Changed substrate preferences shown by Fringe-toed Lizards, Acanthodactylus scutellatus, from Kuwait’s Al-Burgan oil field (Reptilia: Lacertidae)

Abstract

Oil pollution in desert locations in Greater Al-Burgan oil fields of Kuwait generated by the 1990 Gulf war has changed field behaviour and morphology of the Fringe-toed Lizard Acanthodactylus scutellatus (Audouin, 1827). Lizards from the dark ‘tar mat’ locations are notably darker in colour than those from the control sites. Consequently, A. scutellatus collected from ‘tar mat’ and counterparts from lighter control sites were compared in laboratory studies where the lizards could choose between a dark and a light side of an enclosure. The former lizards showed a clear preference for darker substrates whereas the latter clearly preferred the light substrate. Dark lizards on tar mat have more effective crypsis but also some advantages in terms of solar gain (surprisingly, reptiles from tar mat sites are generally larger than counterparts from uncontaminated sites). It is uncertain whether the presence of dark substrates for more than a decade (this study was conducted in 2003) has resulted in a selection of morphologically dark sand lizards with a preference for dark surfaces or whether these reptiles simply use their skin chromatophores to adapt to different surfaces but show a preference for substrates similar to their body colouration. .