Dorsal colour pattern variation in Eurasian mountain vipers (genus Montivipera): A trade-off between thermoregulation and crypsis

Reptile colouration has long been studied as an example of adaptive evolution. Several functions have been proposed for variety of snake colour and pattern with the most common suggestions being camouflage, aposematism and thermoregulation. Montivipera raddei species complex shows a remarkable variation in dorsal colour pattern, but so far there has not been a comprehensive study performed on the adaptive nature of their colour pattern. The dorsal colour pattern of 111 specimens belonging to the M. raddei species complex, originating from 23 localities across its distribution range, were studied to explore intra and interspecific variation in the colour pattern. A generalized linear model analysis showed that there is a significant relationship between the dorsal colour pattern of Montivipera latifii, Montivipera raddei raddei and Montivipera raddei albicornuta, and the environmental factors of the habitat, including elevation, average annual temperature, average annual solar radiation, average annual precipitation, vegetation type and substrate colour. The results suggest that the dorsal colour pattern variation in the M. raddei species complex is affected by a complex trade-off between thermoregulation and crypsis.