The colors of the chameleon.

How to explain the variable coloration of chameleons? What path has evolution followed to get here? There are several hypotheses, and it is a good example of how the mechanisms of evolution work. In many places we can read that the extraordinary ability of the chameleon to change its coloration at will makes it a master of camouflage. And this may be true, indeed: a chameleon can hide really well in its environment. However it has been shown that camouflage is not the main use of this trait, but visual communication.

Devi Stuart-Fox and Adnan moussalli They have published a work after conducting a nice experiment with 21 species of chameleon. If color variability is an adaptation for camouflage, it is to be expected that species with the greatest capacity for color change will live in a habitat that is more variable or heterogeneous in color. On the other hand, if color variability is an adaptation for visual communication, it is to be expected that the species with the greatest capacity for color change will be the ones that make the most use of communication: attractive sexual display, more aggressive territorial protection , or in general greater intensity in communication between individuals. After studying the habitat of the species and the behavior of the specimens before different stimuli, it was concluded that there was no relationship between the heterogeneity of the habitat and the ability to change color, and there was a relationship between communication traits (non-chromatic) intense and ability to change color.

Nevertheless, Does this explain the origin of the trait? No. The trait may have arisen as an adaptation to camouflage, and later, after verifying that it was a usable tool in another field, being more strongly selected in species with communication more intense. It is the same that happens with the feathers of birds: they were born as a mechanism for maintaining temperature and they turned out to be a great tool for flying. This selection towards other uses may have distorted the original adaptation.

The colors of the chameleon

In reptiles, however, there is another hypothesis at the origin of the rare ability of the chameleon to change color: the thermoregulation. Being cold-blooded animals, coloration is important when it comes to absorbing more or less radiation and thus controlling their body temperature. Many animals have, for example, certain parts of their body darker than others, in order to “play” with position. Some species have dark sides and expand the ribs like small wings, to present a kind of wide and dark “solar plate” that absorbs a lot of radiation in a short time. The possibility of changing color, therefore, could also have been an adaptation to thermoregulation in some ancestor of chameleons.

Any of these three possibilities could have been originally given, regardless of what that ability is now used for. And it is that the mechanisms of evolution are not as simple as some think.

The colors of the chameleon