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Why Does This Lizard Have Such Fabulous Colours?

The views expressed are those of the author and are not necessarily those of Scientific American.


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Male common wall lizards, Podarcis muralis

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.

The various colours these lizards can become as they change over time

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.

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.

Bite force is a good measure of how dominant a male is

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 Behaviour90, 73-81.

 

Felicity Muth About the Author: Felicity Muth is an early-career researcher with a PhD in animal cognition. Follow on Twitter @notbadscience.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. SJCrum 5:58 pm 04/28/2014

    For information, the reason lizards can change colors is simply because, I kid you not, God made them that way to protect them from predators. Zebras are striped, which is totally impossible by evolving, and to make them more difficult to see as well. And, there are many others obviously also.
    As for the color changes, what do you suppose is the science that causes them to change, and also what does the lizard do to cause it as well? Have you, (hee, hee), ever asked a lizard what gets its motor running to do something like that? Real toughie question, huh? (hee, hee, again)
    Well, I will answer that because it’s so fun.
    The science about how their bodies change colors is that the atoms in the skin make a chemical that matches the background they are in, and that chemical causes the atoms in the skin to change positions to where the electrons then radiate the correct color. As far as the atom positions, they have to be tilted to the side and to where the angle of the light coming from the electrons is perfect for the right color. Blue, for example, is a far-to-the-side angle, while yellow is straight out and no altered angle at all.
    As for how the correct color is determined by the lizard’s skin atoms, that is that the atoms can detect the light coming from the surrounding radiated light, as when those come from plants. As for how it detects that light, it needs only to absorb the radiated light and then send a nerve signal to the lizard’s brain. And the brain then sends a signal to the part of the brain that causes the atoms to tilt properly.
    So, as far as what causes the non-furry varmint to have this occur, it simply looks at the surrounding vegetation and then think “that looks really good to hide in.” And, wallah, the fairly itty, bitty brain does all of the rest of it.
    Cool, huh? And, (hee, hee), you thought I didn’t know and was fully full of patouie, huh? (hee, hee, again) Nope!

    Link to this

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