
Researchers saw a steady rise in heart rate and body temperature, suggesting that tegu lizards have an unusual ability to produce and sustain body heat. Though the exact mechanism remains unclear, metabolic changes that come with reproduction could drive up the lizards’ body temperatures, the researcher suspect. The work lends credence to the idea that reproduction played a role in the evolution of warm-bloodedness.