Transvestite Lizards Imitate Females
Juvenile Augrabies Lizards Hide From Bigger Males by Acting Female
Apr 27, 2009
Platysaurus broadleyi – Augrabies Flat Lizard – is a brilliantly coloured reptile living among the rocks along the Orange River in the Western Cape of South Africa. Adult males have bright blue head shading to blue-green necks, yellow chest and front legs, and orange brown rear quarters and tail, and stand out dramatically against the rocks. Females and young lizards are a quiet brownish grey.
As young males develop their distinctive sexual colouring they are liable to be attacked and injured or killed by larger adults wanting to keep the females for themselves. Smaller males, whose colour has not changed very much, are able to hide among groups of females. These mimics or ‘transvestites’ are termed ‘shemales’.
Associate Professor Martin Whiting of the University of the Witwatersrand, South Africa, has been studying P. broadleyi for 15 years, and his co-researcher, Associate Professor Scott Keogh at The Australian National University, for about eight years. Their paper on the protective mimicry of the juvenile males: ‘Flat lizard female mimics use sexual deception in visual but not chemical signals’, was co-authored with Dr Jonathan Webb of the University of Sydney, and is published online in Proceedings of the Royal Society: B.
Transvestite Lizards Move Safely with Females
Since female lizards are almost as big as adult males, the transvestite lizards, or shemales, can mingle safely with them and not be noticed by the brightly coloured males, Associate Professor Scott Keogh said.
A population of Augrabies Flat Lizards is usually evenly divided between males and females. Males defend their own small territories and the females roam the rocky territory. So the shemales can wander around the rocks at will, so long as their bright colouration hasn’t developed.
“By delaying the onset of colour to a more convenient period, these shemales are making the best of a bad situation,” he said. This offers them two advantages. “Not only can they avoid potentially dangerous bouts with dominant males, they can still have access to normally inaccessible females.”
Colours Only, not Pheromones in Augrabies’ Disguise
Although the juveniles’ lack of bright colouring helps them hide among the females, on closer encounter the adult males would recognise the transvestites as male by their pheromones.
Professors Keogh and Whiting and Dr Jonathan Webb experimented with about 100 specimens to test whether the juvenile lizards’ disguise was foolproof. They removed all pheromones and skin lipids that might signal gender from the transvestites, and then, by wiping pheromones onto their skin, relabelled some females and others male.
These individuals were then presented to adult males and their responses observed. Male lizards use their tongues to sample chemical scent and they responded by courting the she-males labelled as females, but not she-males labelled as males.
“Males are fooled by looks, but not by scent, ” said Dr Webb. “The shemales are able to maintain this deception by staying one step ahead of a prying male, and thereby avoiding a nosy tongue that might give the game away.”
Female Lizards Fooled but Don’t Object to Mimics
Because the immature males are about the same size and colouring as the females, and females are free to wander the rocky area at will, they assume the shemales they meet are females like themselves.
However, Professor Keogh said, the immature males took advantage of their ease of approach to the females that their disguise gave them, and actively courted the true females.
While they might initially be surprised at the approach, the females are usually not unwilling to mate with the juveniles.
See Also: Colourful Fish Mimics Identity Theft
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