From harsh deserts to frozen mountaintops, animals have found a way to thrive in the many climatic niches found on our planet. As species adapt to new thermal environments, they have evolved molecular and physiological mechanisms for survival, but also changes in temperature and humidity preference that reflect the conditions of their new habitat. However, we know little about how animal behavior evolves, and how differences in temperature sensation underlie these behavioral adaptations.

Insects rely on their thermosensory system to sense and respond to external temperature: an array of specialized sensory neurons equipped with molecular heat receptors that detect changes in external temperature and send signals to the brain, where this information is then processed to guide behavior.

In this research, we discovered that at least two distinct neurobiological mechanisms drive the evolution of temperature preference behavior in flies of the genus Drosophila. Fly species from mild climates (D. melanogaster and D. persimilis) avoid heat, and we show that changes in the sensitivity of their heat receptor adjust avoidance behavior to match the conditions of their natural habitats. By contrast, the desert-adapted fly D. mojavensis is actively attracted to heat, mediated by the same heat receptor. Instead, this attraction behavior is driven by specific changes in how heat signals are processed in the brain.