Tegu lizards warm up for mating

Despite their cold-blooded reputation, tegu lizards boost their body heat while on the prowl for a mate, biologists report online January 22 in Science Advances.

Like other ectotherms, tegu lizards (Salvator merianae) in South America draw heat from their environment, sunning themselves in spring and summer and hibernating in autumn and winter. Upon waking from their seasonal slumber, the males 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, both males and females stayed significantly warmer (by up to 10 degrees Celsius) than the air. The lizards maintained a significant temperature difference for up to eight days without the help of sunlight.

During mating season, researchers saw a rise in morning 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 researchers suspect. The work is consistent with the idea that reproduction played a role in the evolution of warm-bloodedness.