Conspicuous Chameleons

14 March, 2008

Male chameleon display
Male chameleon display
Source: Adnan Moussalli

Chameleons are camouflage experts, but is that why they change colour?

New research by Museum Victoria’s Dr. Adnan Moussalli and Devi Stuart-Fox at the University of Melbourne shows that colour change evolved to enable chameleons to flash bright, attention-grabbing colours to other chameleons – quite the opposite of camouflage.

'Their ability to rapidly change colours – within seconds – enables them to use bright colours to attract a mate or intimidate a rival when they need to – but remain camouflaged at other times,' explained Adnan.

This finding, published in the prestigious journal PLoS Biology, turns the popular idea that colour change evolved to enable chameleons to match different backgrounds on its head.

Using a spectrometer, which measures the full range of colours from ultra-violet to infra-red, the researchers measured colour change in 21 species of dwarf chameleon in South Africa.

Unlike humans, chameleons can see in the ultraviolet so their display colours appear even more conspicuous to other chameleons.  Being slow-moving, they rely on their superb colour vision to communicate from afar.

The key finding was that species which can change colour the most are those with displays most noticeable to other chameleons. This suggests that the need to communicate using colour has driven the evolution of colour change.

'If colour change evolved to enable camouflage,' said Adnan, 'we would expect species with the greatest capacity for colour change to have the greatest range of background colours that they need to match in their environments – but we found no evidence for this.'

Devi and Adnan spent four years in South Africa researching the fascinating behaviour of dwarf chameleons before moving to Melbourne last year. 'Chameleons can be hard to find and tricky to study – which is perhaps why we know so little about them. We’re keen to continue our research – there’s so much more to discover.'

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Male to female chameleon display