This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Despite having the underwhelming name the ‘common wall lizard’, this lizard sports some amazing colours on its underside. Although its back is a boring brown colour, presumably to be less visible to predators, the males have some fabulous colours on their bellies, as well as UV-blue patches down their sides (sadly not visible to us). However, not all wall lizards have the same colour belly. Some are orange, some are white and some are yellow.
Researchers recently proposed that perhaps these colours had a function in social signalling. This way, the lizard could keep its ‘true colours’ hidden, away from the prying eyes of potential predators, and then flash them towards fellow wall-lizards at the appropriate moment. This would most likely be to show a fellow male lizard that you’re the most dominant lizard around.
To investigate this possibility, scientists looked at lizards in the south-eastern Pyrenees to see whether the more colourful lizards were more dominant. Dominance can be easily measured by how hard you can bite and how big and heavy you are.
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They found that particular features of the UV markings down the lizards sides were related to how dominant they were. However, the lizards’ colourful bellies did not seem to be related to any measures of dominance.
So, what’s going on with their colourful bellies if it’s not to do with dominance or fighting ability? The females in this species have the same colour polymorphisms as the males, except their colour is restricted to their throat instead of extending all the way down their belly. It seems that females choose males that are the same colour as themselves. What their babies look like isn’t yet known (or in other words, whether their colour is genetically determined). I look forward to the study that breeds colourful lizards to see how their offspring turn out.
Photo Credits
First figure: taken from Pérez et al. 2014
Second figure: taken from Pérez et al. 2013
Lizard biting: Laurent Lebois
References
Pérez i de Lanuza, G., Font, E., & Carazo, P. (2013). Colour assortative mating in a colour polymorphic lacertid lizard. Behavioral Ecology, 24, 273-279.
Pérez i de Lanuza, G., Carazo, P., & Font, E. (2014). Colours of quality: structural (but not pigment) coloration informs about male quality in a polychromatic lizard. Animal Behaviour, 90, 73-81.