Effect of light and dark phase on dorsum colour and pattern in Hemidactylus sp. of Assam

The effects of exposure to dark and light conditions on dorsal colour and pattern were studied in five species of Hemidactylus from Assam. Marked changes were observed in the patterns as well as ground colour in all the species. House geckoes of the genus Hemidactylus inhabit outer walls of homes as well as forest fringes and as such are more likely to face anthropogenic stress. They rely on colour change as an adaptive measure. Most of them, away from light are extremely dark in their ground dorsum colouration. But, on being exposed to light their ground colour turns pale. There have been marked differences in pattern both dorsum and tail observed in light and dark condition. In the dark phase they mostly show dark pattern and markings. Such studies involving geckoes are important for identification of species as they may be misidentified otherwise.