The role of skin colour in Madagascan herpetofauna

Madagascan herpetofauna

Imitating dead leaves – Uroplatus ebenaui, photographed by Randall Morrison

A recent study into the ecological significance of skin colour among groups of lizards in northwestern Madagascar has focused on the roles of matching backgrounds (camouflage) and communication within populations.

Madagascar is widely considered one of the world’s most important biodiversity hotspots. Not only are there high levels of endemism (popularly exemplified by lemur and chameleon diversity) but a continuing loss of habitat as a result of deforestation. The Mahamavo ecosystem of northwest Madagascar has been identified as a transition zone between northern and western fauna making it particularly interesting in terms of its overall biodiversity. These high levels of diversity and exceptional abundance of herpetofauna make this an ideal location for the study of skin colour and its ecological significance in lizards.

Camouflage and communication

Two of the most significant uses of colour are for crypticity (the use of colour and pattern as camouflage) and signalling (communication between individuals within a population). The three species of Leaf-tail geckos at Mahamavo are excellent at background matching: one imitates dead leaves (Uroplatus ebenaui); a second imitates twigs (Uroplatus guentheri); and a third is a bark mimic (Uroplatus henkeli). The two species of chameleons also found at this site (Furcifer angeli and Furcifer oustaleti) use colouration primarily for the communication of social status rather than camouflage, which is a common misconception.

Studying herpetofauna in Madagascar

Dissertation students using the Jaz spectrometer, photograph by Randall Morrison

Reflectance spectrometry is a useful technique for analysing colour differences in lizard skin. We use a Jaz spectrometer from Ocean Optics in the field to measure the percent reflectance of specific wavelengths using a known light source and employing a combined fibre optic cable for both illumination and detection. This is an improvement over using non-standardised photographic techniques and has proven to be a useful tool in measuring colour differences between males and females within and even between species of both geckos and chameleons.

In the future this methodology can be used to investigate other ecological uses of colour in other groups of lizards as well. Continuing habitat modification will dramatically affect the unique interactions between animals and their environment.

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