In 'hot' pursuit: exploring the evolutionary ecology of labial pits in boas and pythons

The evolution of thermoreception in animals, particularly that of infrared (IR)-sensing pits in boas, pythons and pit vipers, is a fascinating area of sensory ecology. While numerous studies have focused on the molecular mechanisms of IR sensing in snakes, the broader ecological and evolutionary significance remains less explored. In this study, we examined the origins and evolutionary consequences of labial pits in boas and pythons using phylogenetic comparative methods. We analysed how various ecological and biological factors-such as hunting mode, diet, habitat, body size and biome-were correlated with the presence of pits, and whether this adaptation influenced diversification rates. Our findings revealed that labial pits evolved multiple times and showed strong associations with an arboreal habitat and endothermic diet, but we did not find a significant correlation between pits and hunting mode or any other ecological traits. Moreover, lineages with pits did not exhibit higher diversification rates. This research provides new insights into the eco-evolutionary role of heat-sensing pits, suggesting that the emergence of labial pits might have acted as a key innovation, significantly affecting the evolution of habitat use patterns and prey preference for pythons and boas.